HIV-1 protease and HIV-1 integrase inhibitory substances from Eclipta prostrata

The bioassay-guided fractionation for anti-HIV-1 integrase activity led to the isolation of six compounds from the whole plant extract of Eclipta prostrata extract. They were identified as 5-hydroxymethyl-(2,2':5',2')-terthienyl tiglate (1), 5-hydroxymethyl-(2,2':5',2')-terthienyl agelate (2), 5-hydroxymethyl-(2,2':5',2')-terthienyl acetate (3), ecliptal (4), orobol (5) and wedelolactone (6). Of these, compound 6 showed the highest activity against HIV-1 integrase (IN) with an IC50 value of 4.0+/-0.2 microm, followed by compound 5 (IC50=8.1+/-0.5 microm), whereas the four terthiophene compounds (1-4) were inactive (IC50>100 microm). Regarding HIV-1 protease (PR) inhibitory activity, compound 1 exhibited appreciable activity against HIV-1 PR with an IC50 of 58.3+/-0.8 microm, followed by compound 4 (IC50=83.3+/-1.6 microm) and compound 3 (IC50=93.7+/-0.8 microm), while compounds 2, 5 and 6 were inactive against HIV-1 PR (IC50>100 microm). This is the first report of anti-HIV-1 IN activities for wedelolactone (6), a coumarin derivative, and orobol (5), an isoflavone derivative. This study supports the use of E. prostrata in AIDS patients, which is in accord with its traditional use by Thai traditional doctors for curing blood related diseases.     

Anti-HIV-1 protease- and HIV-1 integrase activities of Thai medicinal plants known as Hua-Khao-Yen

Ethanolic- and water extracts from five species of Thai medicinal plants known as Hua-Khao-Yen were tested for their inhibitory effects against HIV-1 protease (HIV-PR) and HIV-1 integrase (HIV-1 IN). The result revealed that the ethanolic (EtOH) extract of Smilax corbularia exhibited anti-HIV-1 IN activity with an IC50 value of 1.9 microg/ml, followed by the water extract of Dioscorea birmanica (IC50 = 4.5 microg/ml), the EtOH extract of Dioscorea birmanica (IC50 = 4.7 microg/ml), the water extract of Smilax corbularia (IC50 = 5.4 microg/ml), the EtOH extract of Smilax glabra (IC50 = 6.7 microg/ml) and the water extract of Smilax glabra (IC50 = 8.5 microg/ml). The extracts of Pygmaeopremna herbacea and Dioscorea membranacea were apparently inactive (IC50 > 100 microg/ml). Interestingly, only the EtOH extract of Dioscorea membranacea showed appreciable activity (IC50 = 48 microg/ml) against HIV-1 PR, while the other extracts possessed mild activity. This result strongly supported the basis for the use of Smilax corbularia and Dioscorea membranacea for AIDS treatment by Thai traditional doctors.     

Isolation of flavonoids, a biscoumarin and an amide from the flower buds of Daphne genkwa and the evaluation of their anti-complement activity

As part of an ongoing study aimed at identifying the anti-complement active compound from the flower buds of Daphne genkwa, ten flavonoids, one biscoumarin and one amide were isolated. Their structures were identified from spectroscopic and physicochemical data as genkwanin 5-O-beta-d-primveroside (1), apigenin 7-O-beta-d-glucuronide (2), genkwanin 5-O-beta-d-glucopyranoside (3), apigenin 5-O-beta-d-glucopyranoside (4), genkwanin (5), apigenin (6), luteolin 7-methyl ether (7), luteolin (8), daphnoretin (9), velutin (10), 7-methoxyacacetin (11) and aurantiamide acetate (12). Among them, compounds 9, 10 and 12 were isolated from this plant for the first time. The anti-complement activity of these compounds was tested against the classical pathway of the complement system. Among the compounds, daphnoretin (9) exhibited significant anti-complement activity with an IC(50) value of 11.4 microm, whereas the other compounds were not active in the assay.     

