Bioactive phenolics from the fruits of Livistona chinensis

This study investigated the antioxidant and cytotoxic activity of the phenolics isolated from the fruits of Livistona chinensis. Four new compounds, 1-{ω-isoferul[6- (4-hydroxybutyl)pentadecanoic acid]}-glycerol (1), E-[6′-(5″-hydroxypentyl)tricosyl]-4-hydroxy-3-methoxycinnamate (2), 2-(3′-hydroxy-5′-methoxyphenyl)-3-hydroxylmethyl-7-methoxy-2,3-dihydrobenzofuran-5- carboxylic acid (3), 7-hydroxy-5,4′-dimethoxy-2-arylbenzofuran (4), together with eleven known phenolics (5-15), were isolated and identified. Among these compounds, 1-4, 5-O-caffeoylshikimic acid (5), caffeic acid (7), and 3-O-caffeoylshikimic acid (8) showed potent antioxidant activity. 1-5, and 8 showed potent antiproliferative activities with IC₅₀ values among 5-150 μM against HepG2 human liver cancer, HL-60 human myeloid leukemia, K562 human myeloid leukemia, and CNE-1 human nasopharyngeal carcinoma cell lines. On the basis of these findings, it could be proposed that the fruits of L. chinensis may serve as attractive mines of powerful anticancer and antioxidant agents for various purposes.     

Rigenolide A,a new secoiridoid glucoside with a cyclobutane skeleton,and three new acylated secoiridoid glucosides from Gentiana rigescens Franch

Rigenolide A (1), a new secoiridoid glucoside with a cyclobutane skeleton and three new acylated secoiridoid glucosides, 2′-(2,3-dihydroxybenzoyl)-gentiopicroside (2), 2′-(2,3-dihydroxybenzoyl)-swertiamarin (3), 3′-(2,3-dihydroxybenzoyl)-sweroside (4), along with two noriridoids (7 and 8) and two known secoiridoid glucosides (5 and 6), were isolated from Gentiana rigescens Franch. The structures of new compounds were elucidated by extensive spectroscopic analyses. The isolated compounds were evaluated for DPPH free-radical scavenging activity.     

Homoisoflavanones from Ledebouria floribunda

The bulbs of Ledebouria floribunda (Baker) Jessop have yielded two novel compounds, 7-O-[α-rhamnopyranosyl-(1→6)-β-glucopiranosyl]-5-hydroxy-3-(4-methoxybenzyl)-chroman-4-one (1) and 7-O-[α-rhamnopyranosyl-(1→6)-β-glucopiranosyl]-5-hydroxy-3-(4′-hydroxybenzyl)-chroman-4-one (2) along with five other known compounds, 5,7-dihydroxy-3-(4′-methoxybenzyl)-chroman-4-one or 3,9-dihidroeucomin (3), 5,7-dihidroxy-6-methoxy-3-(4′-methoxybenzyl)-chroman-4-one (4), 5,7-dihidroxy 3-(4′-hydroxybenzyl)-chroman-4-one or 4,4′-demethyl-3,9-dihydropuctatin (5), 5,7-dihidroxy-3-(4′-hydroxybenzyl)-6-methoxy-chroman-4-one or 3,9-dihydroeucomnalin (6) and 7-hydroxy-3-(4′-hydroxybenzyl)-5-methoxy-chroman-4-one (7). Their structures were elucidated by spectra analysis. The seven homoisoflavanones were found to be antioxidant against DPPH radical and β-carotene/linoleic acid system.     

Isolation of new flavan-3-ol and lignan glucoside from Loropetalum chinense and their antimicrobial activities

Phytochemical and antimicrobial activity study on the ethanol extract of the leaves and stems of Loropetalum chinense led to the isolation of a new flavan-3-ol compounds, 8-[1-(3,4-dihydroxyphenyl)-3-methoxy-3-oxopropyl]-catechin (loropetaliside A) (1) and a new lignan glucoside, 1-(5-hydroxy-3-methoxyphenyl)-2-(2-β-glucopyranosyl-4-hydroxy-5-(1-(E)propen-3-ol)-phenyl)-propane-3-ol (loropetaliside B) (3) and several known compounds manglieside D (2), quercetin (4), kaempferol-3-O-D-glucopyranoside (5), quercetin-3-O-β-L-rhamnoside (6) and tiliroside (7). Their structures were elucidated on the basis of extensive spectroscopic analysis.     

Antioxidant flavonoids from Epimedium wushanense

Two new flavonoids, wushanicaritin (1) and wushankaempferol (2), along with 24 known flavonoids were isolated from the whole herb of Epimedium wushanense T.S. Ying (Berberidaceae). On the basis of NMR and ESI-MS spectroscopic analysis, structures of compounds 1 and 2 were elucidated as 8-γ-hydroxy-γ,γ-dimethylpropyl-3,5,7-trihydroxy-4′- methoxyflavone and kaempferol 3-O-α-l-[2,3-di-O-β-d-(6-E-p-coumaroyl) glucopyranosyl]-rhamnopyranosyl-7-O-α-l-rhamnopyranoside, respectively. DPPH radical scavenging activity tests indicated that 1 (IC₅₀ 35.3 μM) exhibited antioxidant activity comparable to Vitamin C (IC₅₀ 32.0 μM), while 2 (IC₅₀ 443.7 μM) showed weak activity.     

