α-Glucosidase and lipase inhibitors play important roles in the treatment of hyperglycaemia and dyslipidemia. To identify novel naturally occurring inhibitors, a bioactivity-guided phytochemical research was performed on the pu-erh tea. One new flavanol, named (–)-epicatechin-3-O-(Z)-coumarate (1), and 16 known analogs (217) were isolated from the aqueous extract of the pu-erh tea. Their structures were determined by spectroscopic and chemical methods. Furthermore, the water extract of pu-erh tea and its fractions exhibited inhibitory activities against α-glucosidases and lipases in vitro; compound 15 showed moderate inhibitory effect against sucrase with an IC50 value of 32.5 μmol/L and significant inhibitory effect against maltase with an IC50 value of 1.3 μmol/L. Compounds 8, 10, 11 and 15 displayed moderate activity against a lipase with IC50 values of 16.0, 13.6, 19.8, and 13.3 μmol/L, respectively.One new flavanol, named (–)-epicatechin-3-O-(Z)-coumarate (1), and 16 known analogs (217) were isolated from the aqueous extract of the pu-erh tea. Compound 15 showed moderate inhibitory effect on sucrase with an IC50 value of 32.5 μmol/L and significant inhibitory effect on maltase in vitro with an IC50 value of 1.3 μmol/L; compounds 8, 10, 11 and 15 displayed moderate activity against a lipase with IC50 values of 16.0, 13.6, 19.8, and 13.3 μmol/L, respectively.Download high-res image (147KB)Download full-size image

•Six previously unknown diterpenoids were isolated from the root extracts of Salvia grandifolia.•The structures and configurations of the six compounds were elucidated.•Two of the isolated compounds showed vasorelaxant bioactivity.•Absolute configurations of castanolide and epi-castanolide were obtained.•Proposed biosynthetic pathways are provided.A phytochemical investigation of root extracts of Salvia grandifolia led to isolation of six previously unreported diterpenoids, grandifolias A–F, along with eight known compounds. The structures of grandifolias A–F were primarily established by extensive 1D and 2D NMR spectroscopic analyses, as well as HRESIMS data. Their absolute configurations were assigned by their calculated and experimental electronic circular dichroism spectra or by X-ray diffraction analysis. All of the diterpenoids were evaluated for their vasorelaxant effects. Grandifolia B and isograndifoliol both exhibited dose-dependent vasorelaxant effects on rat aortic rings, preconstricted by KCl or norepinephrine, with EC50 values of 36.36–74.51 μg/mL.Graphical abstractA phytochemical investigation of root extracts of Salvia grandifolia led to the isolation of six (1–6) previously unreported diterpenoids, whose structures and vasorelaxant effects were established.

Seven new triterpenes, inonotusol A–G (1–7), one new diterpene, inonotusic acid (8), and 22 known compounds were isolated from Inonotus obliquus. Their structures were elucidated on the basis of spectroscopic analysis, including homonuclear and heteronuclear correlation NMR (1H–1H COSY, ROESY, HSQC, and HMBC) experiments. In in vitro assays, compounds 6 and 8–16 showed hepatoprotective effects against d-galactosamine-induced WB-F344 cell damage, with inhibitory effects from 34.4% to 81.2%. Compounds 7, 17, and 18 exhibited selective cytotoxicities against KB, Bel-7402, or A-549 cell lines. Compounds 16 and 17 showed inhibitory effects against protein tyrosine kinases, with IC50 values of 24.6 and 7.7 μM, respectively.

•Six new pyrrolidine-type iminosugars along with four known ones were isolated from the leaves of Suregada glomerulata.•The new compounds 4–6 and 8 were characterized as rarely seen 4-deoxy pyrrolidine-type iminosugars.•The discovery of new compounds 9 and 10 with a C8 side chain expands the distribution of pyrrolidine-type iminosugars with a long-side chain in plants.•The 8-hydroxyoctyl side-chain represents a new addition for the molecular diversity of iminosugars.Phytochemical investigation of the H2O extract of leaves of Suregada glomerulata led to the isolation of ten pyrrolidine-type iminosugars. The chemical structures of the six new compounds (4–6, 8–10) were elucidated as 2,5-imino-2,4,5-trideoxy-d-manno-heptitol (4-deoxy-homoDMDP) (4), 2,5-imino-2,4,5-trideoxy-d-gulo-heptitol (5), 2,5-imino-2,4,5,6-tetradeoxy-d-gulo-heptitol (6), 6-C-butyl-4-deoxy-DMDP (8), 6-C-(8-hydroxyoctyl)-DMDP (9), and 6-C-(8-hydroxyoctyl)-2,5-dideoxy-2,5-imino-d-galactitol (10), respectively, on the basis of spectroscopic data analysis (NMR and HRESIMS). Compounds 4–6 and 8 were characterized as rarely seen 4-deoxy pyrrolidine-type iminosugars. Pyrrolidine-type iminosugars with a long-side chain have been found in the restrictive plant families Moraceae, Campanulaceae, and Hyacinthaceae. The discovery of compounds 9 and 10 with a C8 side chain from S. glomerulata (Euphorbiaceae) expands the range of distribution for the iminosugars in plants. The 8-hydroxyoctyl side-chain represents a new addition for the molecular diversity of iminosugars. The compounds 1–10 were evaluated for inhibitory activity against rat intestinal α-glucosidase. However, all the test compounds showed no significant inhibitory activities to the glucosidase.

