•A method of fermenting garlic using Lactobacillus plantarum Lp-115 as starter culture.•Fermentation decreases allicin and vinyl dithiins, but increased the concentration of diallyl polysulphides.•Blanching significantly decreases organosulphide content and H2S-releasing activity of blanched-fermented garlic.•Fermentation without blanching retains the H2S-releasing activity of garlic.Blanched and unblanched garlic were fermented using L. plantarum for investigation of organosulphide profiles, hydrogen sulphide-releasing activity, pH, titratable activity and microbial growth. Both raw and blanched garlic preparations allowed growth of L. plantarum with corresponding lowering of pH below 4.0 and an increase in titratable acidity from an initial value of less 0.05% to 0.3 and 0.5%, respectively. Fermentation, alone, decreased allicin and vinyl dithiins, but increased the concentration of DATS. The H2S-releasing activity, expressed as DATS-E (mmol DATS/g oil), of raw-fermented (2.91) garlic was not significantly different to that of raw (4.74) garlic, but values in blanched (0.41) and blanched-fermented (0.71) samples significantly decreased. Reductions in DATS-E values in blanched and blanched-fermented garlic corresponded well with the negative effect of blanching on the organosulphide concentrations of the products. Fermentation with L. plantarum retains H2S-releasing activity by increasing DATS, despite notable losses in allicin and allicin transformation products.

•Different cultivars of cranberries contain a wide range of organic acid contents.•Proanthocyanidins profiles were similar among the different cultivars investigated.•A-type (epi)catechin units were the main constituents of the proanthocyanidins.•Crowley and Howes showed promise as potential food resources for health use.Twenty-one cultivars of cranberry fruits (Vaccinium macrocarpon) grown in New Zealand were analysed for their physico-chemical characteristics including average fruit weight, total soluble solids content, pH, total titratable acidity, organic acids, and total anthocyanins. In addition, the total proanthocyanidin contents of the fruit were determined using 4-dimethylaminocinnamaldehyde assay, and the profiles were characterised using matrix-assisted laser desorption/ionization time of flight mass spectra. Between the different cultivars, there was a range of average fruit weight (0.75–1.84 g), total soluble solids content (9.7–12.8%), juice pH (2.61–2.86), total titratable acidity (3.74–8.77 g citric acid/L juice) and total anthocyanin content (1.63–2.87 mg cyanidin-3-glucoside/g dry weight). The 21 cranberry cultivars exhibited similar high performance liquid chromatography profiles for proanthocyanidins using a diol column. The cultivars of Crowley and Howes with the higher contents were found to contain mainly A type (epi)catechin extending units. Therefore, Crowley and Howes with high proanthocyanidin contents would be the best choice of the cultivars studied for the promotion of urinary tract health.

•S-allyl glutathione disulphide (GSSA) is a slow H2S donor.•GSSA showed anti-aging effects on S. cerevisiae at low concentrations.•3-Vinyl-3,4-dihydro-1,2-dithiin is a slow H2S donor.AbstractsThe slow hydrogen sulphide (H2S) releasing compound S-allyl glutathione disulfide (GSSA) from garlic, which can release H2S via α carbon substitution, showed anti-aging effects on the chronological lifespan (CLS) of yeast Saccharomyces cerevisiae. Hormesis was observed, showing lifespan extension at nanomolar concentrations (100–200 nM), whereas at high concentration (1 mM) toxicity were observed. A possible explanation therefore might be the beneficial properties of the recently discovered gasotransmitter hydrogen sulfide (H2S). Yet, 2-vinyl-4H-1,3-dithiin (2-VDT) and 3-vinyl-4H-1,2-dithiin (3-VDT) from garlic appeared both inactive in terms of prolonging the lifespan of yeast. While for 2-VDT these findings seem reasonable since it cannot release H2S, for 3-VDT the contrary was expected as H2S releasing properties were observed. The underlying mechanism of H2S release of 3-VDT was proposed to be a similar α carbon substitution-like observed for GSSA.

•Trithiolane reacts with glutathione slowly to release H2S.•Releasing of H2S by trithiolane is dependent on the cells.•Lead acetate paper test is an effective method for quantification of H2S donation activity.•Stinky bean is a good dietary source for H2S donors.Hydrogen sulphide (H2S) is a gasotransmitter with multiple cellular signaling functions, and substantial number of H2S donors has been reported for research and therapeutic applications. However, most of the H2S donors are synthetic compounds. Naturally occurring slow H2S releasing agents are rare, especially those found in fruits and vegetables. We report herein that 1,2,4-trithiolane (TTL), the major cyclic polysulphide from stinky bean, is a potent, slow releasing H2S donor. TTL is 6.35 times more effective than diallyl trisulphide (DATS) in terms of increasing the cellular H2S concentration in cultured cells. Moreover, TTL could release H2S in cultured cells for up to two days. HPLC and LC–MS study reveal that TTL releases H2S through a sluggish reaction with glutathione (GSH), during which the thiolate attacks the carbon to open the trithiolane ring, resulting in H2S and several glutathione-methylene-sulphide conjugates. The apparent rate constant was estimated to be (2.02 ± 0.38) × 10−5 s−1. Our results suggest that stinky bean, may be of potential as functional food with H2S donation property.

•Four types of noodles were incorporated with Malay cherry leaf aqueous extracts.•Digestibility of noodles was evaluated using in vitro study.•Noodles with 4% aqueous extracts showed significantly low rate of digestibility.•Physicochemical properties of noodles were not compromised by the extracts.Aqueous extracts of Malay cherry leaves was incorporated into wheat, rice, tapioca, and potato flours with the purpose to formulate noodles with slow digestibility. In vitro digestion studies of these noodle prototypes were carried out to evaluate their digestibility under simulated gastrointestinal conditions. Upon incorporation of 2–8% of aqueous extracts, all four different types of noodles exhibited dose dependency with varying degree of digestibility. The greatest reduction in digestibility was observed in 8% tapioca noodles (69.2%) after 180 min. While there was no significant change on the physicochemical properties of the noodles incorporated with different levels of aqueous extracts, the color of noodles was darker. Overall, the results showed that incorporating aqueous extracts is a promising way to mitigate the digestibility of starch in different starchy foods. This study showed a viable way to produce starchy foods with low glycemic index (GI) suitable for people with postprandial hyperglycemia.

