Bioactive compounds from Vitex leptobotrys.

A new lignan, vitexkarinol (1), as well as a known lignan, neopaulownin (2), a known chalcone, 3-(4-hydroxyphenyl)-1-(2,4,6-trimethoxyphenyl)-2-propen-1-one (3), two known dehydroflavones, tsugafolin (4) and alpinetin (5), two known dipeptides, aurantiamide and aurantiamide acetate, a known sesquiterpene, vemopolyanthofuran, and five known carotenoid metabolites, vomifoliol, dihydrovomifoliol, dehydrovomifoliol, loliolide, and isololiolide, were isolated from the leaves and twigs of Vitex leptobotrys through bioassay-guided fractionation. The chalcone (3) was found to inhibit HIV-1 replication by 77% at 15.9 µM, and the two dehydroflavones (4 and 5) showed weak anti-HIV activity with IC50 values of 118 and 130 µM, respectively, while being devoid of cytotoxicity at 150 µM. A chlorophyll-enriched fraction of V. leptobotrys, containing pheophorbide a, was found to inhibit the replication of HIV-1 by 80% at a concentration of 10 µg/mL. Compounds 1 and 3 were further selected to be evaluated against 21 viral targets available at NIAID (National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA).

Study of antimalarial activity of chemical constituents from Diospyros quaesita.

Bioassay-directed fractionation led to the isolation of seven compounds from a sample of the dried leaves, twigs, and branches of Diospyros quaesita Thw. (Ebenaceae). One of the isolates, betulinic acid 3-caffeate (1), showed in vitro antimalarial activity against Plasmodium falciparum clones D(6) (chloroquine-sensitive) and W(2) (chloroquine-resistant) with IC(50) values of 1.40 and 0.98 microM, respectively. Evaluation of compound 1 in the human oral epidermoid (KB) cancer cell line revealed cytotoxicity at ED(50) of 4.0 microM. In an attempt to reduce the cytotoxicity of 1, the acetylated derivative 1a and betulinic acid (1b) were prepared. Of the seven isolates, diospyrosin (2) was determined to be a new neolignan. In addition to 1, other known compounds isolated in this study were pinoresinol, lariciresinol, N-benzoyl-L-phenylalaninol, scopoletin, and poriferast-5-en-3beta,7alpha-diol. The structure of 2 was elucidated based on spectroscopic data analysis including 1D- and 2D-NMR, and HR-ESI-MS.

Rourinoside and rouremin, antimalarial constituents from Rourea minor.

Bioassay-directed fractionation of the antimalarial active CHCl(3) extract of the dried stems of Rourea minor (Gaertn.) Aubl. (Connaraceae) liana led to isolation of two glycosides, rourinoside (1) and rouremin (2), as well as five known compounds, 1-(26-hydroxyhexacosanoyl)-glycerol (3), 1-O-beta-D-glucopyranosyl-(2S,3R,4E-8Z)-2-N-(2'-hydroxypalmitoyl)-octadecasphinga-4,8-dienine, 9S,12S,13S-trihydroxy-10E-octadecenoic acid, dihydrovomifoliol-9-beta-D-glucopyranoside, and beta-sitosterol glucoside. Compounds 1-3 showed weak in vitro activities against Plasmodium falciparum. Their structures and stereochemistry were elucidated by spectroscopic methods and selected enzyme hydrolysis.

Antimalarial compounds from Grewia bilamellata.

Bioassay-directed fractionation led to the isolation of 12 compounds from a sample of the dried leaves, twigs, and stems of Grewia bilamellata. Five of the isolates, 3alpha,20-lupandiol (1), grewin (2), nitidanin (4), 2alpha,3beta-dihydroxy-olean-12-en-28-oic acid (5), and 2,6-dimethoxy-1-acetonylquinol (6), showed varying degrees of in vitro antimalarial activity against Plasmodium falciparum, but were devoid of significant cytotoxicity to the human oral epidermoid KB cancer cell line. Of the 12 isolates, compounds 1, 2, and 3 (bilagrewin) were determined to be a new triterpene, a new coumarinolignan, and a new neolignan, respectively. Other known compounds isolated in this study were 8-O-4' neolignan guaiacylglycerol-beta-coniferyl ether isomers (threo and erythro), cleomiscosin D, icariol A(2), ciwujiatone, and daucosterol. The structures of 1-3 were elucidated and identified on the basis of spectroscopic data including 1D and 2D NMR analysis.

Miliusanes, a class of cytotoxic agents from Miliusa sinensis.

Bioassay-directed fractionation of the leaves, twigs, and flowers of Miliusa sinensis Finet and Gagnep. (Annonaceae) led to the isolation of a new class of potential anticancer lead molecules. They are a cluster of compounds composed of a C(18) carbon skeleton, a known but heretofore unnamed type, which we have designated as miliusane. Two known (1 and 2) as well as 20 new miliusanes (3-22) have been isolated and identified. They belong to two substructural classes of miliusanes. One subclass (1-19) was determined to be composed of a gamma-lactone spiro-ring system, the opening of which led to the second group of compounds (21 and 22) containing a tetrahydrofuran ring system. Compounds 1-3, 5, 8, 9, 18, 20, and 21 demonstrated significant cytotoxic activity in our cancer cell line panel comprising KB, Col-2, LNCaP, Lu-1, MCF-7, and HUVEC. The structures were determined by spectroscopic and chemical methods. The structure of miliusate was further confirmed by X-ray crystallographic analysis. The absolute stereochemistry of miliusanes was established by the Mosher ester method. Forty-two modified miliusane derivatives were also prepared and evaluated for their cytotoxic activities.

