Further sesquiterpenes from Polygonum viscosum (Polygonaceae)

Swarnalin andcis-swarnalin, two new tetrahydrofuran derivatives with free radical scavenging activity, from the aerial parts ofCuscuta reflexa

The reversed-phase HPLC analysis of a methanol extract of the aerial parts of Cuscuta reflexa afforded a non-separable mixture (55 : 45) of two novel tetrahydrofuran derivatives, named swarnalin (1) and cis-swarnalin (2), and a known coumarin, 5,6,7-trimethoxycoumarin (3). The structures of the compounds were elucidated unequivocally by UV, HRFABMS and a series of 1D and 2D NMR analyses. The mixture of 1 and 2 showed significant free radical scavenging activity in the DPPH assay and the RC50 value was found to be 3.80 x 10(-4) mg mL(-1) for the mixture, compared to 2.88 x 10(-5) mg mL(-1) for the positive control, quercetin.

Gedunin, a limonoid from Xylocarpus granatum, inhibits the growth of CaCo-2 colon cancer cell line In Vitro

Xylocarpus granatum J. König (Meliaceae), commonly known as 'dhundul', is a Bangladeshi mangrove tree, and well distributed in a number of other countries of south-east Asia, Australia and east Africa. Traditionally, X. granatum has been used as an astringent and febrifuge, and also for the treatment of fever, malaria, thrush, cholera, dysentery and diarrhoea in many countries including Bangladesh. Two limonoids, gedunin and 1alpha-hydroxy-1,2-dihydrogedunin, the latter being new, have been isolated from the bark of Xylocarpus granatum by reversed-phase preparative HPLC, and the structures were confirmed by spectroscopic means. The cytotoxic potential of gedunin has been evaluated by the Promega's CellTiter 96 non-radioactive cell proliferation assay using the CaCo-2 colon cancer cell line (IC(50) = 16.83 microM). A summary of the biological activities of gedunin reported to date is also presented.

Isolation and structure of ruprechstyril from Ruprechtia tangarana

Bioassay (P388 lymphocytic leukemia cell line and human cancer cell lines)-guided separation of an extract prepared from the stem bark and twigs of the previously uninvestigated Ruprechtia tangarana led to the isolation of a new isocarbostyril designated ruprechstyril (1), secalonic acid A (2), 2'-O-methylevernic acid (3), 3,3',4-tri-O-methylflavellagic acid (4), lichexanthone (5), methyl asterrate (6), and 3beta,22E,24S-stigmasta-5,22-dien-3-ol (7). Only secalonic acid A exhibited cancer cell and microbial growth inhibition. The structure of ruprechstyril (1) was determined by HRMS and 1D and 2D NMR spectra and confirmed by single-crystal X-ray analysis. The structures and absolute stereochemistry of five of the other compounds were also established by X-ray crystal structure determination.