Polyphenolic constituents of Actaea racemosa

A new lignan, actaealactone (1), and a new phenylpropanoid ester derivative, cimicifugic acid G (2), together with 15 known polyphenols, protocatechuic acid, protocatechualdehyde, p-coumaric acid, caffeic acid, methyl caffeate, ferulic acid, ferulate-1-methyl ester, isoferulic acid, 1-isoferuloyl-beta-d-glucopyranoside, fukinolic acid, and cimicifugic acids A, B, and D-F, were isolated from an extract of the rhizomes and roots of black cohosh (Actaea racemosa). The structures of the new compounds were determined on the basis of NMR spectroscopic analysis. Compounds 1 and 2 displayed antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free-radical assay with IC(50) values of 26 and 37 microM, respectively. Other antioxidants identified from A. racemosa include cimicifugic acid A (3), cimicifugic acid B (4), and fukinolic acid (5). Compounds 1 and 2 also exhibited a small stimulating effect on the growth of MCF-7 breast cancer cell proliferation 1.24-fold (14 microM) and 1.14-fold (10 microM), respectively, compared to untreated cells.     

Cytotoxic activity of amooranin and its derivatives

Amooranin, 25-hydroxy-3-oxoolean-12-en-28-oic acid, is a triterpene acid isolated from Amoora rohituka stem bark. The cytotoxic effects of amooranin and its derivatives were studied. Amooranin and its methyl ester showed greater cytotoxicity against MCF-7 and HeLa cells derived from tumour tissues with a 50% inhibitory concentration (IC(50)) of 1.8-3.4 microg/mL, compared with Chang liver cells from normal tissue with an IC(50) of 6.2-6.4 microg/mL, but amooranin exhibited no activity on HEp-2 and L-929 cells. However, its monoacetate derivative showed no inhibitory activity at 1-10 microg/mL dose levels. Of the cytotoxic isolates, the methyl ester derivative was inactive in in vivo evaluations in the Ehrlich ascites tumour cells at 50 and 100 mg/kg/day, demonstrating T/C values of 106% and 114%, respectively.     

Alkaloids from the leaves of Uncaria rhynchophylla and their inhibitory activity on NO production in lipopolysaccharide-activated microglia

Two new isomeric alkaloids, 18,19-dehydrocorynoxinic acid B (1) and 18,19-dehydrocorynoxinic acid (2), were isolated from the CHCl3 extract of the leaves of Uncaria rhynchophylla, together with four known rhynchophylline-type alkaloids, corynoxeine (3), isocorynoxeine (4), rhynchophylline (5), and isorhynchophylline (6), and an indole alkaloid glucoside, vincoside lactam (7). The structures of compounds 1 and 2 were elucidated by spectroscopic methods including UV, IR, HREIMS, 1D and 2D NMR, and CD experiments. The activity assay showed that compounds 3-6, with a C-16 carboxylic ester group, and 7 exhibited inhibitory activity on lipopolysaccharide (LPS)-induced NO release in primary cultured rat cortical microglia (IC 50: 13.7-19.0 microM). However, only weak inhibitory activity was observed for compounds 1 and 2, with a C-16 carboxylic acid group (IC 50: >100 microM).     

Inhibitory activities of Cassia tora and its anthraquinone constituents on angiotensin-converting enzyme

