Cytotoxic constituents of Abutilon indicum leaves against U87MG human glioblastoma cells

The study was aimed to identify cytotoxic leads from Abutilon indicum leaves for treating glioblastoma. The petroleum ether extract, methanol extract (AIM), chloroform and ethyl acetate sub-fractions (AIM-C and AIM-E, respectively) prepared from AIM were tested for cytotoxicity on U87MG human glioblastoma cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. These extracts exhibited considerable activity (IC₅₀ values of 42.6–64.5 μg/mL). The most active AIM-C fraction was repeatedly chromatographed to yield four known compounds, methyl trans-p-coumarate (1), methyl caffeate (2), syringic acid (3) and pinellic acid (4). Cell viability assay of 1–4 against U87MG cells indicated 2 as most active (IC₅₀ value of 8.2 μg/mL), whereas the other three compounds were much less active. Interestingly, compounds 1–4 were non-toxic towards normal human cells (HEK-293). The content of 2 in AIM-C was estimated as 3% by HPLC. Hence, presence of some more active substances besides methyl caffeate (2) in AIM-C is anticipated.     

A new butenolide cinnamate and other biological active chemical constituents from Polygonum glabrum

Phytochemical investigation of the methanol extract of the aerial parts of Polygonum glabrum afforded one new natural product ( ? )-2-methoxy-2-butenolide-3-cinnamate (1) along with six known compounds, β-hydroxyfriedalanol (2), 3-hydroxy-5-methoxystilbene (3), ( ? ) pinocembrin (4), sitosterol-(6′-O-palmitoyl)-3-O-β-d-glucopyranoside (5), ( ? ) pinocembrin-5-methyl ether (6) and sitosterol-3-O-β-d-glucopyranoside (7). Compound 1 showed promising in vitro anti-HIV-1 activity against primary isolates HIV-1_UG070 (X4, subtype D) and HIV-1_VB59 (R5, subtype C) assayed using TZM-bl cell line with IC₅₀ in the range of 15.68–22.43 μg/mL. The extract showed TI in the range of 19.19–27.37 with IC₅₀ in the range of 10.90–15.55 μg/mL. Compounds 1, 3 and 4 exhibited in vitro anti-mycobacterium activity against Mycobacterium tuberculosis H37Ra with IC₅₀ values of 1.43, 3.33 and 1.11 μg/mL in dormant phase and 2.27, 3.33 and 1.21 μg/mL in active phase, respectively. Compound 4 was found to be the most active antiproliferative with IC₅₀ values of 1.88–11.00 μg/mL against THP-1, A549, Panc-1, HeLa and MCF7 cell lines.     

Sesquiterpene lactones from Centaurea rhizantha C.A. Meyer

Two new sesquiterpene lactones, rhizantholide A (1) and rhizantholide B (2), together with five known compounds (3-7) have been isolated from the aerial parts of Centaurea rhizantha (Asteraceae). Sesquiterpene lactones belong to guaianolide class, and rhizantholide B is a rare guaianolide characterized by a free primary alcoholic function at C-10 along with a 3β,10β-epoxy function. Their structures have been established on the basis of 1D and 2D NMR experiments, as well as HR-ESIMS. The antimicrobial activity of compounds 1-7 has been evaluated against Gram-positive and Gram-negative strains. Only deacylcynaropicrin 8-O-[3′-hydroxy-2′-methylpropionate] (5) showed moderate antibacterial activity against Staphylococcus aureus with a MIC/MBC value of 500 μg/mL. All isolated compounds have been also evaluated for their cytotoxic activities against cancer cells. Among them, compound 5 showed the highest cytotoxic activity with IC₅₀ values in the range 5.02–16.76 μg/mL.     

Two new compounds from cultures of the basidiomycete Antrodiella albocinnamomea

A new linear triterpene (1), and a new sesquiterpene (2), together with a known compound methyl indole-3-carboxylate (3) were isolated from the crude extract of Antrodiella albocinnamomea. The structures of the new compounds 1–2 were determined by comprehensive spectroscopic analysis. Compound 1 exhibited signi?cant inhibitory activities against protein tyrosine phosphatase 1B (PTP1B) with IC₅₀ value of 1.0 μg/mL.     