Bioactive constituents from roots of Bursera tonkinensis.

Bioassay directed-fractionation led to isolation of 12 compounds from the roots of Bursera tonkinensis Guillaum (Burseraceae), including burselignan, bursephenylpropane, and burseneolignan. Of the 12 compounds, only 4'-demethyldesoxypodophyllotoxin exhibited significant cytotoxic activities against KB, Col2 and LNCaP cell lines.

Sesquiterpenes and butenolides, natural anti-HIV constituents from Litsea verticillata.

In a continuing investigation, six sesquiterpenes, as well as five butenolides were isolated from the leaves and twigs of Litsea verticillata Hance (Lauraceae). Among the isolates, three were determined to be new sesquiterpenes: isolitseanes A (1), B (2) and C (3); three known sesquiterpenes were identified as oxyphyllenodiol B (4), 1,2,3,4-tetrahydro-2,5-dimethyl-8-(1-methylethyl)-1,2-naphthalenediol (5), and chromolaevanedione (6). The butenolides include the novel litseabutenolide (9) and four known compounds: 3- epi-litsenolide D2 (7), cis-listenolide D1 (8), 4-hydroxy-2-methylbut-2-enolide (10), and hydroxydihydrobovolide (11). Isolates 2, 4, 5, 7, 9, 10 and 11 were found to inhibit HIV-1 replication in a green fluorescent protein (GFP)-based reporter cell line (HOG.R5) with IC50 values of 38.1, 54.6, 91.0, 9.9, 40.3, 129.8, and 122.7 microM, respectively. Structure elucidation and identification were based on spectroscopic means including 1D and 2D NMR analyses.

Anti-tuberculosis constituents from the stem bark of Micromelum hirsutum.

Anti-TB bioassay-directed fractionation led to the isolation of six carbazole alkaloids, as well as the gamma-lactone derivative of oleic acid, from the CH (2)Cl (2) extract of the stem bark of Micromelum hirsutum. The carbazoles include the new micromeline ( 2) and five known alkaloids: lansine ( 3), 3-methylcarbazole ( 4), methyl carbazole-3-carboxylate ( 5), 3-formylcarbazole ( 6), and 3-formyl-6-methoxycarbazole ( 7). Compound 1 was identified as the lactone derivative of oleic acid, (-)- Z-9-octadecene-4-olide, for which the trivial name micromolide ( 1) is suggested. It showed potent in vitro anti-TB activity against H37R v (MIC: 1.5 microg/mL), a selectivity index (SI) of 63, and exhibited activity against the Erdman strain of M. tuberculosis in a J774 mouse macrophage model (EC (90) : 5.6 microg/mL). Thus, 1 appears worthy of further evaluation as a potential new anti-TB agent. Isolates 2, 3, 6 and 7 had anti-TB MIC values between 14.3 and 42.3 microg/mL, while compounds 4 and 5 were considered inactive (MIC > 128 microg/mL). Structure elucidation and identification were based on spectroscopic analysis, including MS, 1D/2D NMR, and a full (1)H spin system analysis of 1.

Antimalarial constituents from Nauclea orientalis (L.) L.

Bioassay-guided fractionation of the antimalarial-active CHCl3 extract of the dried stem of Nauclea orientalis (L.) L. (Rubiaceae) has resulted in the isolation of two novel tetrahydro-beta-carboline monoterpene alkaloid glucosides, naucleaorine (= (16alpha,17beta)-3,14:15,20-tetradehydro-16-ethenyl-17-(beta-D-glucopyranosyloxy)-19alpha-methoxyoxayohimban-21-one; 1) and epimethoxynaucleaorine (2), as well as the known compounds, strictosidine lactam (= (15beta,16alpha,17beta)-19,20-didehydro-16-ethenyl-17-(beta-D-glucopyranosyloxy)oxayohimban-21-one; 3), 3,4,5-trimethoxyphenol (4), 3alpha-hydroxyurs-12-en-28-oic acid methyl ester (5), 3alpha,23-dihydroxyurs-12-en-28-oic acid (6), 3alpha,19alpha,23-trihydroxyurs-12-en-28-oic acid methyl ester (7), and oleanolic acid (8). Compounds 1, 2, 6, and 8 showed moderate in vitro activities against Plasmodium falciparum. Their structures and configurations were elucidated by spectroscopic methods including 1D- and 2D-NMR analyses.

Bioactive constituents from Asparagus cochinchinensis.

