CHEMOTAXONOMIC INVESTIGATION OF TWO SPECIES OF SOLANUM SECT. BREVANTHERUM SEITHE (SOLANACEAE)

Solanum asperum Rich. and S. stipulaceum Roem. and Schult. both belong to Solanum sect. Brevantherum. Earlier, we isolated solasodine from the fruits of both the species and another spirosolane alkaloid aglycone, solaparnaine, only from the former. Recently, we detected solaparnaine in the fruits of S. stipulaceum. Solaparnaine has not been reported from any other species of Solanum as yet. In this study, we obtained three parent glycoalkaloids from the fruits of S. asperum, which were identified by physical (MS and ¹³C and ¹H NMR) and chemical methods as the known glycoalkaloids, solasonine and solamargine, and a new glycoalkaloid, 27-hydroxysolamargine. We also obtained two more glycolalkaloids from the stems and branches of S. stipulaceum, which have been identified with the help of MS, ¹³C and ¹H NMR spectroscopy to be solamargin and a tetraglycoside of solaparnaine. Thus, the absence of any report of the isolation or detection of solaparnaine from any other species belonging to the genus Solanum and the presence of the alkaloid in S. asperum Rich. and S. stipulaceum Roem. and Schult, both belonging to Solanum sect. Brevantherum, investigated until now, lend ample support to the possibility of this alkaloid being characteristic of the section.