Methylglyoxal (MGO), a reactive dicarbonyl species, is thought to contribute to the development of long-term pathological diabetes as a direct toxin or as an active precursor of advanced glycation end products (AGEs). Trapping MGO by dietary phenols to inhibit the MGO induced AGE formation is an approach for alleviating diabetic complications. The present study investigated whether dietary compounds with different structures and active sites have the additive capacity to trap MGO. Ginger phenolic constituent [6]-shogaol and tea flavonoid (−)-epicatechin were selected and tested under simulated physiological conditions, showing that they additively trapped about 41% MGO at a concentration of 10 μM within 24 h. Furthermore, whether [6]-shogaol and epicatechin can retain their MGO trapping efficacy in vivo or a biotransformation limits their MGO trapping capacity remain virtually unknown. An acute mouse study was carried out by giving a single dose of [6]-shogaol, epicatechin, and the combination of both ([6]-shogaol + epicatechin) through oral gavage. A mono-MGO adduct of [6]-shogaol was identified from [6]-shogaol and [6]-shogaol + epicatechin treated mice, and mono- and di-MGO adducts of epicatechin and its metabolite, 3′-O-methyl epicatichin, were detected in urine samples collected from epicatechin and [6]-shogaol + epicatechin treated mice. To our knowledge, this is the first study demonstrating the additive MGO trapping efficacy of [6]-shogaol and epicatechin and that [6]-shogaol and epicatechin retained their MGO trapping capacity in mice.Keywords: additive effect; epicatechin; methylglyoxal; trapping; [6]-shogaol;

Saponins are one type of widespread defense compound in the plant kingdom and have been exploited for the production of lead compounds with diverse pharmacological properties in drug discovery. Oats contain two unique steroidal saponins, avenacoside A, 1, and avenacoside B, 2. However, the chemical composition, the levels of these saponins in commercial oat products, and their health effects are still largely unknown. In this study, we directly purified 5 steroidal saponins (1–5) from a methanol extract of oat bran, characterized their structures by analyzing their MS and NMR spectra, and also tentatively identified 11 steroidal saponins (6–16) on the basis of their tandem mass spectra (MSn, n = 2–3). Among the five purified saponins, 5 is a new compound and 4 is purified from oats for the first time. Using HPLC-MS techniques, a complete profile of oat steroidal saponins was determined, and the contents of the two primary steroidal saponins, 1 and 2, were quantitated in 15 different commercial oat products. The total levels of these two saponins vary from 49.6 to 443.0 mg/kg, and oat bran or oatmeal has higher levels of these two saponins than cold oat cereal. Furthermore, our results on the inhibitory effects of 1 and 2 against the growth of human colon cancer cells HCT-116 and HT-29 showed that both had weak activity, with 2 being more active than 1.

Increasing evidence supports dicarbonyl stress such as methylglyoxal (MGO) as one of the major pathogenic links between hyperglycemia and diabetic complications. In vitro studies have shown that dietary flavonoids can inhibit the formation of advanced glycation end products (AGEs) by trapping MGO. However, whether flavonoids can trap MGO in vivo and whether biotransformation limits the trapping capacity of flavonoids remain virtually unknown. In this study, we investigated whether genistein (GEN), the major soy isoflavone, could trap MGO in mice by promoting the formation of MGO adducts of GEN and its metabolites. Two different mouse studies were conducted. In the acute study, a single dose of MGO and GEN were administered to mice via oral gavage. In the chronic study, MGO was given to mice in drinking water for 1 month and then GEN was given to mice for 4 consecutive days via oral gavage. Two mono-MGO adducts of GEN and six mono-MGO adducts of GEN phase I and microbial metabolites were identified in mouse urine samples from these studies using liquid chromatography/electrospray ionization tandem mass spectrometry. The structures of these MGO adducts were confirmed by analyzing their MSn (n = 1–4) spectra as well as by comparing them with the tandem mass spectra of authentic standards. All of the MGO adducts presented in their phase II conjugated forms in mouse urine samples in the acute and chronic studies. To our knowledge, this is the first in vivo evidence to demonstrate the trapping efficacy of GEN in mice and to show that the metabolites of GEN remain bioactive.