As a component of our program that pertains to the isolation of antihypertensive agents derived from natural products, we screened the bioactivity of seeds from raw and roasted Cassia tora via angiotensin converting enzyme (ACE) inhibitory assays. We found that both of the MeOH extracts from the raw and roasted C. tora exhibited significant inhibitory properties against ACE, demonstrating more than 50% inhibition at a concentration of 163.93 microg/mL. Emodin (3), alaternin (4), gluco-obtusifolin (5), cassiaside (6), gluco-aurantioobtusin (7), cassitoroside (8), toralactone gentiobioside (9), and chrysophanol triglucoside (10) had been previously isolated; however, questin (1) and 2-hydroxyemodin 1-methylether (2) were isolated from C. tora for the first time in this study. Among them, only anthraquinone glycoside (7) demonstrated marked inhibitory activity against ACE, with an IC(50) value of 30.24 +/- 0.20 microM. Conversely, aurantioobtusin (7a), obtained from the acid hydrolysis of 7, showed no activity. Further inhibitory kinetics analyzed from Lineweaver-Burk plots showed 7 to be a competitive inhibitor with a Ki value of 8.3 x 10(-5) M. Moreover, compound 7 showed marked inhibitory and scavenging activities with an IC(50) value of 49.64 +/- 0.37 microM (positive control; trolox: 26.07 +/- 1.05 microM) for total reactive oxygen species generation, and 4.60 +/- 1.12 microM (positive control; penicillamine: 0.24 +/- 0.04 microM) for ONOO(-).     

南湖菱壳中α-葡萄糖苷酶抑制活性成分研究

目的:研究南湖菱壳的化学成分及体外抑制α-葡萄糖苷酶活性。方法:对醋酸乙酯和正丁醇部位采用各种色谱法分离,运用多种波谱技术鉴定结构。结果:从南湖菱的醋酸乙酯和正丁醇部位共分离鉴定9个化合物,分别为4,23,24-三甲基胆甾-22-烯-3-醇(1),豆甾醇(2),α-香树脂醇(3),(+)-nyasol(4),齐墩果酸(5),熊果酸(6),常春藤皂苷元(7),3,23-二羟基-12-烯-28-乌苏酸(8),β-胡萝卜苷(9)。南湖菱壳总提取物、石油醚部位、醋酸乙酯部位、正丁醇部位均有体外α-葡萄糖苷酶抑制活性;化合物5(IC502.88 mg·L-1)和6(IC504.42 mg·L-1)具有体外α-葡萄糖苷酶抑制活性。结论:除化合物2外,其他化合物均为首次从该属中分离得到;化合物1～9均为首次从该植物中分离得到。     

Anti-HIV-1 limonoid: first isolation from Clausena excavata

A limonoid, clausenolide-1-ethyl ether (1) and two coumarins, dentatin (2) and nor-dentatin (3), were isolated from Clausena excavata. Limonoid 1 was obtained from the crude ethanol extract of the rhizomes and the roots but had not previously been isolated from C. excavata and exhibited HIV-1 inhibitory activity. Coumarins 2 and 3, with their structures related to an anti-HIV-1 substance, (+)-calanolide A (4), were obtained from the crude chloroform extract of the rhizomes. Both induced toxicity to cells used in a syncytium assay for anti-HIV-1 activity. These compounds, 1-3, did not show any cytotoxic effect against KB and BC-1 cell lines (IC(50) value > 20 microgram/mL).     

Sesquiterpenoids from Bombax malabaricum

Phytochemical investigation of the chemical constituents of the roots of Bombax malabaricum afforded nine cadinane sesquiterpenoids, including five new compounds (bombamalones A-D, 1-4; bombamaloside, 5), and four known compounds (isohemigossypol-1-methyl ester, 6; 2-O-methylisohemigossylic acid lactone, 7; bombaxquinone B, 8; and lacinilene C, 9). The structures of 1-5 were identified by spectroscopic methods and comparison with literature values. Compounds 1-9 were evaluated against the HGC-27 human gastrointestinal cancer cell line, but all were inactive (IC(50) >10 microM).     

