Anti-HIV-1 protease activity of compounds from Boesenbergia pandurata

Searching for anti-HIV-1 protease (, PR) inhibitors of Thai medicinal plants led to the isolation of a new cyclohexenyl chalcone named panduratin C (1) and chalcone derivatives (2-6) from the methanol extract of Boesenbergia pandurata rhizomes. The known compounds were identified to be panduratin A (2), hydroxypanduratin A (3), helichrysetin (4), 2',4',6'-trihydroxyhydrochalcone (5), and uwvangoletin (6). The structures of all compounds were elucidated on the basis of chemical and spectroscopic methods. It was found that 3 possessed the most potent anti-HIV-1 PR activity with an IC50 value of 5.6 mu M, followed by 2 (IC50 = 18.7 mu M), whereas other compounds exhibited only mild activity. Structure-activity relationships of these Compounds on anti-HIV-1 PR activity are Summarized as follows: (1) hydroxyl moiety at position 4 conferred higher activity than methoxyl group; (2) prenylation of dihydrochalcone was essential for activity; (3) hydroxylation at position 4 reduced activity; and (4) introduction of double bond at Cl' and C6' of chalcone gave higher activity. As regards active constituents contained in B. pandurala rhizomes, hydroxypanduratin A (3) and panduratin A (2) are active principles against HIV-1 PR. (c) 2005 Elsevier Ltd. All rights reserved.