Regular aspirin use has been convincingly shown to reduce the risk of colorectal cancer. However, long-term use of aspirin leads to gastrotoxicity. Herein, we designed and synthesized a novel class of resveratrol-based aspirin prodrugs to simultaneously release aspirin and resveratrol to attenuate the side effects caused by aspirin. Prodrug RAH exerted enhanced anticancer activities which are better than a physical mixture of aspirin and resveratrol as well as each individually. Metabolism of RAH in mice showed that the majority of RAH is decomposed to release resveratrol and aspirin or salicylic acid either in the intestine or after absorption. Mechanistic studies demonstrate RAH inhibits cell cycle arrest through downregulation of cyclins and induces apoptosis by activation of caspase-3 in cancer cells. These findings highlighted the improved anticancer properties of resveratrol-based aspirin prodrugs. RAH may represent novel and safe alternatives of aspirin for the purpose of daily use in the future.

Growing evidence has shown that ascorbic acid (ASA) can contribute to protein glycation and the formation of advanced glycation end products (AGEs), especially in the lens. The mechanism by which ascorbic acid can cause protein glycation probably originates from its oxidized form, dehydroascorbic acid (DASA), which is a reactive dicarbonyl species. In the present study, we demonstrated for the first time that four tea flavanols, (−)-epigallocatechin 3-O-gallate (EGCG), (−)-epigallocatechin (EGC), (−)-epicatechin 3-O-gallate (ECG), and (−)-epicatechin (EC), could significantly trap DASA and consequently form 6C- or 8C-ascorbyl conjugates. Among these four flavanols, EGCG exerted the strongest trapping efficacy by capturing approximate 80% of DASA within 60 min. We successfully purified and identified seven 6C- or 8C-ascorbyl conjugates of flavanols from the chemical reaction between tea flavanols and DASA under slightly basic conditions. Of which, five ascorbyl conjugates, EGCGDASA-2, EGCDASA-2, ECGDASA-1, ECGDASA-2 and ECDASA-1, were recognized as novel compounds. The NMR data showed that positions 6 and 8 of the ring A of flavanols were the major active sites for trapping DASA. We further demonstrated that tea flavanols could effectively inhibit the formation of DASA-induced AGEs via trapping DASA in the bovine lens crystallin-DASA assay. In this assay, 8C-ascorbyl conjugates of flavanols were detected as the major adducts using LC-MS. This study suggests that daily consumption of beverages containing tea flavanols may prevent protein glycation in the lens induced by ascorbic acid and its oxidized products.

In this study, we investigated the preventive effects of carnosic acid (CA) as a major bioactive component in rosemary extract (RE) on high-fat-diet-induced obesity and metabolic syndrome in mice. The mice were given a low-fat diet, a high-fat diet or a high-fat diet supplemented with either 0.14% or 0.28% (w/w) CA-enriched RE (containing 80% CA, RE#1L and RE#1H), or 0.5% (w/w) RE (containing 45% CA, RE#2), for a period of 16 weeks. There was the same CA content in the RE#1H and RE#2 diets and half of this amount in the RE#1L diet. The dietary RE supplementation significantly reduced body weight gain, percent of fat, plasma ALT, AST, glucose, insulin levels, liver weight, liver triglyceride, and free fatty acid levels in comparison with the mice fed with a HF diet without RE treatment. RE administration also decreased the levels of plasma and liver malondialdehyde, advanced glycation end products (AGEs), and the liver expression of receptor for AGE (RAGE) in comparison with those for mice of the HF group. Histological analyses of liver samples showed decreased lipid accumulation in hepatocytes in mice administrated with RE in comparison with that of HF-diet-fed mice. Meanwhile, RE administration enhanced fecal lipid excretion to inhibit lipid absorption and increased the liver GSH/GSSG ratio to perform antioxidant activity compared with HF group. Our results demonstrate that rosemary is a promising dietary agent to reduce the risk of obesity and metabolic syndrome.