番荔枝皮化学成分及其抗肿瘤活性的研究

目的:研究番荔枝Annona squamosa的化学成分,并对分离化合物进行活性筛选.方法:综合运用各种色谱方法分离纯化番荔枝中的化学成分;采用NMR等波谱方法鉴定其结构;运用SRB法测定化合物对肿瘤细胞体外增殖能力的抑制作用.结果:从番荔枝皮乙醇提取物中分离得到11个化合物,分别是annosquamosin C(1),15,16-epoxy-17-hydroxy-ent-kau-ran-19-oic acid(2),16,17-dihydroxy-ent-kauran-19-oic acid(3),annosquamosin A(4),ent-kaur-16-en-19-oic acid (5),19-nor-ent-kauran-4-ol-17-oic acid(6),16-hydroxy-ent-kau-ran-19-oic acid(7),ent-15β-hydroxy-kaur-16-en-19-oic acid (8),annosquamosin B (9),ent-16β,17-dihydroxykauran-19-al(10),16,17-dihydroxy-ent-kauran-19-oic acid methyl ester(11).抗肿瘤活性实验表明,化合物1,2,3,5,9对人肺癌95-D细胞的体外增殖能力均具有不同程度的抑制作用,化合物5的活性最强,IC50为7.78 μmol·L-1;化合物2,5,9对人卵巢癌A2780细胞有抑制作用,其中化合物2和9的抑制作用较强,IC50分别为0.89,3.10 μmol·L-1.结论:化合物2,8,11分别为首次从该科、该属和该种植物分离得到;化合物5对人肺癌95-D细胞的抑制作用较强;化合物2和9对人卵巢癌细胞A2780的抑制作用较强.     

Efficacy of scopadulcic acid A against Plasmodium falciparum in vitro

Scoparia dulcis is a perennial herb widely distributed in many tropical countries. It is used as an herbal remedy for gastrointestinal and many other ailments, and in Nicaragua extracts are used to treat malaria. Phytochemical screening has shown that scopadulcic acid A (SDA), scopadulcic acid B (SDB), and semisynthetic analogues are pharmacologically active compounds from S. dulcis. SDB has antiviral activity against Herpes simplex virus type 1, antitumor activity in various human cell lines, and direct inhibitory activity against porcine gastric H(+), K(+)-ATPase. A methyl ester of scopadulcic acid B showed the most potent inhibitory activity against gastric proton pumps of 30 compounds tested in one study. Compounds with antiviral, antifungal, and antitumor activity often show activity against Plasmodium falciparum. In P. falciparum, the plasma membrane and food vacuole have H(+)-ATPases and the acidocalcisome has an H(+)-Ppase. These proton pumps are potential targets for antimalarial therapy and may have their function disrupted by compounds known to inhibit gastric proton pumps. We tested pure SDA and found in vitro activity against P. falciparum with an IC(50) of 27 and 19 microM against the D6 and W2 clones, respectively. The IC(50) against the multidrug-resistant isolate, TM91C235, was 23 microM.     

Three new triterpenoids from Peganum nigellastrum

Three new triterpenoids, 3alpha,27-dihydroxylup-20(29)-en-28-oic acid methyl ester, 3alpha-acetoxy-27-hydroxylup-20(29)-en-28-oic acid methyl ester, and 3alpha-acetoxyolean-12-ene-27,28-dioic acid 28-methyl ester, were isolated from the roots of Peganum nigellastrum along with four known lupene-type triterpenoids. The structures of the new triterpenoids were determined by NMR spectroscopic means. The new triterpene, 3alpha, 27-dihydroxylup-20(29)-en-28-oic acid methyl ester is a DNA topoisomerase II inhibitor (IC(50) = 8.9 microM/mL).     

Neoflavonoids and related constituents from Nepalese propolis and their nitric oxide production inhibitory activity

A methanolic extract of Nepalese propolis yielded 10 new open-chain neoflavonoids (1-10), a new chalcone (11), and eight previously reported compounds (12-19). Their structures were determined on the basis of spectroscopic data and chemical conversion. The isolated compounds other than 5, 8, and 16 showed dose-dependent inhibitory activities on nitric oxide production in lipopolysaccharide-activated macrophage-like J774.1 cells and were more active than a positive control, N(G)-monomethyl-L-arginine (IC(50), 27.1 microM). The most potent activities, of 6 and 7 (IC(50), 0.5 microM), were greater than another positive control, caffeic acid phenethyl ester (IC(50), 4.8 microM).