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The bioassay-directed fractionation of the roots of Radermachera boniana Dop. (Bignoniaceae) led to the isolation of 17 naphthalene-based quinones and related derivatives including the new radermacherones A (1), B (2) and C (6), radermaquinone (3), and radermacherol (5). The absolute configuration of 2 was determined through X-ray crystallographic analysis. The isolates 3, hydroxy-β-isonaphthoquinone (4), 6, α-naphthoquinone (8), β-naphthoquinone (9), 3-hydroxy-β-naphthoquinone (10), 4-oxo-β-naphthoquinone (11), 2-acetyl-naphtha[2,3-b]furan-4,9-dione (BBI608) (12), 2-acetyl-7-methoxy-naphtho[2,3-b]furan-4,9-dione(13), stenocarpoquin-one B (14), dehydro-α-isonaphthoquinone (15) and 3-hydroxydehydro-α-isonaphthoquinone (16) showed cytotoxic activity in a cancer cell line panel comprising KB, Col-2, Lu-1 and MCF-7 with IC50 values ranging from 0.15-38.6 µM. Compounds 12 (known as BBI608) and its methoxy derivative, 13 with extended conjugation showed the highest cytotoxicity among the tested compounds with IC50 values ranging from 0.12-3.33 µM, but 13 showed much different cancer cell killing selectivity than 12.

The bioassay-directed fractionation of the roots of Radermachera boniana Dop. (Bignoniaceae) led to the isolation of 17 naphthalene-based quinones and related derivatives including the new radermacherones A (1), B (2) and C (6), radermaquinone (3), and radermacherol (5). The absolute configuration of 2 was determined through X-ray crystallographic analysis. The isolates 3, hydroxy-β-isonaphthoquinone (4), 6, α-naphthoquinone (8), β-naphthoquinone (9), 3-hydroxy-β-naphthoquinone (10), 4-oxo-β-naphthoquinone (11), 2-acetyl-naphtha[2,3-b]furan-4,9-dione (BBI608) (12), 2-acetyl-7-methoxy-naphtho[2,3-b]furan-4,9-dione(13), stenocarpoquin-one B (14), dehydro-α-isonaphthoquinone (15) and 3-hydroxydehydro-α-isonaphthoquinone (16) showed cytotoxic activity in a cancer cell line panel comprising KB, Col-2, Lu-1 and MCF-7 with IC50 values ranging from 0.15-38.6 µM. Compounds 12 (known as BBI608) and its methoxy derivative, 13 with extended conjugation showed the highest cytotoxicity among the tested compounds with IC50 values ranging from 0.12-3.33 µM, but 13 showed much different cancer cell killing selectivity than 12.

A new plant species, Barringtonia maunwongyathiae. W. Chuakul (Lecythidaceae), was recently discovered in Khuan Thon Forest, Ao Luek District, Krabi Province, Thailand. Chemical investigation of th...

As a result of bioassay-guided fractionation, betulinic acid, a pentacyclic triterpene, was identified as a melanoma-specific cytotoxic agent. In follow-up studies conducted with athymic mice carrying human melanomas, tumour growth was completely inhibited without toxicity. As judged by a variety of cellular responses, antitumour activity was mediated by the induction of apoptosis. Betulinic acid is inexpensive and available in abundant supply from common natural sources, notably the bark of white birch trees. The compound is currently undergoing preclinical development for the treatment or prevention of malignant melanoma.

From the medicinal plant Isodon rubescens, we isolated two novel diterpenes, rubesanolides A (1) and B (2). The compounds contain a unique β-lactone subgroup. This is the first discovery for a natural diterpene having rings A, B, and C in chair, boat, and twist-chair conformations, respectively. The structures were elucidated by analysis of spectroscopic data, and the absolute configuration of 1 was determined by X-ray diffraction.

Three new dammarane triterpenes, bruguierins A-C (1-3), were isolated from a petroleum ether extract of the flowers of Bruguiera gymnorrhiza. Their structures were determined on the basis of physical and spectroscopic data interpretation. With stably transfected HepG2 cells, the three isolates activated antioxidant response element (ARE luciferase activation) with EC(50) values of 7.8, 9.4, and 15.7 microM, respectively. Bruguierin A (1) also inhibited phorbol ester-induced NFkappaB (nuclear factor-kappaB) luciferase activation with an IC(50) value of 1.4 microM and selectively inhibited cyclooxygenase-2 (COX-2) activity with an IC(50) value of 0.37 microM. Compounds 2 and 3 were not active in these bioassays.

Crataegus monogyna Jacq (Lindm), C. laevigata (Poir) DC, or related Crataegus species, collectively known as hawthorn, have been used in the treatment of cardiovascular diseases. Clinical studies have found that standardized extracts show promise as adjunctive agents for the treatment of left ventricular dysfunction. Other trials consistently demonstrate its ability to improve exercise tolerance and symptoms of mild to moderate heart failure. Preliminary evidence indicates that it improves left ventricular performance, as measured by ejection fraction. In order to properly use hawthorn in the treatment of heart failure, a large, controlled, multicenter trial in which mortality serves as the primary endpoint is needed.

A continuing study of Catharantbus lanceus for antineoplastic alkaloids has resulted in the isolation of vindolinine (as HC1), which is reported for the first time from this plant. Perivine and yohimbine, reported previously, were also obtained in high yield.