Triterpenoids and α-glucosidase inhibitory constituents from Salacia hainanensis

Thirteen triterpenoids (1–13), including two new lupane triterpenoids, salacinins A and B (1 and 2), as well as one new friedelane triterpenoid, salacinin C (3), were isolated from the roots and stems of Salacia hainanensis. The structures of new compounds were elucidated by extensive spectroscopic analysis including 1D and 2D NMR, and MS experiments. Compound 1 possesses rare 2,3-seco-lupane skeleton. Compounds 4, 6 and 7 showed inhibitory effects on α-glucosidase in vitro.     

Anti-inflammatory activity of sulfate-containing phenolic compounds isolated from the leaves of Myrica rubra

Three sulfated phenolic compounds, juglanin B (11R)-O-sulfate (1), myricetin 3´-O-sulfate (2), and ampelopsin 3´-O-sulfate (3), were isolated from the leaves of Myrica rubra. Compound 1 was a new sulfated lignan, 2 was a new sulfated flavone, and 3 was a known sulfated flavone. The structures of the new compounds (1 and 2) were determined by acid hydrolysis and spectroscopic methods, including IR, FAB-MS, 1D and 2D NMR. The inhibitory activities of compounds 1–3 and their hydrolysates (1a–3a) against LPS-induced cytokine (TNF-α, IL-1β, and IL-6) production in macrophage RAW 264.7 cells were evaluated. The 2 new compounds (1 and 2) and their aglycones (1a and 2a) significantly reduced LPS-induced expression of iNOS and COX-2 proteins.     

Characterization of tyrosinase inhibitors in the twigs of Cudrania tricuspidata and their structure–activity relationship study

The twigs of Cudrania tricuspidata were found to show strong tyrosinase inhibitory activity, and further detailed component analysis resulted in the isolation of a new flavanol glucoside, (2S,3S)-2,3-trans-dihydromorin-7-O-β-d-glucoside (1), plus twenty-seven known compounds (2–28). Their structures were elucidated on the basis of ESI-MS and NMR spectral data. Among the isolated compounds, trans-dihydromorin (8), oxyresveratrol (9), and steppogenin (12) were found to exhibit significant tyrosinase inhibition activities. Moreover, the structure–activity relationship of these isolated compounds was also discussed.     

Five new triterpenoidal saponins from the roots of Ilex cornuta and their protective effects against H2O2-induced cardiomyocytes injury

Five new ursane-type triterpenoidal saponins (1–5), together with five known ones (6–10), were isolated from the EtOH extract of the roots of Ilex cornuta. The structures of saponins 1–5 were elucidated as 19α-hydroxyurs-12-en-28-oic acid 3β-O-β-D-glucuronopyranoside (1), 19α-hydroxyurs-12-en-28-oic acid 3β-O-β-D-glucuronopyranoside-6-O-ethyl ester (2), 19α-hydroxyurs-12-en-28-oic acid 3β-O-α-L-arabinopyranosyl-(1 → 2)-β-D-glucuronopyranoside (3), 3β-O-[α-L-arabinopyranosyl-(1 → 2)-β-D-glucuronopyranosyl]-19α-hydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranosyl ester (4) and 3β-O-[α-L-arabinopyranosyl-(1 → 2)-β-D-glucuronopyranoside-6-O-methyl ester]-19α-hydroxyurs-12-en-28-oic acid 28-O-β-D-glucopyranosyl ester (5), on the basis of spectroscopic analyses (IR, ESI-MS, HR-ESI-MS, 1D and 2D NMR) and chemical reactions. Protective effects of compounds 1–10 against H₂O₂-induced H9c2 cardiomyocyte injury were tested. Compounds 1–5, 7, and 10 showed cell-protective effects. Among them compound 5 exhibited the highest activity. No significant DPPH radical scavenging activity was observed for compounds 1–10.     