Chemical investigation of the seeds of Prunus davidiana afforded seven new aromatic glucosides, i.e., the prupersins A–E (1–5) and compounds 6 and 7, as well as 11 known compounds. The structures of 1–7 were elucidated by spectroscopic data analysis and chemical evidence, and configurations were determined by hydrolysis experiments (1, 2, and 5) or electronic circular dichroism (6). Compounds 1–6 exhibited antioxidant activity aganist Fe2+-cysteine-induced rat liver microsomal lipid peroxidation, with malondialdehyde inhibitory rates of 50–67% and 53–57% at concentrations of 10–5 and 10–6 mol/L, respectively.

A water extract of the leaves of Suregada glomerulata (Euphorbiaceae) was found to inhibit rat small intestinal α-glucosidase. An examination of the extract afforded 20 iminosugars including one pyrrolidine and 19 piperidines. The structures of the 10 new compounds (11–20) were determined by NMR, and MS spectroscopic data analyses, and chemical correlations. The novelty of the identified compounds mainly stems from the loss of a hydroxy at C-4 and the presence of an 8-hydroxyoctyl side chain. Nine N-alkyl derivatives including N-methyl (1a, 8a, and 13a), N-butyl (1b, 2b, and 9b) and N,N-dimethyl (1c, 2c, and 9c) were synthesized. The compounds were tested for rat small intestinal α-glucosidase inhibitory activity. In total, 15 compounds, including compounds 11, 12, 15, and 19 and the three derivatives 8a, 9b, and 13a, showed inhibitory activity with IC50 values less than 40 μM. In vivo results showed that total alkaloids of S. glomerulata (10 mg/kg) and four major iminosugars 1, 2, 3, and 9 (10 mg/kg) can lower the postprandial blood glucose level after sucrose and starch load in healthy male ICR mice.

Two new eudesmane-type sesquiterpene lactones, 1-one-4-epi-alantolactone (1) and 4α,13-dihydroxy-5,7(11)-eudesmadien-12,8-olide (2), were isolated from the roots of Inula racemosa, together with six known compounds (3–8). The cytotoxic activities against five human cancer cell lines had been tested and compounds 3, 6, 7 and 8 exhibited moderate cytotoxic activities. Compounds 4 and 8 showed potent in vitro activities against the release of β-glucuronidase in rat polymorphonuclear leukocytes (PMNs) induced by platelet-activating factor (PAF), with the inhibitory ratios 65.4% (P < 0.01) and 80.5% (P < 0.001), at concentration of 10 μM, respectively.Graphical abstractTwo new eudesmane-type sesquiterpene lactones, 1-one-4-epi-alantolactone (1) and 4α,13-dihydroxy-5,7(11)-eudesmadien-12,8-olide (2), were isolated from the roots of Inula racemosa, together with six known compounds (3–8). The cytotoxic activities against five human cancer cell lines had been tested and compounds 3, 6, 7 and 8 exhibited moderate cytotoxic activities. Compounds 4 and 8 showed potent in vitro activities against the release of β-glucuronidase in rat polymorphonuclear leukocytes (PMNs) induced by platelet-activating factor (PAF), with the inhibitory ratios 65.4% (P < 0.01) and 80.5% (P < 0.001), at concentration of 10 μM, respectively.Highlights► There are two new eudesmanolides from this plant. ► We evaluated cytotoxic activities of compounds 1–8 against five human cancer cell lines, and compounds 3, 6, 7 and 8 exhibited moderate cytotoxic activities. ► The anti-PAF activities were also tested, and compounds 4 and 8 showed activities with the inhibitory ratios 65.4% (P < 0.01) and 80.5% (P < 0.001), at concentration of 10 μM, respectively.

Two new diterpenoids, 3,4,18β-cyclopropa-ent-abieta-8(14),13(15)-dien-16,12-olide (1) and 3-oxojolkinolide B (2), were isolated from the roots of Suregada glomerulata (Blume) Baill. Their structures were determined by spectroscopic evidences. Compound 2 showed moderate cytotoxicity.

From the aqueous extract of Acacia catechu, two new phenolic compounds (3R,4R)-3-(3,4-dihydroxyphenyl)-4-hydroxycyclohexanone (1) and (4R)-5-(1-(3,4-dihydrophenyl)-3-oxobutyl)-dihydrofuran-2(3H)-one (2) were obtained. Their structures were determined on the basis of spectroscopic analysis. Free-radical scavenging activities of them were evaluated.

A new alkaloid, sinensine (1), had been isolated from the fruiting bodies of Ganoderma sinense Zhao, Xu et Zhang. Its structure was elucidated on the basis of 1D and 2D spectral analysis. This alkaloid exhibited activity in protecting the injury induced by hydrogen peroxide oxidation on HUVEC, with EC50 value 6.2 μmol/L.

To find aldose reductase inhibitors, two previously unreported compounds, grandifolias H and I, and five known compounds, including rosmarinic acid and rosmarinic acid derivatives, were isolated from the roots of Salvia grandifolia. A series of rosmarinic acid derivatives was obtained from rosmarinic acid using simple synthetic methods. The aldose reductase inhibitory activity of the isolated and synthesized compounds was assessed. Seven of the tested compounds showed moderate aldose reductase inhibition (IC50 = 0.06–0.30 μM). The structure-activity relationship of aldose reductase inhibitory activity of rosmarinic acid derivatives was discussed for the first time. This study provided useful information that will facilitate the development of aldose reductase inhibitors.Download high-res image (165KB)Download full-size image