20 (29) - lupene - 3a - ol and 20 (29) - lupene - 3 - on are pentacylic triterpenes isolated from Aegle marmelos Correa collected in Yogyakarta , Indonesia. Their molecular structures were confirmed in University Putra Malaysia. These compounds were compained from petroleum ether extrak of the plant.s stem bark.. This study invitigated the effects of the compounds on the B- hexoaminadase enzyme release from mast cell culture (RBL--2H3 cell line). DNP 234 BSA was used as immunologic inducer for the B - hexominidase release from the mast cells. The enzyme release was determinet by colometric methods with a a substrate, p-nytropenyl -2 acetamydo -2 deoxy B--B-gluko-pranocide,anda and a microplate reader at 405 nm....