Noreudesmane sesquiterpenoids from the leaves of Nicotiana tabacum

Six new 14-noreudesmane sesquiterpenoids, nicotabacosides A–F (1–6), along with five known sesquiterpenoids (7–11), were isolated from the leaves of Nicotiana tabacum. The structures of compounds 1–6 were elucidated as isorishitin 3-O-β-d-glucopyranoside (1), rishitin 3-O-β-d-glucopyranoside (2), rishitin 2-O-β-d-glucopyranoside (3), 1, 6-dehydro-rishitin 3-O-β-d-glucopyranoside (4), 2-hydroxyl-ligudentatol 3-O-β-d-glucopyranoside (5) and oxyglutinosone 3-O-β-d-glucopyranoside (6) based on extensive spectroscopic analyses (HRESIMS, UV, IR, 1D and 2D NMR). Their absolute configurations were determined by X-ray single-crystal diffraction and comparison of their electronic circular dichroism (ECD) spectra.     

Acyl quinic acid derivatives from the stems of Erycibe obtusifolia

Eleven new acyl quinic acid derivatives, 4-O-caffeoyl-3-O-syringoylquinic acid methyl ester (1), 4-O-caffeoyl-3-O-vanilloylquinic acid (2), 4-O-caffeoyl-3-O-vanilloylquinic acid methyl ester (3), 5-O-caffeoyl-3-O-vanilloylquinic acid (4), 5-O-caffeoyl-3-O-vanilloylquinic acid methyl ester (5), 5-O-caffeoyl-3-O-sinapoylquinic acid (6), 5-O-caffeoyl-4-O-vanilloylquinic acid (7), 4-O-(7‴S, 8‴R)-glycosmisoyl-5-O-caffeoylquinic acid methyl ester (8), 4-O-(7‴S, 8‴R)-glycosmisoyl-5-O-caffeoylquinic acid (9), 3-O-(7‴S, 8‴R)-glycosmisoyl-4-O-caffeoylquinic acid (10), and 3-O-(7‴S, 8‴R)-glycosmisoyl-4-O-caffeoylquinic acid methyl ester (11), have been isolated from the stems of Erycibe obtusifolia together with eight known compounds (12–19). Their structures were elucidated on the basis of spectroscopic data analysis (UV, IR, HRESIMS, CD, and 1D and 2D NMR) and chemical evidence. In in vitro assay, compounds 7 and 16–18 exhibited significant neuroprotective effects against rotenone induced PC12 cell damage at 10 μM.     

Sibiricasaponins A–E,five new triterpenoid saponins from the aerial parts of Polygala sibirica L.

Five new triterpenoid saponins, named as sibiricasaponins A–E (1–5), were isolated and identified from the aerial parts of Polygala sibirica L., together with nine known triterpenoid saponins (6–14). The chemical structures of the five new triterpenoid saponins (1–5) were elucidated as 3β,19α-dihydroxyurso-12-ene-23,28-dioic acid 3-O-β-d-glucuronopyranoside (1), pomolic acid 3-O-(3-O-sulfo)-α-l-arabinopyranoside (2), pomolic acid 3-O-(4-O-sulfo)-β-d-xylopyranoside (3), pomolic acid 3-O-(2-O-acetyl-3-O-sulfo)-α-l-arabinopyranoside (4), and 3-O-β-d-glucopyranosyl medicagenic acid 28-O-β-d-galactopyranosyl (1 → 4)-β-d-xylopyranosyl (1 → 4)-α-l-rhamnopyranosyl (1 → 2)-(4-O-acetyl)-[β-d-apiofuranosyl (1 → 3)]-β-d-fucopyranosyl ester (5), respectively, on the basis of spectroscopic data and physicochemical evidences. These isolated compounds (1–14) were evaluated for their anti-ischemic effects on oxygen/glucose deprivation (OGD) model in vitro, and only compound 7 showed a weak anti-ischemia effect, with EC₅₀ value of 46.7 μM.     

Antifungal compounds from turmeric and nutmeg with activity against plant pathogens