•Leaves of Malay cherry contain proanthocyanidins with high degree of polymerization of 27.•Proanthocyanidins is composed of B-type polymer of (epi)catechins and (epi)gallocatechins.•It is a potent and mixed noncompetitive inhibitor against α-amylase.Type-II diabetes has become a health threat globally. One major challenge for diabetes patients is to control their post-prandial hyperglycaemia, which could be achieved through the inhibition of α-amylase and α-glucosidase. Lepisanthes alata (Malay cherry) was discovered as a promising edible plant with high starch hydrolase inhibition activities for corn starch hydrolysis with IC50 of its aqueous extracts at 0.77 ± 0.09 µg/mL (for porcine α-amylase) and 10.83 ± 0.67 µg/mL (for rat intestinal α-glucosidase). Proanthocyanidins were identified to be responsible as active compounds. The proanthocyanidin exhibited high degree (mDP at 27) of polymerization and was composed of (epi)catechins and (epi)gallocatechins linked through B-type 4–8 interflavanyl bonds. Inhibition kinetic study revealed that the proanthocyanidins were a mixed noncompetitive inhibitor against α-amylase but competitive inhibitor against α-glucosidase. Our discovery highlighted the potential of the leaves of L. alata for use in prevention of post prandial hyperglycaemia.

Diallyl trisulfide (DATS) reacts rapidly with glutathione (GSH) to release H2S through thiol–disulfide exchange followed by allyl perthiol reduction by GSH. Yet diallyl disulfide (DADS) only releases a minute amount of H2S via a sluggish reaction with GSH through an α-carbon nucleophilic substitution pathway. The results clarify the misunderstanding of DADS as a rapid H2S donor, which is attributed to its DATS impurity.

A novel nanohybrid ratiometric fluorescence probe for on-site and visual determination of nitrogen dioxide (NO2) has been designed. The hybrid probe comprises blue-colored fluorescence carbon nanodots (CDs) and red-colored emission CdTe quantum dots (QDs). Such hybridized probe exhibits dual emission bands centered at 460 and 665 nm, respectively. The blue fluorescence of CDs is insensitive to the analyte, whereas the red emission of QDs is specifically quenched by the analyte, resulting in a distinguishable color change from orange-red to blue upon exposure to NO2. The limit of detection for nitrogen dioxide is estimated to be 19 nM in aqueous solution. More importantly, the nanohybrid probe has been successfully applied in visual detection of gaseous NO2 with a detection limit of 1 ppm, suggesting its potential application for NO2 sensing.

A weakly fluorescent complex derived from a binaphthol–benzimidazole ligand was designed and synthesized for hydrogen sulfide at different pH conditions. It was demonstrated that the probe showed the same reactivity to various hydrogen sulfide species in a broad range of pH values to generate highly fluorescent product through a displacement reaction mechanism, whereas the product’s fluorescence spectrum exhibited a hypsochromic shift of ∼73 nm (2393 cm–1) as pH increased from neutral to basic, which can be used for distinguishing the various species of hydrogen sulfide. This turn-on fluorescence probe was highly selective and sensitive to hydrogen sulfide with a detection limit of 0.11 μM. It was then applied for evaluating the total content of sulfide (including hydrogen sulfide, hydrosulfide, and sulfide) as well as for the visual detection of gaseous H2S in air using a simple test paper strip.

•Garlic scape oil contains high amounts of polysulphides.•H2S releasing capacity of garlic scape oil is proportional to its polysulphide contents.•Acidic treatments of scape homogenates favours formation of polysulphides.•Stir-frying of garlic scapes eliminates the H2S releasing capacity of the oil.Hydrogen sulphide (H2S), viewed as a deadly environmental pollutant, is now intensively researched as the third gaseous signalling molecule, ubiquitously present and with a myriad of physiological functions. We studied garlic (Allium sativum L.) scapes, the underexplored yet widely consumed “flower stalks” of garlic, for their organosulphide constituents and H2S-releasing activity. Oils obtained from pH-adjusted (pH 3.0–9.0) puree contained 15 organosulphides that showed sensitivity to the pH values of the processing media. Disulphides are significantly higher in the oil obtained at basic pH while trisulphides and cyclic organosulphides were much higher in the oils isolated at the acidic to weakly acidic pH values. A cell-based fluorescent method was used to quantify the H2S-releasing capacity, expressed as diallyl trisulphide equivalents (DATS-E in mmol DATS/g). DATS-E values significantly increased with increasing concentrations of trisulphides and tetrasulphides but showed inverse relationship with the increase in disulphides concentration. Common cooking method of stir-frying resulted in loss of more than 96% of the organosulphides and the oil obtained had an 85-fold lower DATS-E value.

•A rapid assay for quantification of H2S releasing activity of organosulphides in cells.•The H2S releasing activity of essential oils of organosulphur rich foods is ranked.•Stinky beans contain high amount of natural H2S donors.Hydrogen sulphide (H2S) is a gaseous signalling molecule with multiple biological functions in the human body. Previous research demonstrates that diallyl trisulphide (DATS) and diallyl disulphide (the two major compounds of garlic oil) can be metabolized to generate H2S in biological conditions and modulate cell signalling. In this paper, a fluorescent method for quantification of H2S releasing capacity in cell lines was developed. MCF-7 cells in 96 well plate were incubated with a H2S probe BCu for 3 h, then treated with H2S donors for 2 h, which would be metabolized by the cells and produce H2S. The resulting H2S was captured by the probe and turn on its fluorescence, which was measured with a microplate reader. Linear dose response could be established between organosulphur concentration and fluorescence intensity, and the H2S releasing capacity of a sample was determined by comparing the slope of the regression curve with that of a DATS standard obtained in parallel. With this method, the H2S releasing capacity of ten organosulphur rich fruits and vegetables (garlic, red onion, yellow onion, scallion, shallot, leek, spring onion, Chinese chives, durian, and stinky beans) were evaluated and ranked. Stinky beans (a vegetable from Southeast Asia) topped the ranking with very high H2S releasing capacity, followed by garlic and yellow onion. Our work provides new thinking on the health benefits of organosulphur-rich foods.