Structure activity relationship of bergenin,p-hydroxybenzoyl bergenin, 11-O-galloylbergenin as potent antioxidant and urease inhibitor isolated from Bergenia ligulata

Ethanol extract of the aerial parts of Bergenia ligulata was subjected to solvent–solvent separation followed by various chromatographic techniques that lead to isolation of bergenine (1), p-hydroxybenzoyl bergenin (2), 11-O-galloylbergenin (3) and methyl gallate (4) as major constituents. Ethyl acetate fraction showed a dose-dependent urease inhibitory pattern with IC₅₀ value of 54μg/mL. Structures of compounds 1 and 3 were established by XRD and 2, 4 by NMR. All these compounds were subjected to DPPH scavenging activity, reducing power assay and urease inhibitory activity. The EC₅₀ 7.45 ± 0.2 μg/mL and 5.39 ± 0.28 μg/mL values in terms of antioxidant and reducing power, respectively, were less for 3. Compounds 1–3 showed moderate to significant urease inhibitory potential with IC₅₀ 57.1 ± 0.7, IC₅₀ 48.4 ± 0.3 and 38.6 ± 1.5. Antioxidant activities and urease inhibitory potential were investigated and compound 3 was found to be the most active.     

Isolation and identification of new anthraquinones from Rhamnus alaternus L and evaluation of their free radical scavenging activity

From the butanolic and the ethyl acetate extracts of Rhamnus alaternus L root bark and leaves, three new anthraquinone glycosides, alaternosides A-C (1,4,6,8 tetrahydroxy-3 methyl anthraquinone 1-O-ß-D-glucopyranosyl-4,6-di-O-α-L-rhamnopyranoside (1); 1,2,6,8 tetrahydroxy-3 methyl anthraquinone 8-O-ß-D-glucopyranoside (2) and 1, 6 dihydroxy-3 methyl 6 [2′-Me (heptoxy)] anthraquinone (3)) were isolated and elucidated together with the two known anthraquinone glycosides, Physcion-8-O-rutinoside (4) and emodin-6-O-α-L-rhamnoside (5) as well as with the known kaempferol-7-methylether (6), β-sitosterol (7) and β-sitosterol-3-O-glycoside (8). Their chemical structures were elucidated using spectroscopic methods (1D-, 2D-NMR and FAB-MS). Free radical scavenging activity of the isolated compounds was evaluated by their ability to scavenge DPPH^. free radicals. Compounds (3), (4) and (6) showed the highest activity with IC₅₀ values of 9.46, 27.68 and 2.35 μg/mL, respectively.     

Activity-guided investigation of Carissa carandas (L.) roots for anti-inflammatory constituents

The present study was structured to investigate the anti-inflammatory potential of the extracts, fractions and compounds isolated from Carissa carandas (L.) roots. Bioassay guided fractionation of methanol extract based on inhibitory potential towards proinflammatory mediators (TNF-α, IL-1β and nitric oxide (NO)) led to the identification of stigmasterol (1), lupeol (2), oleanolic acid (3), carissone (4) and scopoletin (5) as potential anti-inflammatory agents. Carissone (4) (IC₅₀ = 20.1 ± 2.69 μg/mL) and scopoletin (5) (IC₅₀ = 24.6 ± 1.36 μg/mL) exhibited significant inhibition of NO production comparable to specific NO inhibitor (L-NAME; IC₅₀ = 19.82 ± 1.64 μg/mL) without affecting the cell viability. Also, 4 and 5 at a concentration of 30 μM were found to inhibit 41.88–53.44% of TNF-α and IL-1β. To the best of our knowledge, this is the first report displaying the anti-inflammatory effects of C. carandas (L.) roots, partially mediated by inhibition of TNF-α, IL-1β and NO.     