Bioassay-directed fractionation of the dried roots of Asparagus cochinchinensis led to the isolation of a new spirostanol saponin, asparacoside (1), two new C-27 spirosteroids, asparacosins A (2) and B (3), a new acetylenic derivative, 3' '-methoxyasparenydiol (4), and a new polyphenol, 3'-hydroxy-4'-methoxy-4'-dehydroxynyasol (6), as well as five known phenolic compounds, asparenydiol (5), nyasol (7), 3' '-methoxynyasol (8), 1,3-bis-di-p-hydroxyphenyl-4-penten-1-one (9), and trans-coniferyl alcohol (10). Compounds 1, 6, and 8 demonstrated moderate cytotoxicities in a panel comprised of KB, Col-2, LNCaP, Lu-1, and HUVEC cells, with IC(50) values ranging from 4 to 12 microg/mL. The structures were determined by spectroscopic and chemical methods.

New Sesquiterpenes from Litsea verticillata.

Seven new sesquiterpenes, named litseagermacrane (1), 7-epi-eudesm-4(15)-ene-1alpha,6alpha-diol (2), 5-epi-eudesm-4(15)-ene-1beta,6beta-diol (4), litseahumulanes A (6) and B (7), and litseachromolaevanes A (11) and B (12), as well as the known compounds 7-epi-eudesm-4(15)-ene-1beta,6beta-diol (3), eudesm-4(15)-ene-1beta,6alpha-diol (5), octahydro-4-hydroxy-3alpha-methyl-7-methylene-alpha-(1-methylethyl)-1H-indene-1-methanol (8), 10-hydroxyl-15-oxo-alpha-cadinol (9), and aphanamol II (10), were isolated from an anti-HIV fraction of the leaves and twigs of Litsea verticillata Hance (Figure 1). Isolates 1, 4, and 12 were found to inhibit HIV-1 replication in a green fluorescent protein (GFP)-based reporter cell line (HOG.R5) with IC(50) values of 6.5 (27.5), 17.4 (73.1), and 28.0 (119.7) microg/mL (microM), respectively. The structures of these isolates were determined by spectral data including 1D and 2D NMR spectra. Compound 11 was confirmed by X-ray crystallographic analysis.

Natural anti-HIV agents. Part IV. Anti-HIV constituents from Vatica cinerea.

In a continuing search for anti-HIV compounds from plants of Vietnam, 19 compounds, including a new triterpene, were isolated from an extract of the leaves and stem of Vatica cinerea. The new triterpene was determined to be a cycloartane triterpenoid with 29 skeletal carbons and was assigned the name vaticinone (1). The known triterpenes included three cycloartanes, a lanostane, two dammaranes, three lupanes, an ursane, and an oleanane. A chlorophyll isolate was identified as pheophorbide a (13). The majority of the triterpenes, the sesquiterpene, 1-hydroxycyclocolorenone, and pheophorbide a showed anti-HIV activity, with the chlorophyll being the most active, demonstrating an IC(50) value of 1.5 microgram/mL (2.5 microM), while being completely devoid of toxicity up to a concentration of 20 microgram/mL (33.8 microM). Vaticinone (1) was found to inhibit the replication of HIV-1, with an IC(50) value of 6.5 microgram/mL (15.3 microM; selective index = 1.4). The structures of these isolates were determined by spectral data including 1D and 2D NMR spectra.

Antimalarial agents from plants. III. Trichothecenes from Ficus fistulosa and Rhaphidophora decursiva.

Bioassay-directed fractionation of an extract prepared from the dried leaves and stem barks of Ficus fistulosa Reinw. ex Blume (Moraceae) led to the isolation of verrucarin L acetate (1), together with 3alpha-hydroxyisohop-22(29)-en-24-oic acid, 3beta-gluco-sitosterol, 3,4-dihydro-6,7-dimethoxyisocarbostyril, 3,4,5-trimethoxybenzyl alcohol, alpha-methyl-3,4,5-trimethoxybenzyl alcohol, indole-3-carboxaldehyde, palmanine, and aurantiamide acetate. Roridin E (2) was identified in a subfraction from the dried leaves and stems of Rhaphidophora decursiva Schott (Araceae). Verrucarin L acetate and roridin E were characterized as macrocyclic trichothecene sesquiterpenoids and found to inhibit the growth of Plasmodium falciparum with IC 50 values below 1 ng/ml.

Natural anti-HIV agents-part I: (+)-demethoxyepiexcelsin and verticillatol from Litsea verticillata.

The eudesmane sesquiterpenoid, verticillatol (1), as well as the lignan, (+)-5'-demethoxyepiexcelsin (2), and a known lignan, (+)-epiexcelsin (3), were isolated from Litsea verticillata Hance. Lignan 2 showed moderate anti-HIV activity with an IC(50) value of 16.4 microg/ml (42.7 microM), while the known lignan 3 was inactive up to a concentration of 20 microg/ml (48.3 microM). Compound 1 demonstrated weak activity with an IC(50) value of 34.5 microg/ml (144.7 microM) while being devoid of cytotoxicity at 20 microg/ml. The structures were elucidated by 1D and 2D NMR spectroscopy, and the absolute configuration of the new sesquiterpenoid was determined by the generation of Mosher esters.