Glutathione S-transferase, acetylcholinesterase inhibitory and antibacterial activities of chemical constituents of Barleria prionitis

Phytochemical studies on the ethanolic extract of Barleria prionitis of Sri Lankan origin have resulted in the isolation of a new compound, balarenone (1), along with three known compounds, pipataline (2), lupeol (3) and 13,14-seco-stigmasta-5,14-diene-3-α-ol (4). The structures of 1-4 were elucidated with the aid of extensive NMR spectroscopic studies. Compounds 1-4 showed moderate inhibitory activity against glutathione S-transferase (GST) and acetylcholinesterase (AChE). Compounds 1, 2 and 4 also exhibited antibacterial activity against Bacillus cereus and Pseudomonas aeruginosa (25 μg/disk). Three different derivatives of compound (2), 7,8-epoxypipataline (5), 8-amino-7-hydroxypipataline (6) and 7,8-dibromopipataline (7) were synthesized to evaluate them for GST and AChE inhibitory activities. Household microwave radiations were used to synthesize compound (6). Among all tested compounds, 8-amino-7-hydroxypipataline (6) exhibited a significant AChE inhibitory activity with an IC50 value of 36.8 μM. © 2007 Verlag der Zeitschrift für Naturforschung.