Antifungal activity of cinnamic acid and benzoic acid esters against Candida albicans strains

Candida albicans is an important opportunistic fungal pathogen capable of provoking infection in humans. In the present study, we evaluated the antifungal effect of 23 ester derivatives of the cinnamic and benzoic acids against 3 C. albicans strains (ATCC-76645, LM-106 and LM-23), as well as discuss their Structure–Activity Relationship (SAR). The antifungal assay results revealed that the screened compounds exhibited different levels of activity depending on structural variation. Among the ester analogues, methyl caffeate (5) and methyl 2-nitrocinnamate (10) were the analogues that presented the best antifungal effect against all C. albicans strains, presenting the same MIC values (MIC = 128 μg/mL), followed by methyl biphenyl-2-carboxylate (21) (MIC = 128, 128 and 256 μg/mL for C. albicans LM-106, LM-23, and ATCC-76645, respectively). Our results suggest that certain molecular characteristics are important for the antifungal action.     

A new antifungal and antiprotozoal bibenzyl derivative from Gavilea lutea

A new bibenzyl derivative (4), together with two glycosylated flavonoids (1 and 2), batatasin III (3) and the phenanthrene isohircinol (5) were isolated from the aerial parts of Gavilea lutea. Their structures were elucidated on the basis of spectroscopic studies including 1D and 2D NMR, UV, IR and HRESIMS. All isolated compounds were evaluated for their antifungal activity towards Candida albicans. The new compound 4 showed inhibitory activity with a MIQ of 50 μg. In addition, compound 4 exhibited a selective activity (IC₅₀ = 2.3 μg/mL) against Leishmania donovani.     

New compound from Euphorbia alatavica Boiss

One new compound alatavinol (1), together with five known compounds, kaempferol (2), quercetin (3), laricircsinol (4), secoisolariciresinol (5) and loliolide (6) were isolated from the whole plant of Euphorbia alatavica Boiss. Those compounds were isolated and purified by various column chromatographic methods and their structures were elucidated by spectroscopic (1D, 2D NMR, and HR-MS) chemical analyses. All compounds were isolated for the first time from E. alatavica Boiss, and biochemical pathway of the new compound has been hypothesized. Furthermore, these compounds were evaluated for antioxidant properties based on the DPPH radical scavenging activities. Results showed that IC₅₀ values of compounds 1, 3, 4, 5 and 6 were 25.69, 1.88, 2.87, 11.55 and 17.81 μg/mL, respectively, as compared to the control ascorbic acid (5.34 μg/mL).     

Carbazole-pyranocoumarin conjugate and two carbazole alkaloids from the stems of Clausena excavata

A carbazole-pyranocoumarin conjugate, carbazomarin B (1), and two carbazole alkaloids, 6-methoxymukonidine (2) and 2-hydroxy-3-methoxycarbazole (3), together with 27 known compounds (4–30), were isolated from the stems of Clausena excavata. Their structures have been elucidated by spectroscopic analyses. Compound 2 showed moderate cytotoxicity to HuCCA-1, MOLT-3 and HepG2 cancer cell lines with IC₅₀ values of 15.09–28.50 μg/mL, but none to A549 cell line. Heptaphylline (6) and nordentatin (23) were found to show moderate cytotoxic activity against HepG2 cell line with IC₅₀ values of 12.33 and 11.33, respectively, while clausine K (27) exhibited strong cytotoxicity with IC₅₀ value of 1.05 μg/mL, better than a standard drug (etoposide, IC₅₀ 13.40 μg/mL).     

Coumarins and alkaloids from the roots of Toddalia asiatica

The EtOAc and MeOH extracts of the roots of Toddalia asiatica Lam. were investigated for the roots’ chemical constituents. Two new compounds including 2′R-acetoxytoddanol (1) and 8S-10-O-demethylbocconoline (3) as well as 15 known compounds were isolated. Compound 10 showed strong cytotoxicity against KB cells with an IC₅₀ value of 2.60 μg/mL, which is nearly equal to the ellipticine standard, but showed no activity against Vero cells. Alkaloid 3 displayed weak cytotoxicity against the KB cell line with an IC₅₀ value of 21.69 μg/mL.     

A new caffeic acid tetramer from the Dracocephalum moldavica L.

