Bioactivity-guided chemical analysis of Melia azedarach L. (Meliaceae), displaying antidiabetic activity

One new Euphane-type triterpenoid 3β-hydroxytirucalla-5, 24-dien-21-oic acid (1), and ten known compounds (2–11) were isolated from Melia azedarach L. through bioassay-guided chemical analysis. The structures of the isolated compounds were established by means of 1D and 2D NMR spectroscopic (¹H, ¹³C, DEPT, COSY, HSQC and HMBC) and MS spectral analyses. All the fractions and isolated pure compounds were evaluated for antidiabetic activity by determining their inhibitory effects on PTP-1B enzyme as well as glucose uptake stimulation in C₂Cl₂ myoblasts cells. Compounds 4 and 7 showed significant in vitro PTP-1B inhibitory activity with 69.2 and 66.8% inhibition at 10 μg/ml concentrations respectively.     

Chemical constituents of Swertia yunnanensis and their anti-hepatitis B virus activity

Four new triterpenoids, sweriyunnangenin A (1), sweriyunnanosides A (2), B (3) and C (4), along with nineteen known compounds (5–23) were isolated from Swertia yunnanensis. Based on extensive spectroscopic analyses (1D- and 2D-NMR, HRESIMS, UV, IR, [α]_D), the structures of sweriyunnangenin A (1), sweriyunnanosides A (2), B (3) and C (4) were elucidated as taraxer-14-ene-3α,6β-diol, oleanolic acid 28-O-β-d-glucopyranosyl-(1 → 2)-O-β-d-glucopyranoside, 2α,3β-di-hydroxyolean-12-en-28-oic acid 28-O-β-d-glucopyranosyl(1 → 6)-β-d-glucopyranosyl (1 → 6)-β-d-glucopyranosyl(1 → 2)-β-d-glucopyranoside and hederagenin 28-O-β-d-glucopyranosyl(1 → 6)-β-d-glucopyranosyl(1 → 6)-β-d-glucopyranosyl(1 → 2)-β-d-glucopyranoside, respectively. Twenty-two compounds were evaluated for their anti-HBV activities on the HepG 2.2.15 cell line in vitro, of which nine compounds showed potent anti-HBV activities. Compounds 1, 5–6, 14–16 and 19 showed activities against the secretion of HBsAg (IC₅₀ values from 0.10 to 1.76 mM) and HBeAg (IC₅₀ values from 0.04 to 1.41 mM), and compounds 11 and 13–16 exhibited significant inhibition on HBV DNA replication (IC₅₀ values from 0.01 to 0.09 mM).     

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.     

Antioxidant xanthones from Swertia mussotii,a high altitude plant

Four new xanthones, 3,5,6,8-tetrahydroxyxanthone-1-C-β-d-glucoside (1), 7-hydroxy-3,4,8-trimethoxyxanthone-1-O-(β-d-glucoside) (2), 6-hydroxy-3,5-dimethoxyxanthone-1-O-(β-d-glucoside) (3), 3,4,7,8-tetramethoxyxanthone-1-O-(β-d-glucoside) (4), together with twenty-one known xanthones (5–25) were isolated from the ethanol aqueous extract of Swertia mussotii. Their structures were elucidated via spectroscopic analyses. Oxygen radical absorbance capacity of all the isolated xanthones was systematically evaluated by ORAC_FL assay. Results disclose that all the tested xanthones display moderate to excellent antioxidant activity, where 1 is the most active compound and 13 is the least one. A preliminary structure–activity relationship is also discussed.     

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.     

Sinoscrewtine,an alkaloid with novel skeleton from the roots of Sinomenium acutum

An alkaloid with novel skeleton, sinoscrewtine (1), has been isolated from the roots of Sinomenium acutum. Its structure was established by spectral analysis and X-ray crystallographic study, and its possible biosynthetic pathway was delivered. In vitro experiments, 1 showed weak injurious effects against H₂O₂/Aβ_25–35 induced oxidative injury in PC-12 cells and DPPH radical scavenging activity with IC₅₀ of 32.6 μM.     

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).     

Racemosins A and B,two novel bisindole alkaloids from the green alga Caulerpa racemosa

Racemosin A (1), a structurally unique bisindole alkaloid possessing the seco-indolo[3,2-a]carbazole skeleton with two uncommon indolinenone units both conjugated with a methyl propenoate moiety, and its unusual cyclized derivative, racemosin B (2), were isolated from the green alga Caulerpa racemosa, together with the most commonly encountered pigment in the genus Caulerpa, caulerpin (3). Their structures were elucidated by extensive spectroscopic analysis and by comparison with data for related known compounds. A plausible biosynthetic pathway of 1 and 2 was proposed. In a neuro-protective assay, compound 1 significantly attenuated the Aβ_25–35-induced SH-SY5Y cell damage with a 14.6% increase in cell viability at the concentration of 10 μM when compared to epigallocatechin gallate (EGCG, 16.57% increase at 10 μM) as the positive control.     

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.     