•Organosulfides in garlic are strong hypochlorite scavengers.•Sulfur containing amino acids are stronger HClO scavengers than polysulfides.•Sulfur atoms of the sulfides are the acceptors of oxygen from hypochlorite.Dietary organosulfur compounds commonly found in garlic and cruciferous vegetables are potent hypochlorite scavengers as measured using a novel fluorescence assay based on quantum dots (QDs) as the nanoprobe. By using hydrogen sulfide as a standard, we quantified the HClO scavenging capacity of organosulfides in the following order: cysteine > methionine > phenethylisothiocyanate > diallyldisulfide ~ dially trisulfide. The reaction products of these sulfides with hypochlorite were characterized by LC–MS spectra, which revealed that the sulfur atoms are the acceptor of oxygen from hypochlorite. Finally, the hypochlorite scavenging activity of garlic upon heat treatment reduced the ClO− scavenging activity significantly.

A high throughput assay was applied to guide the isolation of a new pancreatic α-amylase inhibitor, dracoflavan B, from the dragon’s blood resin from Daemonorops draco. Applying C18 column, we successfully isolated both diastereomers and their structures verified by 1H NMR spectra in comparison with the literature values. Their activity in inhibition of pancreatic α-amylase with comparable IC50 values of 23 μM (A type) and 27 μM (B type) that are similar to that of acarbose. Dracoflavan B shows much weaker activity in inhibiting bacterial α-amylase and no activity towards fungal α-amylase. Moreover, both isomers show no inhibitory activity towards mammalian α-glucosidase. Kinetic analysis revealed that using starch as the substrate, dracoflavan B was a non-competitive α-amylase inhibitor with a Ki value of 11.7 μM. Lack of α-amylase inhibition for proanthocyanidin A2 dimer demonstrated that dracoflavan B hydrophobic nature of the B, A′, C′ and B′ rings are important for its α-amylase inhibition. In addition, selective chemical modification studies revealed that the phenolic group is also vital to dracoflavan B for its pancreatic α-amylase inhibition activity. Without the A ring phenolic hydrogen bond donor, the derivatives of dracoflavan B showed detrimental α-amylase inhibition. On the contrary, galloylation on the A ring phenolic OH group enhanced the activity as shown by the low IC50 (12 μM) against α-amylase which is 56% more potent as compared to dracoflavan B.

The development of convenient methods for sulfur dioxide and its derivatives analysis is critically important because SO2 causes worldwide serious environmental problems and human diseases. In this work, we show an unprecedented example of an energy-transfer-based fluorescence nanoprobe for selective and quantitative detection of SO2, through molecular engineering of the fluorescent carbon nanodots by a cyanine dye which have a unique reactivity to bisulfite, achieving a detection limit of 1.8 μM with a linear relationship (R2 = 0.9987). The specific detection was not interfered with other potential coexisted species. In addition, the probe is demonstrated for the determination of SO2 gas in aqueous solution as well as for visually monitoring of SO2 gas in air. This nanomaterial based probe is easily prepared, fast responding, and thus potentially attractive for extensive application for the determination of SO2 and other similar air pollutants.

Functional quantum dots (QDs) grafted with ferric dithiocarbamate complex layers (QDs-Fe(III)(DTC)3) were fabricated and demonstrated to be selectively reactive to nitric oxide. The dithiocarbamate (DTC) was covalently conjugated to the amine-coated QDs by a condensation reaction of the carboxyl in DTC and the amino polymer in surface of QDs. The weak fluorescence of QDs-Fe(III)(DTC)3 was attributed to the energy transfer between CdSe/ZnS and Fe(III)(DTC)3 complex at the surface of the functionalized quantum dots. Nitric oxide could greatly switch on the fluorescence of QDs-Fe(III)(DTC)3 by displacing the DTC in the Fe(III)(DTC)3 accompanied by reducing Fe(III) to Fe(II), thus shutting off the energy transfer way. The limit of detection for nitric oxide was estimated to be 3.3 μM and the specific detection was not interfered with other reactive oxygen species. Moreover, the probe was demonstrated for the sensing of gaseous nitric oxide, and the visual detection limit was as low as 10 ppm, showing the potential for sensing nitric oxide by the naked eye.

•Flavour active methionyl esters were prepared from butter oil.•Enzymatic method is superior to chemical method for synthesis of methionyl esters.•Odour activity of methionyl esters is correlated to fatty acid carbon chain length.Methionol-derived fatty acid esters were synthesised by both chemical and lipase catalysed esterification between fatty acids and methionol. Beneficial effects of both methods were compared qualitatively and quantitatively by GC–MS/GC-FID results. And the high acid and heat stability of our designed methionyl esters meet the requirement of the food industry. Most importantly, the sensory test showed that fatty acid carbon-chain length had an important effect on the flavour attributes of methionyl esters. Moreover, through Lipozyme TL IM-mediated transesterification, valuable methionol-derived esters were synthesised from the readily available natural material butter oil as the fatty acid source. The conversion of methionol and yield of each methionyl ester were also elucidated by GC–MS-FID.

