Studies on the evaluation of crude drug. I. Quantitative estimation of anthraquinones in Cassia seeds.

A method of the quantitative estimation of anthraquinones in Ketsumeishi was established and the change of anthraquinone contents in the seeds of Cassia obtusifolia L. and C. tora L. with various grade of maturity and ageing was studied. Also, the quantitative estimations of anthraquinones in Ketsumeishi samples obtained from various places were made. The absorbance of the alkaline extract after treatment with 5% sodium hydroxide solution containing 2% ammonia was measured at 520 nm, using 1, 8-dihydroxyanthraquinone as a standard. The optimum time for measurement was between 60 and 180 min after the completion of alkaline extraction and the optimum time for hydrolysis was 75 min. The recovery rate in the standard addition test was 97.0%. In the progress of maturity of the seed, the amount of free anthraquinones decreased and the amount of bound anthraquinones increased gradually, although the total amount was constant. The contents of both free and bound anthraquinones of fresh seeds were lower than those of the seeds preserved for 1 to 9 years. In Ketsumeishi samples, the contents of free anthraquinones were 0.01-0.04%, those of bound anthraquinones 1.01-1.29%, and the total contents varied from 1.04 to 1.31%. It was suggested that the crude drugs obtained from different places might be classified into two groups according to the contents of anthraquinones.