Considerable evidence suggests that long-term pathological diabetes is a result of the accumulation of tissue macromolecules that have been progressively modified by nonenzymatic glycation of protein. Methylglyoxal (MGO) is a highly reactive endogenous dicarbonyl metabolite derived from multiple sources such as glucose and lipids and is thought to contribute greatly to protein glycation and the formation of advanced glycation end products (AGEs). In this study, we demonstrated for the first time that both [6]-shogaol (6S) and [6]-gingerol (6G), the major active components in ginger, markedly trapped MGO in vitro and consequently formed mono-MGO adducts, 6S-MGO and 6G-MGO, which were purified from the respective chemical reaction and characterized as novel compounds by NMR experiments and LC–MS/MS approaches. We revealed that the α-carbon of the carbonyl group in the side chain of 6S or 6G is the major active site for trapping MGO. We also demonstrated that 6S and 6G could effectively inhibit the formation of MGO-induced AGEs via trapping MGO in a time-dependent manner in the human serum albumin (HSA)–MGO system. Mono-MGO adducts, 6S-MGO and 6G-MGO, were determined to be the major conjugates in 6S- and 6G-treated HSA–MGO assays, respectively, using LC–ESI-MS techniques. These findings showed the potential effects of 6S and 6G on the prevention of protein glycation, suggesting regular consumption of ginger root extract may attenuate the progression of MGO-associated diabetic complications in patients.

Consumption of whole grains has been reported to be associated with a lower risk of colorectal cancer. Recent studies illustrated that phytochemicals in wheat bran (WB) may protect against colorectal cancer. There is a growing interest in the phytosterol contents of foods as either intrinsic or added components due to their beneficial health effects. However, little is known whether phytosterols in WB contribute the observed chemopreventative activity of the grain. In the present study, we directly purified and identified four oxyphytosterols 1–4 from sterol-enriched fraction of WB, and also successfully synthesized five sterol oxides 5–8 and 13. Using these nine compounds as references, we outlined a comprehensive profile of steroids in WB using tandem liquid chromatography mass spectrometry with electrospray ionization (LC-ESI/MSn, n = 2–3) techniques for the first time. Among them, three sterol oxides 13, 14, and 18 are novel compounds, and 14 compounds 3, 4, 6–11, 13, 14, 16, and 18–20 were reported in WB for the first time. Our results on the inhibitory effects of available sterol oxides 1–8 and 13 against the growth of human colon cancer cells HCT-116 and HT-29 showed that compounds 2–8 exerted significant antiproliferative effects, with oxysterol 8 being the most active one in both cells. We further demonstrated that four most active sterol oxides 5–8 could induce cell death through the apoptosis pathway. Our results showed that phytosterols, particularly oxyphytosterols, in WB possess significant antiproliferative properties, and thereby may greatly contribute the observed chemoprevention of the whole grain wheat.

•Tea catechins are mainly metabolized into hydroxyphenyl-γ-valerolactone and small phenolic acids by microbiota in vitro and in vivo.•The major metabolic pathway of theaflavins is the cleavage of the galloyl group.•Strong inter-individual variations on the metabolism of tea polyphenols are found in both in vitro and in vivo models.•Microbial metabolites of tea polyphenols showed strong antioxidant, anti-proliferative, and anti-inflammatory activities.Tea is one of the most widely consumed beverages worldwide and has received increasing attention from researchers and food industries for various reasons mainly related to its health benefits. Polyphenols, such as catechins for green tea and theaflavins and thearubigins for black tea, are considered to be the main active components of tea. Recently, there is increasing awareness that the beneficial health effects of tea could be partly contributed by breakdown products of its polyphenols formed in the gut. Different studies have been carried out to understand the formation of microbially derived metabolites of tea components and their bioactivities. In general, tea catechins are typically transformed to specific hydroxyphenyl-γ-valerolactones, which could be further metabolized to smaller phenolic acids by gut flora. This review summarizes the current knowledge on the metabolism of major tea components by gut microbiota and the bioactivities of their metabolites.