The antifungal activity of twenty-two common spices was evaluated against plant pathogens using direct-bioautography coupled Colletotrichum bioassays. Turmeric, nutmeg, ginger, clove, oregano, cinnamon, anise, fennel, basil, black cumin, and black pepper showed antifungal activity against the plant pathogens Colletotrichum acutatum, Colletotrichum fragariae, and Colletotrichum gloeosporioides. Among the active extracts, turmeric and nutmeg were the most active and were chosen for further investigation. The bioassay-guided fractionation led to the isolation of three compounds from turmeric (1–3) and three compounds from nutmeg (4–6). Their chemical structures were elucidated by spectroscopic analysis including HR-MS, 1D, and 2D NMR as curcumin (1), demethoxycurcumin (2) and bisdemethoxy-curcumin (3), erythro-(7R,8R)-Δ^8′-4,7-dihydroxy-3,3′,5′-trimethoxy-8-O-4′-neolignan (4), erythro-(7R,8R)-Δ8′-7-acetoxy-3,4,3′,5′-tetra-methoxy-8-O-4′-neolignan (5), and 5-hydroxy-eugenol (6). The isolated compounds were subsequently evaluated using a 96-well microbioassay against plant pathogens. At 30 μM, compounds 2 and 3 possessed the most antifungal activity against Phomopsis obscurans and Phomopsis viticola, respectively.     

Phenylethanoid glycosides from the stems of Callicarpa peii (hemostatic drug)

Two new trisaccharide intermediates of phenylethanoid glycosides, peiioside A₁/A₂ (1a/1b) and peiioside B (2), were isolated from the n-BuOH fraction of MeOH extract of the stems of Callicarpa peii H.T. Chang, together with five biogenetic relevant known compounds 3–7. The structures of compounds 1 and 2 were elucidated by extensive spectroscopic methods (especially 2D-NMR techniques) and acid-catalyzed hydrolysis as O-α-l-rhamnopyranosyl-(1″ → 3′)-O-[β-d-apiofuranosyl-(1‴ → 6′)] -4′-O-[(E)-caffeoyl]-d-glucopyranoside] (1a/1b), 3,4-dihydroxy-β-phenylethoxy-O-[β-d-apiofuranosyl-(1‴ → 6′)-α-l-rhamnopyranosyl-(1″ → 3′)-O-β-d-glucopyranoside] (2), respectively. On the basis of the isolated compounds, a presumable biogenetic pathway of the biologically interesting phenylethanoid glycosides about forsythoside B (3) and acteoside (4) isolated from this species was proposed. Isolation of five related intermediates (1–2, 5–7) provided further support for the biogenetic path. This is the first report about phytochemical research on C. peii and the biogenetic hypothesis of forsythoside B and acteoside.     

Three new phenolic compounds from the leaves of Rosa sericea

Two new flavonoids, quercetin-3-O-β-d-xylopyranosyl-(1 → 2)-α-d-ribopyranoside (1) and kaempferol-3-O-β-d-xylopyranosyl-(1 → 2)-α-d-ribopyranoside (2), and one new phenolic derivative, gallicin-p-O-(6′-O-caffeoyl)-β-d-glucoside (3), together with twelve known compounds were isolated from the leaves of Rosa sericea (Rosaceae family). The structures of the new compounds were established by means of spectroscopic analysis including one- and two-dimensional NMR spectroscopy. Some of the isolated compounds were tested for the cytotoxicity of a breast cancer cell (MCF-7) line. The results showed that rubanthrone A (4) has moderate cytotoxicity against the MCF-7 cell line.     

Three pairs of variecolortide enantiomers from Eurotium sp. with caspase-3 inhibitory activity

7-O-methylvariecolortide A (1), variecolortide B (2), and variecolortide C (3), the rare variecolortides existing in racemic manner, were isolated from an endolichenic fungal strain Eurotium sp. (No. 17-11-8-1). With the chiral HPLC technology, (−)-(S)-7-O-methylvariecolortide A (1a), (+)-(R)-7-O-methylvariecolortide A (1b), (−)-(S)-variecolortide B (2a), (+)-(R)-variecolortide B (2b), (−)-(S)-variecolortide C (3a), and (+)-(R)-variecolortide C (3b) were successfully separated and obtained. Their absolute configurations were firstly assigned by ECD experiment and ECD calculation. According to the relation of isolated compounds, a plausible biosynthetic pathway for variecolortides was proposed. In caspase-3 enzymatic assay, compounds 1–3 showed inhibitory activity, with IC₅₀ values of 1.7, 0.8 and 15.7 μM, respectively.     

