Studies on the Steroidal Sapogenins of the Subcellular Organelles of Dioscorea bernoulliana tubers

Abstract

Tubers of mature Dioscorea bernoulliana were homogenized and the homogenates were separated into cell wall, nuclear, mitochondrial, microsomal and supernatant fractions by means of differential centrifugation. The microsomal and mitochondrial fractions contained the bulk of the steroidal sapogenins of the tissue. The supernatant fractions contained only the trace amount of steroidal sapogenins. The cell wall and nuclear fractions contained the largest percentage of kryptogenin, while the microsomal fraction contained the largest percentage of diosgenin. The composition of other steroidal sapogenins varied widely among subcellular fractions. The yield of diosgenin increased, on a dry weight basis, with a decrease in particle size. The microsomal and mitochondrial fractions possessed stronger haemolytic activities and to a certain extent were stronger foaming agents than those of the cell wall and nuclear fractions. Sapogenins of the mitochondrial and microsomal fractions were released into the medium by their incubation with trypsin and α-glucosidase. These results support the suggestion that steroidal sapogenins are bound to the membranes of subcellular organelles