Isolation and Immunomodulatory Effect of Homoisoflavones and Flavones from Agave sisalana Perrine ex Engelm.

Three known flavones and seven known homoisoflavonoids were isolated from the methanolic extract of the leaves of Agave sisalana Perrine ex Engelm. Their structures were elucidated on the basis of spectroscopic analysis. The isolated compounds were also evaluated for immunopharmacological activity. PBMC were used as target cells, and cell proliferation was determined by H-3-thymidine uptake. (+/-)-3,9-Dihydroeucomin (4), dihydrobonducellin (5), and 5,7-dihydroxy-3-(4'-hydroxybenzyl)-4-chromanone (7) showed inhibitory effects on PBMC proliferation activated by PHA with IC50 values 19.4, 73.8, and 58.8 mu M, respectively. All three compounds significantly inhibited the production of IL-2 and IFN-gamma in activated PBMC in a concentration-dependent manner.