New coumarin glycosides from the leaves of Diospyros crassiflora (Hiern)

Two new 5-methylcoumarin glycosides named diosfeboside A (1) and B (2) and five known compounds namely kaempferol 3-O-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranoside (3), ursolic acid (4), betulinic acid (5), stigmasterol (6) and stigmasterol 3-O-β-d-glucopyranoside (7) were isolated from the leaves of Diospyros crassiflora (Hiern). Their structures were established through interpretation of 1 and 2D NMR, mass spectra analysis and comparison with reported data. In vitro cytotoxic activity of the new compounds against human carcinoma cell lines (HL-60, Bel-7402, BGC-823, and KB) was evaluated and no cytotoxicity was observed for each of them.     

Cytotoxic cucurbitane triterpenoids isolated from the rhizomes of Hemsleya amabilis

Two new cucurbitane triterpenoids, 7β-hydroxycucurbitacin F-25-O-acetate (1) and 2β,3β,20(S),26,27-pentahydroxy-16α,23(S)-epoxycucurbita-5,24-dien-11-one (2) along with eleven known cucurbitane triterpenoids (3–13, resp.) were isolated from the rhizomes of Hemsleya amabilis Diels. The chemical structures of the new isolated compounds were elucidated unambiguously by spectroscopic data analysis. The cytotoxic activities of the isolated cucurbitane triterpenoids were evaluated against the HeLa human cancer cell lines. Hemslecin A (5), the main ingredient of H. amabilis, exhibited the significant cytotoxicity with IC₅₀ value of 0.389 μM.     

Iridoid and bis-iridoid glucosides from the fruit of Gardenia jasminoides

Three new iridoid glucosides, 6″-O-trans-feruloylgenipin gentiobioside (1), 2′-O-trans-caffeoylgardoside (2), jasmigeniposide A (3), and one new bis-iridoid glucoside, jasmigeniposide B (4), along with six known analogues (5–10), were isolated from the fruit of Gardenia jasminoides. Their structures were established on the basis of spectroscopic analyses and chemical methods. Anti-virus activity of isolated compounds were evaluated in vitro and only compound 9 showed moderate inhibitory activity against H1N1 with 50% effective concentration (EC₅₀) value of 104.36 μM, and selective index (SI) value greater than 4.79.     

2-Methyl-l-erythritol glycosides from Gardenia jasminoides

Two new glycosides, 2-methyl-l-erythritol-4-O-(6-O-trans-sinapoyl)-β-d-glucopyranoside (1) and 2-methyl-l-erythritol-1-O-(6-O-trans-sinapoyl)-β-d-glucopyranoside (2), along with two known triterpenoids (3–4), four quinic acid derivatives (5–8) and one flavonoid (9) were isolated from the fruit of Gardenia jasminoides. Their structures were elucidated through MS and 2D NMR experiments (HMQC and HMBC). Inhibitory effects of the isolated compounds on nitric oxide production in lipopolysaccharide-activated macrophages were evaluated. Though 2-methyl-d-erythritol and its glycosides have been reported in a few references, this is the first report about 2-methyl-l-erythritol glycosides. Based on this finding, we propose that 2-methyl-l-erythritol might be a new intermediate in the non-mevalonate biosynthesis of terpenoids.     

Polyacetylenes and anti-hepatitis B virus active constituents from Artemisia capillaris

Three new polyacetylenes, 8-(Z)-decene-4, 6-diyne-1, 3, 10-triol (1), 1, 3S, 8S-trihydroxydec-9-en-4, 6-yne (2), 3S, 8S-dihydroxydec-9-en-4, 6-yne 1-O-β -D-glucopyranoside (3), and one new glucosyl caffeoate, 1-O-ethyl-6-O-caffeoyl-β -D-glucopyranose (4), together with 34 known compounds were isolated from Artemisia capillaris. The structures of the new compounds were determined by extensive spectroscopic analyses including 1D and 2D NMR, HRESIMS, [α]_D and CD experiments. Among them, 19 compounds showed activity inhibiting HBsAg secretion; 20 compounds showed activity inhibiting HBeAg secretion; and 25 compounds possessed inhibitory activity against HBV DNA replication according to our anti-HBV assay on HepG 2.2.15 cell line in vitro. The most active compound 12 could inhibit not only the secretions of HBsAg and HBeAg, but also HBV DNA replication with IC₅₀ values of 15.02 μM (SI = 111.3), 9.00 μM (SI = 185.9) and 12.01 μM (SI = 139.2).     