•Enzymatic method is suitable for synthesising 2-phenethyl esters.•Fatty acid chain length determines the flavour attributes of 2-phenethyl esters.•Butter oil is a cost-effective material for 2-phenethyl ester flavourings.We report a simple enzymatic approach to synthesise phenethyl esters as natural flavouring materials. Chemical and lipase-catalysed esterification reactions between fatty acids of C4–C18 and 2-phenethyl alcohol were studied. Both methods were compared qualitatively and quantitatively by GC–MS/FID. The acid and thermal stabilities of 2-phenethyl esters were excellent and can meet the requirements of food matrices under most processing conditions. Sensory evaluation showed that each 2-phenethyl ester with a different carbon-chain-length fatty acid had unique sensory notes. Moreover, through Lipozyme TL IM-mediated transesterification, valuable 2-phenethyl alcohol-derived esters were synthesised from butter oil and 2-phenethyl alcohol. The influence of several physicochemical parameters (temperature, substrate molar ratio, enzyme loading, shaking speed and time) on the transesterification reaction was investigated to give optimal reaction conditions, leading to a high yield of 80.0%.

The glucose oxidase/peroxidase assay (GOP) is a coupled enzymatic assay commonly used in measuring glucose concentrations in biological sciences and food chemistry, particularly for quantification of α-glucosidase activity. However, we found that the GOP assay is prone to interference, especially from reducing substances such as polyphenolic compounds, which are commonly found in botanical materials. To establish the scope and limitation of the assay in measuring α-glucosidase inhibition activity, we systematically investigated the structural features of the polyphenolic compounds that can lead to false positives. Utilizing sodium dodecyl sulfate (SDS) as surrogate for the meriquinone intermediate formed during the reaction, we measured the reactivity of this redox active intermediate toward common flavonoids. Our results show that flavonoids with o-dihydroxy groups in the B-ring cause strong interference and that compounds with little DPPH scavenging activity do not have interference. Our results highlight the need for checking the suitability of the GOP assay first before it is applied in measuring α-glucosidase inhibition activity. In addition, when the literature data on α-glucosidase inhibition activity of botanical extracts or polyphenolic compounds using GOP assay are interpreted, potential false positives due to interference on the assay will need to be taken into consideration.

There is a growing account of the health benefits of H2S as an endogenous cell-signaling molecule. H2S from organic polysulfides, in particular, is increasingly gaining attention for their beneficial effects to cardiovascular health. Here, we studied shallot as a potential dietary source of organic polysulfides and examined the effects of processing conditions on its polysulfide profiles. Boiling, autoclaving, and freeze-drying were tested on whole and crushed shallot bulbs, analyzing their effect on the yield of organosulfides. Seventeen organosulfides, including disulfides, trisulfides, and cyclic polysulfides, were identified. Significant differences in the quantitative and qualitative profiles of organosulfides in the hydrodistilled and solvent extracted oils were observed. Freeze-drying retained the majority of the organosulfides, but the whole-autoclaved and whole-boiled shallots lost more than 95% of their organic polysulfides. Crushed-boiled and crushed-autoclaved shallot lost 76–80% of their organosulfides, likely due to the thermal sensitivity of these compounds. The organosulfide profiles are sensitive to the pH values of the processing media. In general, disulfides increased at basic pH (pH 9.0) while trisulfides and cyclic organosulfides are much higher at the acidic to neutral pH values (pH 3.0–5.0). Our results provide important information on the effects of processing conditions that are relevant for optimizing extraction of organosulfides from shallot for further studies evaluating their H2S-releasing activity.

Taking advantage of a nitrogen dioxide (NO2)-selective probe reported by our group previously, we have developed a fluorescent assay for quantifying NO2 absorbance capacity of flavanols and related polyphenolic compounds. A non-fluorescent NiII dithiocarbamate complex containing sulforhodamine fluorophore reacted rapidly and selectively with NO2 and turned on the fluorescence of the rhodamine. In the presence of radical scavengers, such as tea catechins, the rates of the fluorescence turning on by NO2 were suppressed in a dose-dependent manner. When a simple kinetic equation of the initial reaction rates is applied, the rate constants of the antioxidant reaction with NO2 can be derived using epicatechin as a reference standard, and the value is comparable to that obtained by the pulse radiolysis method. The scavenging capacity against NO2 of nine common phenolic compounds was evaluated, and their structure–activity relationship was also established. Additionally, the mechanism behind NO2 scavenging by phenolic compounds was determined by liquid chromatography–mass spectrometry and secondary mass, using epicatechin and gallic acid as examples. Our assay serves as the first example for convenient and sensitive quantification of NO2 scavenging activity of antioxidants.

Natural products with anti-aging property have drawn great attention recently but examples of such compounds are exceedingly scarce. By applying a high-throughput assay based on yeast chronological lifespan measurement, we screened the anti-aging activity of 144 botanical materials and found that dried roots of Salvia miltiorrhiza Bunge have significant anti-aging activity. Tanshinones isolated from the plant including cryptotanshione, tanshinone I, and tanshinone IIa, are the active components. Among them, cryptotanshinone can greatly extend the budding yeast Saccharomyces cerevisiae chronological lifespan (up to 2.5 times) in a dose- and the-time-of-addition-dependent manner at nanomolar concentrations without disruption of cell growth. We demonstrate that cryptotanshinone prolong chronological lifespan via a nutrient-dependent regime, especially essential amino acid sensing, and three conserved protein kinases Tor1, Sch9, and Gcn2 are required for cryptotanshinone-induced lifespan extension. In addition, cryptotanshinone significantly increases the lifespan of SOD2-deleted mutants. Altogether, those data suggest that cryptotanshinone might be involved in the regulation of, Tor1, Sch9, Gcn2, and Sod2, these highly conserved longevity proteins modulated by nutrients from yeast to humans.

We synthesized complexes of Ni(II) with dithiocarbamate ligands derived from the ortho and para isomers of sulforhodamine B fluorophores and demonstrated they are highly selective in reactions with nitrogen dioxide (NO2). Compared with the para isomer, the ortho isomer showed a much greater fluorescence increase upon reaction with NO2, which led to oxidation and decomplexation of the dithiocarbamate ligand from Ni(II). We applied this probe for visual detection of 1 ppm NO2 in the gas phase and fluorescence imaging of NO2 in macrophage cells treated with a nitrogen dioxide donor.

