Cytotoxic Compounds from Brucea mollis

Ten compounds, including soulameanone (1), isobruceine B (2), 9-methoxy-canthin-6-one (3), bruceolline F (4), niloticine (5), octatriacontan-1-ol (6), bombiprenone (7), α-tocopherol (8), inosine (9), and apigenin 7-O-β-D-glucopyranoside (10), were isolated from the leaves, stems, and roots of Brucea mollis Wall. ex Kurz. Their structures were determined using one-and two-dimensional NMR spectroscopy and mass spectrometry. All compounds were evaluated for their cytotoxic activity against KB (human carcinoma of the mouth), LU-1 (human lung adenocarcinoma), LNCaP (human prostate adeno-carcinoma), and HL-60 (human promyelocytic leukemia) cancer cell lines. Compound 2 showed significant cytotoxic activity against KB, LU-1, LNCaP, and HL-60 cancer cells with IC₅₀ values of 0.39, 0.40, 0.34, and 0.23 μg/mL, respectively. In addition, compounds 3 and 5 showed significant cytotoxic activity against KB, LU-1, LNCaP, and HL-60 cancer cells with IC₅₀ values around 1–4 μg/mL. Compounds 9-methoxycanthin-6-one (3) and niloticine (5) have been discovered for the first time from the Brucea genus.

An evaluation of the RNase H inhibitory effects of Vietnamese medicinal plant extracts and natural compounds

CONTEXT

Acquired immune deficiency syndrome (AIDS) is a severe pandemic disease especially prevalent in poor and developing countries. Thus, developing specific, potent antiviral drugs that restrain infection by human immunodeficiency virus type 1 (HIV-1), a major cause of AIDS, remains an urgent priority.

OBJECTIVE

This study evaluated 32 extracts and 23 compounds from Vietnamese medicinal plants for their inhibitory effects against HIV-1 ribonuclease H (RNase H) and their role in reversing the cytopathic effects of HIV.

MATERIALS AND METHODS

The plants were air-dried and extracted in different solvent systems to produce plant extracts. Natural compounds were obtained as previously published. Samples were screened for RNase H inhibition followed by a cytopathic assay. Data were analyzed using the Microsoft Excel.

RESULTS AND DISCUSSION

At 50 μg/mL, 11 plant extracts and five compounds inhibited over 90% of RNase H enzymatic activity. Methanol extracts from Phyllanthus reticulatus and Aglaia aphanamixis leaves inhibited RNase H activity by 99 and 98%, respectively, whereas four extracts showed modest protection against the cytopathic effects of HIV.

CONCLUSION

The screening results demonstrated that the butanol (BuOH) extract of Celastrus orbiculata leaves, methanol (MeOH) extracts of Glycosmis stenocarpa stems, Eurya ciliata leaves, and especially P. reticulatus leaves showed potential RNase H inhibition and protection against the viral cytopathic effects of HIV-1. Further chemical investigations should be carried out to find the active components of these extracts and compounds as potential anti-HIV drug candidates.

Inhibitory effects of indirubin derivatives on the growth of HL-60 leukemia cells

Six indirubin derivatives have been synthesized and their inhibitory effects on the growth of HL-60 human promyelocytic leukemia cells investigated. Cell viability was determined using the trypan blue exclusion method. Indirubin-3'-oxime (I-1) inhibited the growth of HL-60 cells with a GI50 value of 36.6 microM, whereas I-0, I-2, I-3, I-4 and I-6 showed only weak cytotoxic activities against HL-60 cancer cells with GI50 values in the range of 97.3 to over 100 microM. These results indicate that indirubin derivatives might be useful candidate agents for exploring potential antileukemic drugs.

Inhibitory Effects of Indirubin Derivatives on the Growth of HL-60 Leukemia Cells

Six indirubin derivatives have been synthesized and their inhibitory effects on the growth of HL-60 human promyelocytic leukemia cells investigated. Cell viability was determined using the trypan blue exclusion method. Indirubin-3′-oxime (I-1) inhibited the growth of HL-60 cells with a GI50 value of 36.6 μM, whereas I-0, I-2, I-3, I-4 and I-6 showed only weak cytotoxic activities against HL-60 cancer cells with GI50 values in the range of 97.3 to over 100 μM. These results indicate that indirubin derivatives might be useful candidate agents for exploring potential antileukemic drugs.