A new caffeic acid tetramer compound, named (+) methyl rabdosiin (4), together with seven known caffeic acid multimers (1–3, 5–8) and one caffeic acid monomer (9), were isolated from the aerial parts of Dracocephalum moldavica L. The structures of these compounds were assigned on the basis of 1D and 2D NMR spectroscopic and mass spectrometry analyses. The protective effects of compounds 2–4 against hydrogen peroxide (H₂O₂)-induced apoptosis were evaluated in primary cardiomyocytes of SD neonatal rats in vitro by the MTT method. Three compounds exhibited potent protective activities at 12.5 μg/mL.     

A new antimicrobial and radical-scavenging glycoside from Paullinia pinnata var. cameroonensis

A new glycoside, pinnatoside A (1), together with two known compounds (2 and 3), were isolated from the stems of Paullinia pinnata. Their structures were elucidated on the basis of extensive spectroscopic analysis and chemical methods. Compound 1 showed significant antibacterial activity with a minimum inhibitory concentration (MIC) value of 1.56 μg/mL against Escherichia coli, and 2 displayed significant antibacterial activity with a MIC value of 1.56 μg/mL against Enterobacter aerogenes and E. coli. Equally, compound 1 exhibited the best radical-scavenging activity (RSa₅₀ = 25.07 ± 0.49 μg/mL).     

A new sesquiterpene from the entomogenous fungus Phomopsis amygdali

A new sesquiterpene, (+)-S-1-methyl-abscisic-6-acid (1), together with five known compounds, (+)-S-abscisic acid (2), fusicoccin J (3), 3α-hydroxyfusicoccin J (4), (R)-5-hydroxymethylmellein (5) and 4-hydroxyphenethyl acetate (6) was isolated from the fermentation extract of Phomopsis amygdali, an entomogenous fungus isolated from Call midge. Their structures were determined mainly by analysis of MS and NMR spectroscopic data. Compounds 1–6 were tested for antimicrobial activity against three plant pathogenic fungi: Gibberella zeae, Verticillium albo-atrum, and Fusarium nivale, and two bacteria: Escherichia coli and Pseudomonas aeruginosa 2033E. As a result, compounds 1–4 displayed antibacterial activity against Gram-negative P. aeruginosa 2033E, and the minimum inhibition concentration (MIC value) of 1–4 is 30 μg/mL, 58 μg/mL, 26 μg/mL, and 26 μg/mL, respectively.     

Alpha-glucosidase inhibitory activity of ethanol extract,fractions and purified compounds from the wood of Albizia myriophylla

Albizia myriophylla Benth. is a medicinal herb which is used as a traditional remedy for various ailments including diabetes in Thailand. In our continued investigation of the biological activity of A. myriophylla, the ethanol extract, fractions and the isolated compounds from the wood of this plant were evaluated for in vitro α-glucosidase inhibition using spectrophotometric method. The plant ethanol extract and its different fractions possessed α-glucosidase inhibitory activity in a concentration-dependent manner. Dichloromethane fraction of the wood ethanol extract exhibited the highest percent inhibition against α-glucosidase (69.30%) among all fractions. Subsequent α-glucosidase inhibition assay proved that indenoic acid (1), 8-methoxy-7, 3′,4′-trihydroxyflavone (2) and 3,4,7,3′-tetrahydroxyflavan (3) were partially rational for antidiabetic effect of this plant species. Among these compounds, 3 (IC₅₀ 98.59 μg/mL) exhibited potent inhibition of α-glucosidase, compared with a positive control acarbose (IC₅₀ 125 μg/mL). The inhibitory effect towards α-glucosidase of compounds 1–3 was reported herein for the first time.     