One new stilbene derivative (3,5,3′-trihydroxy-4′-methoxy-5′-isopentenylstilbene, MIP) and two new stilbene dimers (arahypin-11 and arahypin-12) together with three known stilbenoids (arachidin-1, arachidin-3, and SB-1) were isolated from black skin peanut seeds challenged by the fungal strain Rhizopus oligoporus. The structures of the three new compounds were elucidated by analysis of HRESIMS, UV, 1D and 2D NMR spectra. The antiadipogenic and cytotoxic effects of the isolated compounds were investigated using 3T3-L1 cells at a concentration range of 1–10 μM. Among the compounds tested, arachidin-1 inhibited the 3T3-L1 adipocyte differentiation dose-dependently, whereas arahypin-11 and arahypin-12 exhibited significant cytotoxicity in 3T3-L1 preadipocytes.

Two new stilbene dimers (arahypin-8 and arahypin-9) and one monomeric stilbene derivative arahypin-10 were isolated for the first time from wounded peanut seeds challenged by a Rhizopus oligoporus strain, a starter culture for soybean fermentation in Southeast Asia. The structures of the three new compounds were elucidated on the basis of HRESIMS, UV, 1D and 2D NMR spectroscopy and the plausible mechanism of their formation was proposed. In addition, these compounds showed insulin sensitizing effect by enhancing insulin-stimulated glucose uptake in differentiated 3T3-L1 adipocytes.Graphical abstractHighlights► Three new stilbenoids (arahypins) were isolated from fungal-stressed peanut seeds. ► Their structures were elucidated and formation mechanisms proposed. ► The three compounds showed insulin sensitizing activity in 3T3-L1 adipocytes.

Proanthocyanidins in unripe Manilkara zapota (chiku) were isolated using solvent extraction followed by Sephadex LH-20 fractionation with a yield of 0.9%. HPLC analysis using a diol column revealed well-resolved oligomers ranging from dimer to hexamer. The majority of the proanthocyanidins are composed of higher-degree oligomers appearing as one large peak in the chromatogram. Analysis of the proanthocyanidins using LC/MS showed that (epi)gallocatechins were the dominant extension unit in the proanthocyanidins. In agreement with this result, thiolysis treatment of the proanthocyanidins using mercaptoacetic acid produced thioether derivatives of (epi)gallocatechins as the major product and (epi)gallocatechin gallate derivatives as the minor product. The mean of the degree of polymerization was estimated to be 9.0. From MALDI-TOF MS, B-type gallocatechin oligomers up to decamer could be detected. The unripe chiku proanthocyanidins are thus good starting material for preparation of (epi)gallocatechin derivatives. The proanthocyanidins was shown to inhibit α-amylase with an IC50 value of 4.2 ± 0.2 μg/mL and inhibit α-glucosidase with an IC50 of 16.6 ± 0.3 μg/mL.

The effect of germination on bioactive components in legume seeds was investigated in terms of the antioxidant capacity and total phenolic contents. Germination increased the total phenolic content and antioxidant capacity of most seeds. Particularly in chickpea seeds, the isoflavone contents increased by over 100 fold, mainly due to the increase of formononetin and biochanin A level. As a result, these two compounds were conveniently isolated from the germinated seeds in preparative scale and structurally confirmed by UV–vis, ESI-MS, and 1H NMR spectroscopies. Isoflavonoid fingerprints analyzed by HPLC-PDA and LC-ESI-MS demonstrated that germination could significantly increase isoflavonoids diversity. Twenty-five isoflavonoids were detected and identified tentatively. These include 20 isoflavones, 2 isoflavanones, and 3 pterocarpan phytoalexins. Total isoflavonoid content of germinated chickpea was approximately 5-fold of that of germinated soybean. Our findings suggest that the germinated chickpea seeds could serve as a promising functional food rich in isoflavonoids.

Rapid oxidation of nonfluorescent pyrenyl-CH2SeAr (Ar = o-nitrophenyl) by hypochlorite yielded pyrenyl-CH2Cl and pyrenyl-CH2OH and turns on blue fluorescence, while slow oxidation of pyrenyl-CH2SeAr with excess H2O2 leads to pyrenyl-CHO which emits a bluish-green fluorescence. The homolog, pyrenyl-CH2CH2SeAr′ (Ar′ = o-nitrophenyl) reacts slower with H2O2 and ClO− giving the same product, vinyl pyrene.

The strongly near-IR-active mixed-valence diruthenium complex [Ru2TIEDCl4]Cl, where TIED = tetraiminoethylenedimacrocycle, was found to be a highly active catalyst for air oxidation of HS– forming polysulfide species and H2O2. The reaction provides a convenient method for the detection of the HS– generation rate of a H2S donor of medical importance.

Yellow camellia (section Nitidissima Chang) is a subgroup of tea plant with golden yellow flowers. It is a very rare species with potential as antioxidant rich plant as it is closely related to tea. We found, for the first time, that the antioxidant capacity and polyphenolic constituents of six yellow camellia species varied widely. Among them, the dry leaf of Camellia impressinervis had the highest level of oxygen radical absorbance capacity (ORAC, 2270.9 μmol TE/g), total phenolic content (TPC, 475.6 μmol GAE/g), and proanthocyanidin content (PAC, 66.1 μmol CE/g). The ORAC level correlated well with TPC (R2 = 0.9402), and PAC (R2 = 0.9954). The compounds responsible for antioxidant activities were further profiled by HPLC and LC–MS analysis. Compared to the commonly consumed tea leaves, yellow camellia leaves contain more diverse phenolic compounds, including ellagitannins, proanthocyanidins, taxifolin deoxyhexose, apigenin derivatives, kaempferol derivative, quercetin derivatives, glucosyl isorhamnetin, (epi)catechin-(epi)afezelechin polymers and platphyllosides. Unlike tea leaves, no caffeine is detected in the yellow camellia leaves. The antioxidant activity of the polyphenolic compounds were further verified by precolumn treatment of the extracts with a stable radical 2,2-diphenyl-1-picrylhydrazyl (DPPH).Highlights► Polyphenolic antioxidant profiles were characterised for an endangered plant, yellow camellia. ► Yellow camellia leaves contain platphyllosides and is rich in tannins, flavanols, and flavones. ► The polyphenolic antioxidants in yellow camellia are highly dependent on the nature of plants. ► In sharp contrast to common tea (with white flowers), there is no caffeine in yellow camellia.