Cytotoxic effect of triterpenoids from the root bark of Hibiscus syriacus

In this study, 4 new triterpenoids—3β- acetoxy-olean-11-en,28,13β-olide (1), 3β- acetoxy-11α,12α-epoxy-olean-28,13β-olide (2), 19α-epi-betulin (3), and 20, 28-epoxy-17β,19β-lupan-3β-ol (4)—and 12 known compounds, were isolated from the root bark of Hibiscus syriacus L. by using acetone extraction. Their structures were characterized by extensive spectroscopic analysis. To investigate cytotoxicity, A549 human lung cancer cells were exposed to the extract and the compounds identified from it. Significantly reduced cell viability was observed with betulin-3-caffeate (12) (IC₅₀, 4.3 μM). The results of this study indicate that betulin-3-caffeate (12) identified from H. syriacus L. may warrant further investigation for potential as anticancer therapies.     

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.     

Cucurbitane-type triterpenoids from the stems and leaves of Momordica charantia

Six new cucurbitane-type triterpenoids, karavilagenin F (1), karavilosides XII and XIII (2, 3), momordicines VI, VII, and VIII (4, 5 and 6), along with four known ones, 5β,19-epoxy-25-methoxycucurbita-6,23-diene-3β,19-diol (7), 5β,19-epoxycucurbita-6, 23-diene-3β,19,25-triol (8), kuguacin R (9), and (19R,23E)-5β,19-epoxy-19-methoxycucurbita-6,23,25-trien-3β-ol (10), were isolated from the stems and leaves of Momordica charantia L. Their chemical structures were elucidated by extensive 1D NMR and 2D NMR (HSQC, HMBC, COSY, and ROESY), MS experiments, and CD spectrum. Compound 6 showed weak cytotoxicity against five human cancer cells lines with IC₅₀ values of 14.3–20.5 μmol/L.     

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%.     

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.     

Lanostane-type triterpenoid and steroid from the stem bark of Klainedoxa gabonensis

A new lanostane triterpenoid, 2-hydroxy-24-methylenelanostan-1,8-dien-3-one named klainedoxalanostenone (1) with one new steroid, 6-O-acyl-β-d-glucosyl-β-sitosterol named klainedoxasterol (2) together with ten known compounds including six triterpenoids (3–8), two steroids (9, 10) and two tanins (11, 12) were isolated from the stem bark of Klainedoxa gabonensis. To the best of our knowledge, this is the first report of lanostane-type triterpenoids from this genus. Their structures were determined by extensive analysis of spectroscopic data (1D and 2D NMR, MS) and by comparison with literature data. The xanthine oxidase inhibitory activity of nine compounds (1–6, 8, 10 and 11) were evaluated. Compound 5 showed a good xanthine oxidase inhibitory activity; the other tested compounds were moderately active.     

Sesquiterpene lactones from Mikania micrantha and Mikania cordifolia and their cytotoxic and anti-inflammatory evaluation

The guaianolide 8-epi-mikanokryptin (1) and the melampolide 11Hβ-11,13-dihydromicrantholide (2) along with known sesquiterpene lactones (3–13) and other constituents were isolated from the aerial parts of different populations of Mikania micrantha and Mikania cordifolia collected in several states of Mexico. The relative and absolute configurations of 1 were determined by X-ray diffraction and CD analysis, respectively. Considering the ¹H and ¹³C NMR chemical shift similarities and the H–H coupling constant values, a [¹D¹⁴, ¹⁵D₅] conformation was established for micrantholides (2, 8–13). We tested nearly all the sesquiterpene lactones for antiproliferative activity in human cancer cell lines, and they exhibited moderate activity. Additionally, in a mouse ear model of edema induced by TPA, the anti-inflammatory activities were marginal.     

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.     

Microbial transformation of ginsenoside-Rg₁ by Absidia coerulea and the reversal activity of the metabolites towards multi-drug resistant tumor cells

Biotransformation of ginsenoside-Rg₁ (1) by the fungus Absidia coerulea AS 3.2462 yielded five metabolites (2? 6). On the basis of spectroscopic data analyses, the metabolites were identified as ginsenoside-F₁ (2), 6α,12β-dihydroxydammar-3-one-20(S)-O-β-D-glucopyranoside (3), 3-oxo-20(S)-protopanaxatriol (4), 3-oxo-7β-hydroxy-20(S)-protopanaxatriol (5), and 3-oxo-7β,15α-dihydroxy-20(S)-protopanaxatriol (6), respectively. Among them, 5 and 6 are new compounds. These results indicated that Absidia coerulea AS 3.2462 could catalyze the specific C-3 dehydrogenation of derivatives of ginsenoside-Rg₁, as well as hydroxylation at the 7β and 15α positions. Metabolites 2, 4 and 5 exhibited moderate reversal activity towards A549/taxol MDR tumor cells in vitro.     

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.     

Triterpenoids of Chrysosplenium carnosum

A phytochemical study of the ethanolic extract of Chrysosplenium carnosum Hook. f. et Thoms. led to the isolation of two new oleanane-type triterpenoids, 6β-hydroxy-3-oxoolean-12-en-27-oic acid (1) and 3β, 21α-dihydroxyolean-12-en-27-oic acid (2), along with fourteen known compounds (3–16), all of which were isolated from this plant for the first time. The structures of these compounds were established on the basis of spectroscopic methods. Compounds 1–4 were evaluated for their in vitro anti-tumor activities on B16F10, SP2/0 and Hep-G2 cells lines. Compounds 1, 3 and 4 exhibited strong inhibitory activity against B16F10 and SP2/0 cells' growth, compared with moderate cytotoxic activity against Hep-G2 cells. However, compound 2 showed to be inactive against these tumor cells.