Reactive dicarbonyl species, such as methylglyoxal (MGO), are considered as the major precursors of advanced glycation end products (AGEs), which are believed to be one of the physiological causes of diabetes and its complications. Scavenging of reactive dicarbonyl species using naturally occurring flavonoids has been proposed as an effective way to prevent diabetic complications. To elucidate the structural requirements of flavonoids in scavenging MGO, seven flavonoids (quercetin, luteolin, epicatechin, genistein, daidzein, apigenin, and phloretin) and five sub-components of the flavonoids (gallic acid, phloroglucinol, pyrogallol, pyrocatechol, and resorcinol) were examined in this study. Our results showed the following: (1) 1,2,3-trihydroxybenzene (pyrogallol) has higher MGO scavenging activity than 1,3,5-trihydroxybenzene and 1,2- and 1,3-dihydroxybenzene, and substitution at position 5 of pyrogallol diminished the scavenging activity, indicating that position 5 is the active site of pyrogallol; (2) the A ring is the active site of flavonoids in contributing the MGO-trapping efficacy, and the hydroxyl group at C-5 on the A ring enhances the trapping efficacy; (3) the double bond between C-2 and C-3 on the C ring could facilitate the trapping efficacy; and (4) the number of hydroxyl groups on the B ring does not significantly influence the trapping efficacy. In addition, we found there is an additive effect in MGO trapping by two common flavonoids, quercetin and phloretin, indicating that flavonoid-enriched foods and beverages hold great promise to prevent the development of diabetic complications.

Shogaols, the major constituents of thermally processed ginger, have been proven to be highly effective anticancer agents. Our group has identified cysteine-conjugated shogaols (M2, M2′, and M2″) as the major metabolites of [6]-, [8]-, and [10]-shogaol in human and found that M2 is a carrier of its parent molecule [6]-shogaol in cancer cells and in mice, while being less toxic to normal colon fibroblast cells. The objectives of this study are to determine whether M2′ and M2″ behave in a similar manner to M2, in both metabolism and efficacy as anticancer agents, and to further explore the biological pro-apoptotic mechanisms of the cysteine-conjugated shogaols against human colon cancer cells HCT-116 and HT-29. Our results show that [8]- and [10]-shogaol have similar metabolic profiles to [6]-shogaol and exhibit similar toxicity toward human colon cancer cells. M2′ and M2″ both show low toxicity against normal colon cells but retain potency against colon cancer cells, suggesting that they have similar activity to M2. We further demonstrate that the cysteine-conjugated shogaols can cause cancer cell death through the activation of the mitochondrial apoptotic pathway. Our results show that oxidative stress activates a p53 pathway that ultimately leads to p53 up-regulated modulator of apoptosis (PUMA) induction and down-regulation of B-cell lymphoma 2 (Bcl-2), followed by cytochrome c release, perturbation of inhibitory interactions of X-linked inhibitor of apoptosis protein (XIAP) with caspases, and finally caspase 9 and 3 activation and cleavage. A brief screen of the markers attenuated by the proapoptotic activity of M2 revealed similar results for [8]- and [10]-shogaol and their respective cysteine-conjugated metabolites M2′ and M2″. This study highlights the cysteine-conjugated metabolites of shogaols as novel dietary colon cancer preventive agents.

In this study, we identified Nrf2 as a molecular target of [6]-shogaol (6S), a bioactive compound isolated from ginger, in colon epithelial cells in vitro and in vivo. Following 6S treatment of HCT-116 cells, the intracellular GSH/GSSG ratio was initially diminished but was then elevated above the basal level. Intracellular reactive oxygen species (ROS) correlated inversely with the GSH/GSSG ratio. Further analysis using gene microarray showed that 6S upregulated the expression of Nrf2 target genes (AKR1B10, FTL, GGTLA4, and HMOX1) in HCT-116 cells. Western blotting confirmed upregulation, phosphorylation, and nuclear translocation of Nrf2 protein followed by Keap1 decrease and upregulation of Nrf2 target genes (AKR1B10, FTL, GGTLA4, HMOX1, and MT1) and glutathione synthesis genes (GCLC and GCLM). Pretreatment of cells with a specific inhibitor of p38 (SB202190), PI3K (LY294002), or MEK1 (PD098059) attenuated these effects of 6S. Using ultra-high-performance liquid chromatography–tandem mass spectrometry, we found that 6S modified multiple cysteine residues of Keap1 protein. In vivo 6S treatment induced Nrf2 nuclear translocation and significantly upregulated the expression of MT1, HMOX1, and GCLC in the colon of wild-type mice but not Nrf2–/– mice. Similar to 6S, a cysteine-conjugated metabolite of 6S (M2), which was previously found to be a carrier of 6S in vitro and in vivo, also activated Nrf2. Our data demonstrated that 6S and its cysteine-conjugated metabolite M2 activate Nrf2 in colon epithelial cells in vitro and in vivo through Keap1-dependent and -independent mechanisms.