A high-throughput method for rapid determination of starch hydrolase inhibition was developed using a 96-well microplate UV–vis reader to monitor the turbidity decrease over time. The area under the curve of turbidity measured over time was used to quantify the inhibitory effect of polyphenolic compounds on porcine pancreatic amylase, rat intestine α-glucosidase, and fungal amyloglucosidase. Acarbose equivalence (AE) was introduced for the first time and defined as IC50 of acarbose divided by the IC50 of the sample measured under the same 96-well plate. This way, the run-to-run variations are canceled out. Among the plant extracts tested, grape seed extracts (1,440 μmolAE/g) and cinnamon bark extracts (1600 μmolAE/g) are the most active in inhibiting rat intestine α-glucosidase. For porcine α-amylase inhibition, grape seed extracts (5710 μmol AE/g) are close to four times more active (equal weight basis) than acarbose (1550 μmolAE/g).

The effects of food grade fungus Rhizopus oligosporus stress on phytochemicals and phytoalexins of germinating peanut seeds were investigated by comparing the metabolic profiles of ungerminated (UG), germinated (G), and germinated seeds under fungal stress (GS). Three types of peanut seeds with different skin color (red, reddish brown, and black) were compared in the process. The polyphenolic contents were analyzed and correlated with antioxidant capacity for specific free radicals including peroxyl radical ROO• (ORAC), hydroxyl radical HO• (HORAC), superoxide radical O2•– (SORAC), and DPPH radical. The polyphenolic fingerprints analyzed by HPLC and LC-MSn showed that phenolic acids (coumaric, sinapinic, and ferulic acids derivatives) were the major group of phenolic compounds in ungerminated seeds. G or GS increased the level of phenolic acids, phytoalexins, and antioxidant capacity values in reddish and red peanuts but not in black peanuts. From the LC-MSn spectral data, 45 compounds were identified tentatively in the germinated peanuts, including 14 coumaric acids, 3 ferulic acids, 4 sinapinic acids, 2 hydroxybenzoic acids, 1 caffeic acid, 2 flavonoids, and 19 stilbenoids derivatives. Reddish brown germinated peanuts produced the highest amount of phytoalexins after GS with 55 compounds detected. Forty-five of these compounds were suggested as stilbenoid phytoalexins derivatives. The high content of phytoalexins may enhance the bioactivity of peanut seeds as functional food ingredients.

In the presence of the flavonols myricetin and quercetin, oxidation of hydroethidine (HE) by superoxide yielded ethidium (E+) instead of 2-hydroxyethidium (2-OH-E+). As a known pro-oxidant, myricetin alone was also found to be able to catalyze air oxidation of HE yielding exclusively E+. The reaction is inhibited by added superoxide dismutase, suggesting that superoxide is involved in the rate limiting step of the oxidation.In the presence of the flavonols myricetin and quercetin, oxidation of hydroethidine (HE) by superoxide yielded ethidium (E+) instead of 2-hydroxyethidium (2-OH-E+). As a known pro-oxidant, myricetin alone was also found to be able to catalyze oxidation of HE to E+. The superoxide formation rates were quantified from the oxidation kinetics.

A one-pot reaction between two molecules of 5-diethylamino-2-nitrosophenol with one molecule of 2-butynyl bromide gave rise to a new heterocyclic compound (structure shown above) consisting of one benzoxazole and one benzoxazine ring. The reaction works equally well with 1-phenyl-3-chloro-1-propyne. It was also found that 5-diethylamino-2-nitrosophenol reacts with R-CH2Br (R = aryl or vinyl) to give benzoxazoles with good functional group tolerance and high yield.

Four types of water-soluble quantum dots (QDs) grafted with different organic coating layers were fabricated, and their sensitivities for hypochlorite/hypochlorous acid (HClO) were examined. It was found that QDs with HClO reactive (methylamino and sulphide groups) coating layers exhibited a protective effect on HClO quenching of QD fluorescence, whereas QDs with hydrocarbon and carboxylate coating layers showed least protection to QD fluorescence quenching by HClO and, thus, has the highest sensitivity for the detection of HClO. The QDs with carboxylate coating layers (QDs-poly-CO2−) was successfully applied to the quantification of HClO in tap water. The excellent selectivity of the QDs-poly-CO2− toward hypochlorite against other reactive oxygen species allowed us to monitor myeloperoxidase activity. Finally, the QDs-poly-CO2− was also used for the detection of hypochlorite in HL60 cells by fluorescent imaging. Hence, QD-poly-CO2− exhibits great promise as a selective and sensitive HClO probe in chemical and biological systems.

Black soybeans were germinated with or without Rhizopus oligosporus for 3 days. The samples collected from each day were freeze-dried and extracted with chloroform−methanol−water mixture to simultaneously obtain organic phase (lipophilic extract) and aqueous phase (hydrophilic extract). In the lipophilic extract, α-, γ-, and δ-tocopherol were drastically decreased by 51%, 97%, and 88%, respectively, after 3 day germination under stress. On the other hand, the lipid peroxide concentration was increased in the fungi stressed, germinating beans from day 2 onward, while it was continually decreased in the nonstressed germinating counterpart. The change of antioxidant capacity (ORACoil value) was correlated to the changes of tocopherols and lipid peroxide concentrations. In nonstressed germinatng beans, ORACoil value dropped by 38% after 3 days, while in the fungi-stressed germinating beans, ORACoil was decreased by 80%. In hydrophilic extract, the antioxidant activity, measured by ORAChydro assay, is about 80 times higher than the ORACoil values, but there is no significant change before and after germination (either with or without stress). The total phenolic content in the hydrophilic extract increased only slightly by 9% in germinated beans and 15% in fungus-stress germinated samples, respectively. The advantage of stress germination of soybeans in enriching phytoalexins is traded off by loss of tocopherols.