Phytochemical constituents and antioxidant activity of Echinops albicaulis

Two thiophenes; 5-(3-buten-1-ynyl)-2,2′-bithiophene (2) and α-tertthienyl (9), two alkaloids; echinopsine (10) and echinorine (11), three flavonoids; genkwanin (5), apigenin (6), and rutin (7), two triterpenoids; lupeol acetate (1) and lupeol linoleate (4), together with 2,6,10-trimethyldodeca-2,6,10-triene (4) and β-sitosterol glucoside (8) were isolated from the aerial parts of Echinops albicaulis. Antioxidant, antimicrobial and antiprotozoal activities were evaluated. E. albicaulis aqueous methanolic extract (50, 10, and 1 mg/mL) showed significant antioxidant activity comparable to the potent antioxidant, N-acetyl cysteine, moreover, the aqueous methanolic extract (1 mg/mL) significantly reduced intracellular reactive oxygen species in active cell cultures of human peripheral blood mononuclear cells under oxidative stress more than the reference antioxidant N-acetyl cysteine. None of the isolated compounds showed antimicrobial or antiprotozoal activities at concentration up to 20 μg/mL.     

Cytotoxic constituents from Vicia monantha subsp. monantha seeds

Chemical investigation of Vicia monantha subsp. monantha Retz. revealed isolation of one new hydroxy- fatty acid (6) identified as (6-Z, 10-E)-9-hydroxy henicosa-6,10-dienoic acid in addition to six known metabolites; hexadecanoic acid (1), β-sitosterol (2), β-amyrin (3), β-sitosterol-glucoside (4), 2,3-dihydroxypropyl tetradecanoate (5) and (Z)-9-hydroxypentadec-6-enoic acid (7). The cytotoxic effect of the isolated compounds was assessed by MTT assay using lung cancer A-549, prostate cancer PC3, breast cancer MCF-7, colon cancer HCT-116 and liver cancer HepG2 cell lines. Only compounds 1, 2, and 4 showed cytotoxic effect on HCT-116 cells where compound 2 was the most active with IC₅₀ value of 22.61 μg/mL. In addition, compounds 1, 2, 3, and 4 showed promising cytotoxic effect on MCF-7 cells with IC₅₀ values of 21.03, 15.42, 10.089, and 11.34 μg/mL, respectively.     

Structures and bioactivities of seven flavonoids from Osmanthus fragrans ‘Jinqiu’ essential oil extraction residues

Osmanthus fragrans are well-known for their fragrance, but it is wasteful if to discard O. fragrans flower after extracting their essential oils. In this paper, we found that O. fragrans flower residues were rich in flavonoids. Six flavonoids and one phenylethanoid glycoside were isolated from the ethanol extract of O. fragrans flower residues, identified as quercetin (1), rutin (2), verbascoside (3), genistin (4), kaempferol (5), isorhamnetin (6) and naringin (7). In bioactivity study, kaempferol (IC₅₀ = 1.43 μg/mL) showed the best anti-inflammatory activity. Isorhamnetin, quercetin, kaempferol, verbascoside and rutin (the values of IC₅₀ were 18.30, 11.05, 16.88, 20.21 and 22.76 μg/mL, respectively) showed excellent DPPH free radical scavenging activity. Verbascoside performed relatively well at inhibiting the growth of both CT26 colonic carcinoma cells (IC₅₀ = 46.87 μg/mL) and HepG2 hepatocarcinoma cells (IC₅₀ = 30.58 μg/mL). In addition, quercetin and kaempferol showed strong anti-proliferation activity against HepG2 cells.     

Phenanthrenes from Arundina graminifolia and in vitro evaluation of their antibacterial and anti-haemolytic properties

Chemical investigation and activity test of Arundina graminifolia led to the isolation of six phenanthrenes: blestriarene A (1), shancidin (2), densiflorol B (3), ephemeranthoquinone (4), coelonin (5) and lusianthridin (6). The isolated compounds demonstrated antibacterial and anti-haemolytic activities. It was found that compounds 1 and 2 had medium antibacterial activity against Staphylococcus aureus, Bacillus subtilis and Escherichia coli, with MICs of 20–40 μg/mL and MBCs of 40–320 μg/mL. Bactericidal mechanisms were explored. Rupture of cell wall and membrane and leakage of nuclear mass were observed by transmission electron microscopy (TEM). Moreover, compounds 1–3 attenuated the erythrocyte damage. Compounds 1 and 2 showed significant anti-haemolytic activity with inhibition rate about 50% at 16 μg/mL.