Dietary chemoprevention of cancer offers the possibility to suppress or inhibit cancer growth before it develops into more advanced and lethal stages. To this end, identification of novel compounds and their mechanisms of action is constantly needed. In this study, we describe that a major component of dry ginger (Zingiber officinalis), [6]-shogaol (6S), can be quickly metabolized in A549 human lung cancer cell line. One of the resulting metabolites, the cysteine-conjugated 6S (M2), exhibits toxicity to cancer cells similar to the parent compound 6S, but is relatively less toxic toward normal cells than 6S. We further demonstrate that both compounds can cause cancer cell death by activating the mitochondrial apoptotic pathway. Our results show that the cancer cell toxicity is initiated by early modulation of glutathione (GSH) intracellular content. The subsequently generated oxidative stress activates a p53 pathway that ultimately leads to the release of mitochondria-associated apoptotic molecules such as cytochrome C, and cleaved caspases 3 and 9. In a xenograft nude mouse model, a dose of 30 mg/kg of 6S or M2 was able to significantly decrease tumor burden, without any associated toxicity to the animals. This effect was correlated with an induction of apoptosis and reduction of cell proliferation in the tumor tissues. Taken together, our results show that 6S metabolism is an integral part of its anticancer activities in vitro and in vivo. This allows us to characterize M2 as a novel compound with superior in vivo chemopreventive properties that targets similar anticancer mechanisms as 6S.

Shogaols, a series of major constituents in dried ginger (Zingiber officinale), show high anticancer potencies. Previously, we reported that a major metabolite resulting from the mercapturic acid pathway, 5-cysteinyl-[6]-shogaol (M2), showed comparable growth inhibitory effects toward cancer cells to [6]-shogaol (6S). Here, we probe the mechanism by which M2 exerts its bioactivity. We utilized a series of chemical stability tests in conjunction with bioassays to show that thiol-conjugates display chemopreventative potency by acting as carriers of active ginger component 6S. M2 chemical degradation to 6S was observed in an environment most resembling physiological conditions, with a pH of 7.4 at 37 °C. The metabolic profiles of M2 in cancer cells HCT-116 and H-1299 resembled those of 6S, indicating that its biotransformation route was initiated by deconjugation. Further, the presence of excess glutathione significantly delayed 6S and M2 metabolism and counteracted cell death induced by 6S and M2, suggesting that increasing available free thiols exogenously both promoted the formation of 5-glutathionyl-[6]-shogaol (M13) and inhibited the production of free 6S from M2 deconjugation, resulting in delayed 6S cell entry and bioactivity. Given the chemopreventative properties of M2 and our observations in vitro, we investigated its metabolism in mice. M2 and 6S showed similar metabolic profiles in mouse urine and fecal samples. Six new thiol-conjugated metabolites (M16–M21), together with previously reported ones, were identified by LC/MS. In particular, the increase of 5-N-acetylcystenyl-[6]-shogaol (M5) and its 3′-demethylated product (M16) abundance in mouse feces after treatment with M2 indicates that in addition to acting as a carrier of 6S, M2 is also directly acetylated to M5, which is further demethylated to M16 in vivo. In conclusion, the cysteine-conjugated metabolite of [6]-shogaol M2 exerts its bioactivity by acting as a carrier of 6S in both cancer cells and in mice.