Current work investigated the ability of different tea (green, oolong and black teas) in inhibiting human salivary α-amylase (HSA) and mammalian α-glucosidase (AGH). The inhibitory profiles were correlated to their major polyphenol content (theaflavins and catechins). The fully fermented black tea was demonstrated to be most potent in inhibiting HSA and AGH (IC50 of 0.42 to 0.67 and 0.56 to 0.58 mg of tea leaves/mL respectively). Its capability in retarding the digestion of a real food system (rice noodle) was further elucidated with an in vitro digestion study. Results indicated that black tea was able to retard starch digestion moderately, thereby allowing a gradual reduction of sugar liberation. Polyphenolic profile analysis suggested that the oxidized catechins, theaflavins, may be responsible for its activity. We have found that refractive index (RI) measurement is a rapid, direct, and highly convenient method for quantifying the degree of enzymatic starch digestion and kinetics. The RI method has good linearity range, limit of detection (0.1596 mg/mL, maltose equivalent) and limit of quantitation (0.6312 mg/mL) and was successfully applied in our study.

The photoluminescence of nonfluorescent molecularly engineered quantum dots (QDs) with iron(III) dithiocarbamates was selectively switched on by nitric oxide. Such functional QDs consisted of CdSe−ZnS nanocrystals as fluorophores and surface bound tris(N-(dithiocarboxy)sarcosine)iron(III) as reactive centers for nitric oxide. The fluorescence of the QDs was quenched by energy transfer between the excited QD cores and the surface bound iron(III) dithiocarbamates due to their optical energy overlapping. Nitric oxide restored the fluorescence of the QDs through reduction of the surface bound iron(III) complexes to iron(I)−NO adducts and thus shutting down the energy transfer pathway. The fluorescence of the iron(III) complex engineered QDs was selectively and quantitatively restored by nitric oxide but not by other reactive oxygen species. Such a property of the functional QDs could be used for sensing nitric oxide based on the fluorescence “turn on” mechanism.

Reaction of dried mangosteen pericarps powders with mercaptoacetic acid in the presence of hydrochloric acid in methanol afforded 4β-(carboxymethyl)sulphanyl-(−)-epicatechin methyl ester, 1, in 4.5% yield. The structure of 1 was characterised by 1H, 13C NMR, and mass spectra. Two protons on the prochiral methylene carbon next to sulphur atom give rise to characteristic AB pattern peaks indicating its association to chiral environment as is the case in 1. Compound 1 is a potential synthon towards other epicatechin derivatives due to its labile C–S bond under weakly basic conditions. Reaction 1 with epicatechin gave B2. If 3,5-dimethoxyaniline was used, 4β-(2′-amino-4′,6′-dimethoxyphenyl)epicatechin, 2, was isolated in moderate yield. Reaction of 1 with mercaptoethanol leads to synthesis of 4β-(2-hydroxyethylthio)epicatechin, 3, in good yield. Finally mercaptoacetic acid was used as an alternative for successful determination of mean degree of polymerisation of PAs isolated from pine bark, grape seeds, cocoa bean, and mangosteen.

This study investigated the antioxidant and antidiabetic effects of baicalin, as well as its effects in combination with the antidiabetic drug metformin. Three groups of streptozotocin-induced diabetic rats were given the following treatments for 30 days: (1) 500 mg/kg metformin; (2) 120 mg/kg baicalin; (3) 500 mg/kg metformin + 120 mg/kg baicalin. In addition, vehicle-treated diabetic and nondiabetic controls were used in the experiment. The rats treated with baicalin and metformin + baicalin had significantly elevated (p < 0.05) hepatic activities of superoxide dismutase, catalase, and glutathione peroxidase compared with the vehicle- and metformin-treated groups. Plasma and hepatic lipid peroxide concentrations of the baicalin- and baicalin + metformin-treated groups were significantly reduced (p < 0.05). In addition, baicalin significantly reduced plasma and hepatic triglycerides and cholesterol levels. The study thus showed that baicalin mitigated oxidative stress as well as enhanced the antidiabetic effect of metformin by improving the antioxidant status.

We report herein a characterization of an oil-in-water (o/w) microemulsion consisting of 12% methyl linoleate (or styrene in weight %), 29% surfactant Tween-20, 15% n-butanol, and 44% 75 mM potassium phosphate buffer (pH 7.04). The oil phase droplet size, determined by dynamic light scattering, is 19.3 nm with polydispersity at 0.103. When methyl linoleate is replaced with styrene, the droplet size increases to 63 nm but with much narrower polydispersity at 0.047. The droplet size of styrene is confirmed by polymerization of the styrene in the microemulsion. The polystyrene particles isolated have diameters of ∼70 nm determined by a scanning electronic microscope. Both microemulsions remain stable for two months as expected for a thermodynamically stable system. The methyl linoleate oxidation is induced by AAPH, and the effects of radical scavengers are evaluated in a high throughput fashion using an oxygen sensor coated 96-well microplate Oxygen Biosensor Systems. From the oxygen consumption kinetic curves, the antioxidant capacity can be calculated using Trolox as the standard. The synergistic effect of hydrophilic antioxidants and α-tocopherol was measured for representative flavonoids. Chlorogenic acid has the best synergistic effect of 44.8%. The assay, coined as ORACE standing for oxygen radical absorbance capacity in microemulsion, provides a model system in evaluating antioxidant capacity of phenolic compounds in a heterogeneous system relevant to food and cosmetic applications.

