Two new isoquinolone Alkaloids from Sauropus hirsutus

Sauropus androgynus (Euphorbiaceae) is a popular vegetable in Thailand. In 1995, the plant was associated with several cases of poisoning when used in a Taiwanese weight control method and the toxicity was attributed to its alkaloid content. We have therefore investigated a closely related Sauropus species, S. hirsutus. Extraction and isolation of chemical constituents from the aerial part of S. hirsutus was performed by means of various chromatographic techniques. Two new isoquinolone alkaloids named sauropine A [4-methoxy-2-methyl-7, 8-methylenedioxy-1 (2H)-isoquinolone] and sauropine B [4, 6-dimethoxy-2-methyl-7, 8-methylenedioxy-1 (2H)-isoquinolone] were isolated from the chloroform fraction. The presence of isoquinoline alkaloids as the major constituents in a Sauropus species was confirmed. Exhaustive phytochemical studies of Sauropus would substantiate this finding and provide concrete and useful chemotaxonomic information on this interesting plant genus.