Hydnocarpus wightiana is advocated in traditional Indian medicine to possess strong antidiabetic activity. In the course of identifying bioactive fractions from Indian medicinal plants we observed that acetone extract of the seed hulls of H. wightiana possess strong free radicals (DPPH and ABTS) scavenging, alpha-glucosidase and moderate N-acetyl-beta-D-glucosaminidase inhibitory activities. Further fractionation of the extract led to the isolation of hydnocarpin, luteolin and isohydnocarpin in substantial yields. All the compounds showed strong ABTS scavenging property. However, only luteolin could display strong DPPH scavenging activity. Furthermore, all the three compounds also showed varying degrees of alpha-glucosidase and N-acetyl-beta-D-glucosaminidase inhibitory activity, luteolin being the superior. The kinetics of alpha-glucosidase inhibition by these compounds showed that acetone extract inhibits the enzyme in competitive manner however, luteolin and isohydnocarpin showed mixed-type inhibition. This is the first report assigning hydnocarpin and isohydnocarpin free radical scavenging, alpha-glucosidase and N-acetyl-beta-D-glucosaminidase inhibitory properties and luteolin as N-acetyl-beta-D-glucosaminidase inhibitor. This study suggests that presence of amphiphilic antioxidant molecules along with enzyme inhibitory activities in the acetone extract of H. wightiana seed hulls may be responsible for the antidiabetic properties as advocated in traditional medicine.

Bioassay-guided fractionation of different extracts of both stem and stem bark of Stereospermum personatum led to the isolation of free-radical-scavenging and xanthine oxidase inhibitory molecules along with three new anthraquinones, sterequinones F-H (1-3), a new naphthoquinone, sterequinone I (4), two new phenethyl esters, 2(4'-hydroxyphenyl)ethyl undecanoate (14) and 2(4'-hydroxyphenyl)ethyl nonacosanoate (15), and a new 3,4,5-trimethoxycinnamyl ether, 2-methoxy-4-[3'-(3'',4'',5''trimethoxyphenyl)allyloxymethyl]phenol (16), together with known compounds. The antioxidant and xanthine oxidase inhibitory potentials of the isolated compounds are reported.

Enzyme Inhibitors: Synthesis, Biological Evaluation and Structure-Activity Relationship. -The title compounds show significantly enhanced a-glucosidase and xanthine oxidase inhibition. -(RAO, R. J.; TIWARI, A. K.; KUMAR, U. S.; REDDY, S. V.; ALI, A. Z.; RAO*, J. M.; Bioorg. Med.

A new germacrane derivative, care none (1) was isolated from the stems of a well-known medicinal plant, Carissa spinarum L. together with a new ester, 3'-(4''-methoxyphenyl)-3-oxo-ropionyl hexadecanoate (2). Their structures were established using 1D, 2D NMR spectroscopic and synthetic methods. The chloroform extract of the plant displayed strong antioxidant (DPPH) activity. Several other known compounds were also isolated for the first time from this active extract. The antioxidant activity of major lignans was studied.

The synthesis of the macrolactone core of (+)-neopeltolide has been achieved. The key synthetic strategy involves the highly diastereoselective synthesis of the 2,6-cis-disubstituted tetrahydropyran ring by a transannular cyclization of δ-hydroxy alkene using mercuric trifluoroacetate. Two of the six stereocenters C-5 and C-11 were realized from L-malic acid, while the remaining stereocenters C-3 (Sharpless asymmetric epoxidation), C-7 (transannular cyclization), C-9 (regioselective epoxide opening) and C-13 (chelation controlled reduction) were derived by asymmetric synthesis. The macrolactone ring was synthesized by macrocyclization using a RCM protocol.