Black soybeans [Glycine max (L.) Merrill] were germinated under fungal stress with food grade R. oligosporus for 3 days and were homogenized and fermented with lactic acid bacteria (LAB) to produce soy yogurt. Fungal stress led to the generation of oxylipins [oxooctadecadienoic acids (KODES) isomers and their respective glyceryl esters] and glyceollins—a type of phytoalexins unique to soybeans. In soy yogurt, the concentrations of total KODES and total glyceollins were 0.678 mg/g (dry matter) and 0.953 mg/g, respectively. The concentrations of other isoflavones (mainly genistein and daidzein and their derivatives) in soy yogurt remained largely unchanged after the processes compared with the control soy yogurt. Germination of black soybean under fungal stress for 3 days was sufficient to reduce stachyose and raffinose (which cause flatulence) by 92 and 80%, respectively. With a pH value of 4.42, a lactic acid content of 0.262%, and a maximum viable cell count of 2.1 × 108 CFU/mL in the final soy yogurt, soy milk from germinated soybeans under fungal stress was concluded to be a suitable medium for yogurt-making. The resulting soy yogurt had significantly altered micronutrient profiles with significantly reduced oligosaccharides and enriched glyceollins.

Twenty-seven cultivars of mulberry fruits (Morus atropurpurea Roxb) were analyzed for their total phenolic content, total anthocyanin content, and peroxyl radical scavenging capacities. The proanthocyanidin contents of the fruit were also quantified using 4-dimethylamino-cinnamaldehyde assay, and characterization was attempted using electrospray ionization mass spectra. The phenolic compounds of mulberry fruits were characterized using HPLC with ESI-MS and diode array detection. Results showed that the content of mulberry fruits varied with different cultivars with total phenolic content, total anthocyanin content, total proanthocyanidin content, and peroxyl radical scavenging capacities ranging from 0.060−0.244, 0.001−0.056, 0.001−0.015, and 0.301−1.728, respectively. Good correlations were observed among the phenolic, anthocyanin, and proanthocyanidin contents and the radical scavenging capacities of mulberry fruits. Mulberry fruits were found to contain low amount of proanthocyanidins. The high total phenolic content of mulberry fruits were mainly contributed by anthocyanins, rutin, and chlorogenic acids. The lipid soluble antioxidants are profiled by an HPLC method developed in-house, and the results of selected mulberry fruits revealed significant amounts of lutein and δ- and γ-tocopherols but low α-tocopherol. Our results provide useful antioxidant nutritional information of a mulberry cultivar that has potential for large scale plantations.

Oligomeric proanthocyanidins were extracted from mangosteen pericarps and fractionated by a Sephadex LH-20 column to give 0.66% yield (dry matter). 13C and 1H NMR signals showed the presence of predominantly procyanidins together with a few prodelphinidin units along with small amounts of stereoisomers of afzelechin/epiafzelechin, catechin/epicatechin, and gallocatechin/epigallocatechin. Depolymerization with benzylmercaptan resulted in epicatechin thioether as the major product, and the mean degree of polymerization was determined to be 6.6. The electron spray ionization–mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectra revealed the dominant B type oligomers with mainly epicatechin units and with a small amount of A type oligomers. The isolated proanthocyanidins are potent peroxyl radical scavengers as evidenced by the high oxygen radical scavenging capacity at 1.7 × 104 µmol TE/g, much higher than that of pine bark and grape seed extracts.

α-Amylase inhibitor (α-AI) activity of Garcinia mangostana, commonly known as mangosteen, pericarp extracts was studied by assay guided fractionations from lipophilic to hydrophilic using combined solvent extraction and Amberlite XAD2 adsorption chromatography. Neither the lipophilic, xanthone containing fraction, nor the highly polar fraction, which has no affinity on Amberlite XAD2, showed any α-AI. The fraction that shows very high inhibitory activity contains primarily polyphenols and can be adsorbed on Amberlite XAD2. The IC50 of 5.4 µg/mL of this fraction is comparable to that of acarbose, a prescribed α-AI used in the control of type II diabetes, at 5.2 µg/mL. Total phenolic content (TPC) of each fraction was measured and the TPC has no correlation with the α-AI activity. The lipophilic fraction contains mainly xanthones as revealed by HPLC-MS analysis. Colorimetric analysis coupled with UV–vis and IR spectroscopic analysis demonstrated that the fractions with high α-AI activity are primarily oligomeric proanthocyanidins (OPCs) with little gallate moiety. There is also evidence to show that the α-AI by these OPCs is not purely by nonspecific protein complexation. Both tannic acid and G. mangostana OPCs precipitate BSA equally well but G. mangostana OPCs are 56 times more effective in inhibiting α-amylase.

Microbial-stressed germination of black soybeans leads to generation of a group of oxylipins, oxooctadecadienoic acids (KODEs, including 13-Z,E-KODE, 13-E,E-KODE, 9-E,Z-KODE, and 9-E,E-KODE), and their respective glyceryl esters in addition to glyceollins, a known phytoalexins present in wild and fungi-infected soybeans. Four fungi, Aspergillus niger, Aspergillus oryzae, Rhizopus oligosporus, and white rice yeast (Aspergillus niger wry), were applied to compare their efficiency on inducing these compounds during black soybean germination. Overall, R. oligosporus, the starter culture used in tempeh fermentation, gives the highest amounts of KODEs and glyceollins. The glyceollins and KODEs were isolated by preparative HPLC, and the structures were determined by 1H NMR, UV–Vis, and MS spectra. On the basis of the unequal distribution of the KODEs isomers, an enzymatic reaction, instead of a nonenzymatic free radical chain reaction, is responsible for their formations. Together with other oxylipins and glyceollins, the KODEs may contribute to the soybean's defensive response to fungal infection via reaction with protein thiol groups and cell membranes. The stress-germinated black soybeans may be used as ingredients for further processing of novel functional food products with unique nutritional and flavor profiles.

This article contains experimental data on the identification and quantification of the organosulfides on boiled garlic extracts. Data included are related to the research article “Boiling enriches the linear polysulfides and the hydrogen sulfide-releasing activity of garlic” (R. Tocmo, Y. Wu, D. Liang, V. Fogliano, D. Huang, 2016) [1]. Characterization was carried out by GC–MS and HPLC. Dose-response curves obtained from the cell-based H2S-releasing capacity assay of allicin transformation products, namely vinyl dithiins and ajoene are also included. DATS-E values were calculated from these dose-response curves to quantify the contribution of the individual polysulfides to the H2S-releasing capacity of boiled extracts.