Sphingolipids are known to have diverse properties and physiological functions. These distinctive lipids have been identified in wheat bran, a food well-known for its chemopreventive activity. However, the complete profile of sphingolipids in wheat bran and their contributions to the cancer preventive effect of wheat bran have not been fully explored until this study. Twelve sphingolipids (1–12) were purified from wheat bran extract and characterized by analyzing their 1D and 2D NMR spectra, and seven sphingolipids (13–19) were characterized based on their tandem mass spectra (MSn: n = 2–4). To the best of our knowledge, this is the first report of sphingolipids 1, 6–9, 11–14, and 16–19 in wheat bran. In particular, 2-N-(2′-hydroxy-15′-tricosenoyl)-4-hydroxysphinganine (peak 17) is a novel compound. Additionally, compounds 2–4 were reported with complete NMR data for the first time. Sphingolipids (1–12) showed little growth inhibition against human colon cancer cell lines (HCT-116 and HT-29) in vitro.

Gingerols are a series of major constituents in fresh ginger with the most abundant being [6]-, [8]-, and [10]-gingerols (6G, 8G, and 10G). We previously found that ginger extract and its purified components, especially 10G, potentially stimulate both the primitive and definitive waves of hematopoiesis (blood cell formation) in zebrafish embryos. However, it is still unclear if the metabolites of 10G retain the efficacy of the parent compound toward pathological anemia treatment. In the present study, we first investigated the metabolism of 10G in zebrafish embryos and then explored the biotransformation of 10G in humans. Our results show that 10G was extensively metabolized in both zebrafish embryos and humans, in which two major metabolites, (3S,5S)-[10]-gingerdiol and (3R,5S)-[10]-gingerdiol, were identified by analysis of the MSn spectra and comparison to authentic standards that we synthesized. After 24 h of treatment of zebrafish embryos, 10G was mostly converted to its metabolites. Our results clearly indicate that the reductive pathway is a major metabolic route for 10G in both zebrafish embryos and humans. Furthermore, we investigated the hematopoietic effect of 10G and its two metabolites, which show similar hematopoietic effects as 10G in zebrafish embryos.

6-Gingerol, a major pungent component of ginger (Zingiber officinale Roscoe, Zingiberaceae), has been reported to have antitumor activities. However, the metabolic fate of 6-gingerol and the contribution of its metabolites to the observed activities are still unclear. In the present study, we investigated the biotransformation of 6-gingerol in different cancer cells and in mice, purified and identified the major metabolites from human lung cancer cells, and determined the effects of the major metabolites on the proliferation of human cancer cells. Our results show that 6-gingerol is extensively metabolized in H-1299 human lung cancer cells, CL-13 mouse lung cancer cells, HCT-116 and HT-29 human colon cancer cells, and in mice. The two major metabolites in H-1299 cells were purified and identified as (3R,5S)-6-gingerdiol (M1) and (3S,5S)-6-gingerdiol (M2) based on the analysis of their 1D and 2D NMR data. Both metabolites induced cytotoxicity in cancer cells after 24 h, with M1 having a comparable effect to 6-gingerol in H-1299 cells.

Black tea contains two major pigments, theaflavins and thearubigins. These polyphenols have been associated with certain health benefits including prevention of heart disease and cancer. Elucidating and characterizing the structural aspects of thearubigins, the most abundant pigment in black tea, has been a challenge for many years. Therefore further studies of black tea polyphenols must be conducted in effort to solve this thearubigin dispute. In the present study, black tea extract was found to possess theaflavin trigallate and tetragallate by means of liquid chromatography/electrospray ionization mass spectrometry. These structures were confirmed by analysis of the MSn (n = 1–4) spectra and comparison of the MS/MS spectra of the product ions to the MS/MS spectra of authentic (−)-epigallocatechin-3-gallate, (−)-epicatechin-3-gallate and theaflavin-3,3′-digallate. To our knowledge, this is the first report to confirm the presence of theaflavin trigallate and tetragallate in black tea.