Four new diterpenoids from the roots of Euphorbia fischeriana

Four new diterpenoids (1,4,5,9), together with 7 known diterpenoids (2,3,6–8,10,11), were isolated from the roots to Euphorbia fischeriana. On the basis of 1D and 2D NMR, HR-ESI-MS spectroscopic analysis, structures of the new compounds were elucidated as 11β-hydroxy-8,14-epoxy-ent-abieta-13(15)-en-16,12-olide (1), 3,20-dihydroxy-ent-1(10), 15-rosadiene (4), 3,7-dihydroxy-ent-1(10), 15-rosadiene (5), ingenol 6,7-epoxy-3- tetradecanoate (9). The compounds isolated were evaluated for their cytotoxicity against four cancer cell lines (A549, BEL7402, HCT116, and MDA-MB-231). Three ingenol diterpenoids (9–11) showed significant cytotoxicity against A549 with IC₅₀ value of 3.35, 2.85, 2.88 μg/mL, respectively.     

Indole alkaloids from the roots of Isatis indigotica and their inhibitory effects on nitric oxide production

Three rare indole-2-S-glycosides, indole-3-acetonitrile-2-S-β-D-glucopyranoside (1), indole-3-acetonitrile-4-methoxy-2-S-β-D-glucopyranoside (2) and N-methoxy-indole-3-acetonitrile-2-S-β-D-glucopyranoside (3), together with 11 known indole alkaloids were isolated from the roots of Isatis indigotica Fort. (Cruciferae). The structures of 1–3 were elucidated on the basis of mass spectrometry and extensive 1D and 2D NMR spectroscopy. All of the isolated compounds were tested for inhibitory activity against LPS-induced nitric oxide production in RAW 264.7 macrophages. A plausible biosynthesis pathway of 1–3 is also proposed.     

Alkyl and phenolic glycosides from Saussurea stella

One alkyl glycoside, saussurostelloside A (1), two phenolic glycosides, saussurostellosides B1 (2) and B2 (3), and 27 known compounds, including eleven flavonoids, seven phenolics, six lignans, one neolignan, one phenethyl glucoside and one fatty acid, were isolated from an ethanol extract of Saussurea stella (Asteraceae). Their structures were elucidated by NMR, MS, UV, and IR spectroscopic analysis. Of the known compounds, (+)-medioresinol-di-O-β-d-glucoside (7), picraquassioside C (10), and diosmetin-3′-O-β-d-glucoside (27) were isolated from the Asteraceae family for the first time, while (+)-pinoresinol-di-O-β-d-glucoside (6), di-O-methylcrenatin (11), protocatechuic acid (14), 1,5-di-O-caffeoylquinic acid (17), formononetin (28), and phenethyl glucoside (29) were isolated from the Saussurea genus for the first time. The anti-inflammatory activities of three new compounds (1–3), five lignans ((−)-arctiin (4), (+)-pinoresinol-4-O-β-d-glucoside (5), (+)-pinoresinol-di-O-β-d-glucoside (6), (+)-medioresinol-di-O-β-d-glucoside (7) and (+)-syringaresinol-4-O-β-d-glucoside (8)), one neolignan (picraquassioside C (10)), and one phenolic glycoside (di-O-methylcrenatin (11)) were evaluated by testing their inhibition of the release of β-glucuronidase from PAF-stimulated neutrophils. Only compound 5 showed moderate inhibition of the release of β-glucuronidase, with an inhibition ratio of 39.1%.     

Osteoclast-inhibiting saikosaponin derivatives from Bupleurum Chinense

Five new saikosaponins, saikosaponin w (1), 21β-hydroxysaikosaponin b₂ (2), 6″-O-acetylsaikosaponin e (3), 6″-O-acetylsaikosaponin b₁ (4), and 6″-O-acetylsaikosaponin b₃ (5), along with twenty-two known ones (6–27), have been isolated from the roots of Bupleurum chinense. Their structures were elucidated on the basis of detailed spectroscopic analysis, including mainly 1D and 2D NMR and HRESI-MS, qualitative chemical methods, and comparison with the literatures. Osteoclast-inhibiting activity of some of the isolated compounds was evaluated in vitro, with five ones have shown significant activity by inhibitory rates ranging from 48.3% to 56.1% at the concentration of 10 μM and with significant differences among groups observed.