Cytotoxic 6-Substituted 5,6-Dihydro-2H-pyran-2-ones from a Brazilian Medicinal Plant, Chorisia crispiflora

Abstract

Three cytotoxic 6-substituted 5,6-dihydro-2H-pyran-2-ones ( 1 -3) were ~solated from a Brazilian medicinal plant, Chorisia crispiflora. 1 was identlfred as argentilactone, and the structures of two new compounds (2 and 3) were determined on the basis of the physicochemical properties.In the course of our program to isolate new biologically actlve compounds from Brazilian medicinal plants,' the methanol~c extract of Chorisia crispiflora (Bombacaceae) ("lnvira-tanha" or "Paine~ra" In Braz~l), one of the folk medicines used for rheumatism and menorrhalgia, was found to show a strong cytotoxic actlvtty against P-388 mouse leukernla cells.The invest~gatlon on the active princ~ples led to the ~solatlon of three cytotoxic compounds.In t h ~s paper, we report the ~solatlon and structure determinat~on of these compounds.The methanolic extract of the leaves of C. crispiflora was extracted w~th EtOAc and n-BuOH.A large portion of the cytotoxic activity passed into the EtOAc fraction, wh~ch was subjected to column chromatography on sllica gel repeatedly to afford compounds I, 11, and Ill.Compound I (1).[a], -18.O0(c 0.82, CHCIJ, was isolated as colorless 011, and the molecular formula C,,H,,O, was established by the HREl ms (m/z 194.1314,M' ) and ' ' C nmr spectrum.'The 'H nmr spectrum of 1 (Table )3 exhib~ted signals due to a primary methyl group (6 0.89), five methylene groups (6 1.20 -2.40), a methine group ( 6 5.22).a cis double bond ( 6 5.56 and 6 5.66).and an enone group (6 6.05 and 6 6.90).Analys~s of 'H-'H and 'H-"C COSY spectra of 1 revealed the connect~on of all signals to give the partial structure A.