We have identified alkylresorcinols (ARs) as the major active components in wheat bran against human colon cancer cell growth (HCT-116 and HT-29) using a bioassay-guided approach. To further study the structure–activity relationships, 15 ARs and their intermediates (1–15) were synthesized expediently by the modified Wittig reaction in aqueous media, and six 5-alkylpyrogallols and their analogues (16–21) were prepared by the general Grignard reaction. The synthetic AR analogues were evaluated for activities against the growth of human colon cancer cells HCT-116 and HT-29 and the chymotrypsin-like activity of the human 20S proteasome. Our results found that (1) AR C13:0 and C15:0 (13 and 14) had the greatest inhibitory effects in human colon cancer cells HCT-116 and HT-29, while decreasing or increasing the side chain lengths diminished the activities; (2) two free meta-hydroxyl groups at C-1 and C-3 on the aromatic ring of the AR analogues greatly contributed to their antitumor activity; (3) the introduction of a third hydroxyl group at C-2 (20 and 21) into the aromatic ring of the AR analogues yielded no significant enhancement in activity against HCT-116 cells and decimated the effects against HT-29 cells, but dramatically increased the activity against the chymotrypsin-like activity of the human 20S proteasome; and (4) AR C11:0 (12) was found to have the greatest effect in a series of AR C9:0-C17:0 against the chymotrypsin-like activity of the human 20S proteasome.

Ginger is frequently consumed as a spice and has numerous medicinal properties. Extensive research has characterized the anti-inflammatory, antioxidant, and antitumor activities of ginger. Previously, we reported the mercapturic acid pathway as a major metabolic route of [6]-shogaol in mice and the thiol conjugates of [6]-shogaol existed in the glucuronidated and sulfated forms in mouse urine. However, their structures are still unknown. In the present study, we further investigated the phase II metabolism of thiol-conjugated [6]-shogaol in mouse urine, in which we identified sixteen phase II metabolites of thiol-conjugated [6]-shogaol: 5-cysteinyl-[6]-shogaol glucuronide (9), 5-N-acetylcysteinyl-[6]-shogaol glucuronide (10), 5-cysteinylglycinyl-[6]-shogaol glucuronide (11), 5-methylthio-[6]-shogaol glucuronide (12), 5-cysteinyl-M6 glucuronide (13 and 14), 5-cysteinyl-M6 sulfate (15 and 16), 5-N-acetylcysteinyl-M6 glucuronide (17 and 18), 5-cysteinylglycinyl-M6 glucuronide (19 and 20), 5-cysteinylglycinyl-M6 sulfate (21 and 22), and 5-methylthio-M6 glucuronide (23 and 24) using liquid chromatography/electrospray ionization tandem mass spectrometry. The structures of these metabolites were confirmed by analyzing their MSn (n = 1–4) spectra as well as comparing with the tandem mass spectra of authentic standards. To the best of our knowledge, this is the first report involving identification of phase II urinary metabolites of [6]-shogaol in mice.Highlights► Mouse urinary metabolic profile of thiol-conjugated [6]-shogaol was established. ► Sixteen phase II metabolites of thiol-conjugated [6]-shogaol were identified. ► Thiol conjugated [6]-shogaol are the substrates for glucuronidation and sulfation.

Black tea consumption has been associated with many health benefits including the prevention of cancer and heart disease. Theaflavins are the major bioactive polyphenols present in black tea. Unfortunately, limited information is available on their biotransformation. In the present study, we investigated the metabolic fate of theaflavin 3,3′-digallate (TFDG), one of the most abundant and bioactive theaflavins, in mouse fecal samples using liquid chromatography/electrospray ionization tandem mass spectrometry by analyzing the MSn (n = 1–3) spectra. Four metabolites theaflavin, theaflavin 3-gallate, theaflavin 3′-gallate, and gallic acid were identified as the major mouse fecal metabolites of TFDG. Glucuronidated and sulfated, instead of methylated metabolites of theaflavin 3-gallate, theaflavin 3′-gallate, and TFDG were detected and identified as the minor mouse fecal metabolites of TFDG. Our results indicate that TFDG can be degraded in mice. Further studies on the formation of those metabolites in TFDG-treated mice in germ-free conditions are warranted. To our knowledge, this is the first report on the biotransformation of TFDG in mice.

