A new complex iridoid, prismatomerin (1), has been isolated from the leaves of Prismatomeris tetrandra, together with the known glucoside gaertneroside (4). The structures of 1 and 4 were determined by spectroscopic analysis, notably 2D NMR techniques. The (1R,5S,8S,9S,10S)-(-) absolute configuration of prismatomerin (1) was determined by comparison of the vibrational circular dichroism (VCD) spectrum calculated using density functional theory and the experimental VCD spectrum of the O-acetyl derivative 3. Prismatomerin (1) showed remarkable antitumor activity and also interfered with mitotic spindle formation.

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A series of cis-platinum ethynyl complexes with the general formula cis-[Pt(dppe)(C[triple bond]CR)2](dppe = 1,2-bis(diphenylphosphino)ethane; R = C6H4-p-NO2 1, C6H4-p-CH3 2, C6H4-p-C[triple bond]CH 3 and C6H4-p-C6H4-p-C[triple bond]CH 4) have been prepared by the coupling reaction of cis-[Pt(dppe)Cl2] with two equivalents of the appropriate alkyne. The new complexes have been fully characterized by spectroscopic techniques, and the cis square planar arrangement at the platinum centre has been confirmed by single-crystal X-ray diffraction studies of complexes 1, 2 and 4. The absorption spectra of the complexes 1-4 are dominated by a pi-->pi* band that contains some platinum (n + 1) p orbital character. The position of the band is dependent on the electron donating or withdrawing properties of the ethynyl substituents, R. Complex 1 displays a triplet emission in the green, at room temperature, while complexes 2-4, display singlet emissions in the blue. Again, the difference can be attributed to the nature of the R substituents.

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Bioassay-guided investigation of the stems of Cornus kousa led to the isolation of 12 compounds such as four triterpenoids: betulinic acid (1), maslinic acid (2), arjunolic acid (3), 3-isoarjunolic acid (4), four flavanoids; catechin (5), epi-catechin (6), 2-hydroxynaringenin (7), 2-hydroxynaringenin-7-O-beta-D-glucopyranoside (8), two ellagic acid derivatives; 3,4,3'-tri-O-methylellagic acid (9), 3,4-di-O-methylellagic acid (10), a daucosterol (11) and a sucrose derivative; (3'-O-p-coumaroyl)-beta-D-fructofuranosy-(2?1)-(6-O-p-coumaroyl)-alpha-D-glucopyranoside (12). Their structures were elucidated on the basis of spectroscopic studies as well as by comparison with available data in the literature. The free radical scavenging activity and elastase inhibition activity were investigated for the development of antiaging ingredients as a raw material for use in cosmetics. Among these compounds, compounds 1, 2 and 8 showed significant elastase inhibition activity and IC(50) was 10.81 microg/mL, 21.21 microg/mL and 44.63 microg/mL, respectively, on porcine pancreatic elastase, whereas compounds 5, 6, 7 and 8 showed significant free radical scavenging activity and SC(50) was 8.37 microg/mL, 9.31 microg/mL, 9.23 microg/mL and 17.45 microg/mL, respectively.

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Quercetin-3-O-beta-D-glucopyranoside was isolated from the ethylacetate soluble fraction of the ethanol extract of the fresh leaves of Azadirachta indica (Family: Meliaceae). The crude extract of hexane, ethylacetate and butanol soluble fractions of this ethanol extract were subjected to antimicrobial screening and brine shrimp lethality bioassay. The ethylacetate crude extract exhibited moderate antimicrobial activity against most of the test organisms and also showed significant cytotoxicity having LC50 0.61 µg/ml.DOI: http://dx.doi.org/10.3329/dujs.v60i1.10328Dhaka Univ. J. Sci. 60(1): 11-14, 2012 (January)