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.     

Flavonoids and stilbenoids from Derris eriocarpa

One new resveratrol analogue, 1-(3′,4′,5′-trimethoxyphenyl)-2-methoxy-2-(4″-methoxyphenyl)-ethane-1-ol (1), and two new prenylisoflavones, 4′-hydroxy-5,7-dimethoxy-6-(3-methyl-2-butenyl)-isoflavone (2), and derrubon 5-methyl ether (3), together with 17 known compounds including one new natural product, 5,7-dihydroxy-3-[4′-O-(3-methyl-2-butenyl)-phenyl]-isoflavone (4), were isolated from the stems of ethnomedicinal plant Derris eriocarpa How. (Leguminosae). Their structures were elucidated based on chemical evidence and spectroscopic techniques including two-dimensional NMR methods. All compounds are reported from this species for the first time. Antimicrobial activities of the new compounds were evaluated. Compound 2 exhibited good inhibitory activities against Candida guilliermondii, C. albicans and Microsporium gypseum with the minimal inhibitory concentration (MIC) values of 12.5 μg/ml.     

A new triglucosylated naphthalene glycoside from Aloe vera L.

A new triglucosylated naphthalene derivative, named aloveroside A (1), together with two known anthraquinone dimers and two 6-phenyl-2-pyrone derivatives, was isolated from the Aloe vera ethanolic extracts. The structure of 1 was established as 1-(((4-(1-O-β-D-glucopyranosyl -(1→4)-β-D-xylopyranoside)-hydroxymethyl)-1-hydroxy-8-O-α-L-rhamnopyranoside)naphthalene-2-yl)-ethanone by means of spectroscopic evidences and chemical methods. All these compounds were tested for their BACE inhibitory activity but no significant activities were found.     

Three new phenolic compounds from the roots of Glycyrrhiza yunnanensis

Three new phenolic compounds (1–3), together with 16 known compounds (4–19), were isolated from the roots of Glycyrrhiza yunnanensis Cheng f. et L. K. Dai. On the basis of 1D and 2D NMR, HR-ESI-MS, and circular dichroism (CD) spectroscopic analysis, structures of the new compounds were elucidated as 2-(2′-methoxy-4′-hydroxy)-aryl-3-methy-6-hydroxy-benzofuran (1), (2S)-6,7-(2,2-dimethyldihydropyrano)-8-prenyl-4′-hydroxyflavanone (2), and 6-prenyl-7,3′,4′-trihydroxyflavone (3). Compounds 1, 3, 5, 12, 14, 15 and 16 showed antioxidant activity by an ABTS-based assay.     

Stereochemical determination of new cytochalasans from the plant endophytic fungus Trichoderma gamsii

Three new cytochalasans, trichalasins E (1), F (2) and H (7), together with four known analogues, trichalasin C (3), aspochalasin K (4), trichalasin G (5) and aspergillin PZ (8), were isolated from one endophytic fungus Trichoderma gamsii inhabiting in the traditional medicinal plant Panax notoginseng (BurK.) F.H. Chen. Trichalasins E (1) contains a unique hydroperoxyl group, which is the first report in all known analogues, whereas trichalasin H (7) possesses the rare 6/5/6/6/5 pentacyclic skeleton with 12-oxatricyclo [6.3.1.0^2,7] moiety as that of aspergillin PZ (8). The relative configurations of the new compounds were characterized by analysis of coupling constants and ROESY correlations, and the absolute configurations of trichalasins E (1), H (7) and aspergillin PZ (8) were determined by modified Mosher’s reaction. In addition, compounds 1–5, 7 and 8 were tested cytotoxic activities against several cancer cell lines.     

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.     

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.     

Glycosylsphingolipids from Euonymus japonicus Thunb

The stem bark of Euonymus japonicus Thunb. led to the isolation of three new glycosylsphingolipids (1–3), 1-O-[-L-rhamnopyranosyl-(1 → 2)-β-D-glucopyranosyl]-(2S,3R,9E)-2-N-[(2R)-hydroxystearoyl]-octadecasphinga-9-ene (euojaposphingoside A, 1), 1-O-[β-D-glucopyranosyl-(1 → 2)-β-D-glucopyranosyl]-(2S,3R,4R,11E)-2-N-[(2R)-hydroxydocasanoyl]-octadecasphinga-11-ene (euojaposphingoside B, 2), 1-O-[β-D-glucopyranosyl]-2′-O-[β-D-glucopyranosyl]-(2S,3R,4R,11E)-2-N-[(2R)-hydroxytetracosanoyl]-octadecasphinga-11-ene (euojaposphingoside C, 3) along with three known glycosylsphingolipids (4–6), 1-O-[β-D-glucopyranosyl]-(2S,3R,9E)-3-hydroxymethyl-2-N-[(2R)-hydroxynonacosanoyl)-tridecasphinga-9-ene (4), 1-O-[β-D-glucopyranosyl]-(2S,3R,9E,12E)-2-N-[(2R)-hydroxytetracosanoyl] octadecasphinga-9,12–diene (5), 1-O-[β-D-glucopyranosyl]-(2S,3R,5R,9E)-2-N-[tridecanoyl] nonacosasphinga-9-ene (6), lupeol (7), stigmasterol (8), sitosterol (β and α) (9,10) and β-carotene (11). The structure of all the compounds was achieved by spectroscopic and chemical data analysis. The antiplasmodial, antileismanial and cytotoxic activity of all compounds was tested.     