We and others have found that wheat bran oil is the active constituent in wheat bran for colon cancer prevention. However, the active components in wheat bran oil are still unknown. Using human colon cancer cells (HCT-116 and HT-29) as the guiding assays, we further purified the active components from wheat bran using column chromatography. In this study, we identified that a fraction containing 5-n-alk(en)ylresorcinols had the strongest inhibitory effect on the proliferation of human HCT-116 and HT-29 colon cancer cells. Further purification led to the identification of 14 5-alk(en)ylresorcinols. Among them, 7, (10′Z,13′Z,16′Z)-5-(nonadeca-10′,13′,16′-trienyl)resorcinol, is a novel compound and 5, 6, 9, 10, and 13 were purified as individual compounds for the first time. The identification and structural elucidation of these compounds were based on 1D and 2D NMR and tandem mass spectral analyses. All these compounds (1–14) except 10 were evaluated for growth inhibition of human colon cancer cell lines (HCT-116 and HT-29). Our results indicate that increasing the length of the side chain will diminish the inhibitory activity, and the existence of a double bond and a carbonyl group will strengthen such an activity.

Methylglyoxal (MGO) is a highly reactive endogenous metabolite derived from several nonenzymatic and enzymatic reactions, and identified as a well-known precursor of advanced glycation end products (AGEs). In the present study, genistein, a naturally occurring isoflavone derived from soy products, demonstrated significant trapping effects of MGO and consequently formed mono- and di-MGO adducts under physiological conditions (pH 7.4, 37 °C). More than 80.0% of MGO was trapped within 4 h, and the trapping efficiency could be up to 97.7% at 24 h. The reaction adducts formed from genistein and MGO under different ratios were analyzed using LC/MS. We also successfully purified and identified the major mono- and di-MGO conjugated adducts of genistein. The NMR data showed that positions 6 and 8 of the A ring of genistein were the major active sites for trapping MGO. We further demonstrated that genistein could effectively inhibit the formation of AGEs in the human serum albumin (HSA)-MGO assay. Two mono-MGO adducts and one di-MGO adduct of genistein were detected in this assay using LC/MS. The di-MGO adduct of genistein became the dominant reaction product during prolonged incubation. Results from this study, as well as our previous findings on (−)-epigallocatechin 3-gallate (EGCG), phloridzin and phloretin, indicate that dietary flavonoids that have the same A ring structure as genistein, EGCG, phloridzin, and phloretin may have the potential to inhibit the formation of AGEs by trapping reactive dicarbonyl species.

For the first time, a sensitive reversed-phase HPLC electrochemical array method has been developed for the quantitative analysis of 8 major ginger components ([6]-, [8]-, and [10]-gingerol, [6]-, [8]-, and [10]-shogaol, [6]-paradol, and [1]-dehydrogingerdione) in 11 ginger-containing commercial products. This method was valid with unrivaled sensitivity as low as 7.3−20.2 pg of limit of detection and a range of 14.5−40.4 pg for the limit of quantification. The levels of 8 ginger components in 11 different commercial products were quantified by use of this method. The results found that both levels and ratios among the 8 compounds vary greatly in commercial products.

Methylglyoxal (MGO), the reactive dicarbonyl intermediate generated during the nonenzymatic glycation between reducing sugars and amino groups of proteins, lipids, and DNA, is the precursor of advanced glycation end products (AGEs). Many studies have shown that AGEs play a major pathogenic role in diabetes and its complications. This study found that 2,3,5,4′-tetrahydroxystilbene 2-O-β-d-glucoside (THSG), the major bioactive compound from Polygonum multiflorum Thunb., can efficiently inhibit the formation of AGEs in a dose-dependent manner by trapping reactive MGO under physiological conditions (pH 7.4, 37 °C). More than 60% MGO was trapped by THSG within 24 h, which was much more effective than resveratrol and its methylated derivative, pterostilbene, the two major bioactive dietary stilbenes. The major mono- and di-MGO adducts of THSG were successfully purified and found to be mixtures of tautomers. LC-MS and NMR data showed that positions 4 and 6 of the A ring were the major active sites for trapping MGO. It was also found that THSG could significantly inhibit the formation of AGEs in the human serum albumin (HSA)−MGO assay and both mono- and di-MGO adducts of THSG were detected in this assay using LC-MS. The results suggest that the ability of THSG to trap reactive dicarbonyl species makes it a potential natural inhibitor of AGEs.