Murrayafoline A attenuates the Wnt/beta-catenin pathway by promoting the degradation of intracellular beta-catenin proteins

Molecular lesions in Wnt/beta-catenin signaling and subsequent up-regulation of beta-catenin response transcription (CRT) occur frequently during the development of colon cancer. To identify small molecules that suppress CRT, we screened natural compounds in a cell-based assay for detection of TOPFalsh reporter activity. Murrayafoline A, a carbazole alkaloid isolated from Glycosmis stenocarpa, antagonized CRT that was stimulated by Wnt3a-conditioned medium (Wnt3a-CM) or LiCl, an inhibitor of glycogen synthase kinase-3beta (GSK-3beta), and promoted the degradation of intracellular beta-catenin without altering its N-terminal phosphorylation at the Ser33/37 residues, marking it for proteasomal degradation, or the expression of Siah-1, an E3 ubiquitin ligase. Murrayafoline A repressed the expression of cyclin D1 and c-myc, which is known beta-catenin/T cell factor (TCF)-dependent genes and thus inhibited the proliferation of various colon cancer cells. These findings indicate that murrayafoline A may be a potential chemotherapeutic agent for use in the treatment of colon cancer.

Chrysoeriol isolated from the leaves of Eurya ciliata stimulates proliferation and differentiation of osteoblastic MC3T3-E1 cells

Chrysoeriol (1) was isolated as the main constituent from the methanol extract of the dried leaves of Eurya ciliata Merr. To investigate the bioactivities of 1 on bone metabolism, its effects on the function of osteoblastic MC3T3-E1 cells were studied. Compound 1 significantly increased the growth of MC3T3-E1 cells and caused a significant elevation of alkaline phosphatase activity, collagen content, and nodule mineralization in the cells (P < 0.05). Our data indicate that the enhancement of osteoblast function by 1 may be useful in the prevention of osteoporosis.

First Synthesis of Dimethyl-1H-Isochromeno[3,4-b]Carbazoles

The first synthesis of isochromene fused carbazols, (4a S, 13b R)-2,5,5-trimethyl-3,4,4a,5,8,13b-hexahydroisochromeno[3,4-b]carbazole (2) and its epi-isomer 3 by condensation of citral and 2-hydroxycarbazole using Ti(OEt)4 and MeAlCl2 as catalysts is described.

First synthesis of dimethyl-1H-isochromeno[3,4-b]carbazoles

The first synthesis of isochromene fused carbazols, (4aS, 13bR)-2,5,5-trimethyl-3,4,4a,5,8,13b-hexahydroisochromeno[3,4-b]carbazole (2) and its epi-isomer 3 by condensation of citral and 2-hydroxycarbazole using Ti(OEt)4 and MeAlC12 as catalysts is described.

1-O-Substituted derivatives of murrayafoline A and their antifungal properties

The synthesis of some 1-oxygenated derivatives of murrayafoline A (1) and their antifungal properties is reported. Three derivatives, 1-hydroxy-3-methyl-9H-carbazole (2), 1-(3-methylbut-2-enyloxy)-3-methyl-9H-carbazole (3) and 1-(2,3,4,6-tetra-O-acetyl-alpha-D-O-glucopyranosyl)-3-methyl-9H-carbazole (4) of murrayafoline A were synthesized. Compounds 1 and 2 exhibited strong fungicidal activity against Cladosporium cucumerinum at the dose of 12.5 microg.

"Studies on biodiversity of Vietnam and Laos" 1998-2005: examining the impact

The impact of the University of Illinois at Chicago-based Vietnam-Laos International Cooperative Biodiversity Group (ICBG) Program "Studies on Biodiversity of Vietnam and Laos", which has been in operation for the period of 1998-2005, touches on five major areas of endeavor: (a) biodiversity inventory and conservation; (b) studies on medicinal plants; (c) drug discovery and development; (d) economic development; and (e) issues on intellectual property rights and benefit sharing in natural products drug discovery and development. Highlights are presented and the significance is discussed.

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.

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.

Ethnobotany/ethnopharmacology and mass bioprospecting: issues on intellectual property and benefit-sharing

Ethnobotany/ethnopharmacology has contributed to the discovery of many important plant-derived drugs. Field explorations to seek and document indigenous/traditional medical knowledge (IMK/TMK), and/or the biodiversity with which the IMK/TMK is attached, and its conversion into a commercialized product is known as bioprospecting or biodiversity prospecting. When performed in a large-scale operation, the effort is referred to as mass bioprospecting. Experiences from the mass bioprospecting efforts undertaken by the United States National Cancer Institute, the National Cooperative Drug Discovery Groups (NCDDG) and the International Cooperative Biodiversity Groups (ICBG) programs demonstrate that mass bioprospecting is a complex process, involving expertise from diverse areas of human endeavors, but central to it is the Memorandum of Agreement (MOA) that recognizes issues on genetic access, prior informed consent, intellectual property and the sharing of benefits that may arise as a result of the effort. Future mass bioprospecting endeavors must take heed of the lessons learned from past and present experiences in the planning for a successful mass bioprospecting venture.

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.

A new ent-kaurane diterpenoid from Croton tonkinensis leaves

A new ent-kaurane diterpenoid (1) was isolated from the leaves of Croton tonkinensis. The structure of 1 was determined as ent-7beta-hydroxy-15-oxokaur-16-en-18-ol from spectroscopic methods.