Dammarane-type glycosides and long chain sesquiterpene glycosides from Gynostemma yixingense

A new dammarane-type glycoside and a new long chain sesquiterpene glycoside, along with nine known compounds 20(S)-ginsenoside Rh1 (3), 20(R)-ginsenoside Rh1 (4), ginsenoside F1 (5), amarantholidoside IV (6), ginsenoside Rc (7), 20(S)-ginsenoside Rg2 (8), 20(R)-ginsenoside Rg2 (9), ginsenoside Rd (10) and gypenoside XLVI (11) were isolated from Gynostemma yixingense. The structures of the new compounds were determined on the basis of spectroscopic analysis, including 1D-, 2D-NMR and ESI-MS techniques as well as by comparison of the spectral data with those of related compounds as 2α,3β,20(S)-trihydroxydammar-24-ene-3-O-[β-d-glucopyranosyl((1 → 2)-β-d-glucopyranosyl]-20-O-[β-d-xylopyranosyl((1 → 6)-β-d-glucopyranoside] (1) (2E,6E)-10-β-d-glucopyranosyl-1,10,11-trihydroxy-3,7,11-trimethyldodeca-2,6-diene (2).     

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.     

Glycocerebroside bearing a novel long-chain base from Sagina japonica (Caryophyllaceae)

A new glycocerebroside (1), along with one reported one (2), was isolated from the ethanol extract of Sagina japonica (Caryophyllaceae) and was fully characterized. The structures of two compounds were identified as (2S, 3S, 4R, 8E)-1-(β-D-glucopyranosyl-3, 4-dihydroxy-2-[(R)-2′- hydroxypalmitoyl]amino-8-heptadecaene (1) and (2S, 3R, 8E)-1-(β-D-glucopyranosyl-3-hydroxy-2-[(R)-2′-hydroxypalmitoyl]amino-8-octadecaene (2) by using spectroscopic methods (¹H, ¹³C, and 2D NMR, MS) and chemical degradation.     

Cytotoxic steroidal glycosides from Allium flavum

Three new spirostane-type glycosides (1–3) were isolated from the whole plant of Allium flavum. Their structures were elucidated mainly by 2D NMR spectroscopic analysis and mass spectrometry as (20S,25R)-2α-hydroxyspirost-5-en-3β-yl O-β-d-xylopyranosyl-(1 → 3)-[β-d-galactopyranosyl-(1→2)]-β-d-galactopyranosyl-(1→4)-β-d-galactopyranoside (1), (20S,25R)-2α-hydroxyspirost-5-en-3β-yl O-β-d-xylopyranosyl-(1 → 3)-[β-d-glucopyranosyl-(1→2)]-β-d-galactopyranosyl-(1→4)-β-d-galactopyranoside (2), and (20S,25R)-spirost-5-en-3β-yl O-α-l-rhamnopyranosyl-(1 → 4)-[β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (3). The three saponins were evaluated for cytotoxicity against a human cancer cell line (colorectal SW480).     

Novel NGF-potentiating limonoids from the fruits of Melia toosendan

Four new limonoids (1–4), together with five known limonoids (5–9), were isolated from the fruits of Melia toosendan. Their structures were elucidated based on extensive spectroscopic analyses (1D- and 2D-NMR, HRESIMS, IR, [α]_D). The isolated compounds were evaluated for their neurite outgrowth-promoting activities. Compounds 2 and 6 significantly enhanced NGF-mediated neurite outgrowth in PC12 cells at concentrations ranging from 0.1 to 50.0 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.     

Pregnane alkaloids from Sarcococca hookeriana var. digyna

Fourteen pregnane-type steroidal alkaloids were isolated from the ethanolic extracts of whole Sarcococca hookeriana var. digyna plants. Their structures were elucidated on the basis of spectral data. Three of them were identified as new steroidal alkaloids: (S)-20-(N,N-dimethylamino)-16α,17α-epoxy-3β-methoxy-pregn-5-ene (1), (20S)-20-(N,N-dimethylamino)-3β-tigloylamino-5α-pregn-11β-ol (2), and (20S)-2α,4β-bis(acetoxy)-20-(N,N-dimethylamino)-3β-tigloylamino-5α-pregnane (3). Some of the isolated compounds showed estrogen biosynthesis-promoting effects in human ovarian granulosa-like KGN cells. The EC₅₀ values for the most effective compounds, vagnine B (6) and funtumafrine C (12), were 71 μM and 67 μM, respectively.