Steroidal Glycoalkaloids and Molluscicidal Activity of Solanum asperum Rich. Fruits

Solanum L. (Solanaceae) is distributed mainly throughout the tropical and subtropical regions of the world and is the largest and most complex genus of the family Solanaceae. In Brazil, Solanum is represented by about 350 species. In this region, many species of Solanum are widely used in popular medicine and are commonly known as ‘yubeba’, the word derived from Tupi Guarani that refers to the prickles found on the stems of several of the species. Some common and wide-spread Solanum species of Brazil had shown considerable molluscicidal activity demonstrated by several members of the genus investigated earlier. Thus, we have been studying various species of Solanum growing in our country with the expectation that the extracts of plants of this genus might be useful in the control of Biomphalaria glabrata, the intermediate host of Schistosoma mansoni, the parasite that causes human schistosomiasis in Brazil. In our previous bioassays, the crude MeOH extract of the unripe fruits of S. asperum Rich showed activity in studies with Artemia salina (LC 50 = 420.5 g mL) and Biomphalaria glabrata (LC 50 = 25.5 g mL). Bioassay-guided fractionation indicated that the activity was concentrated in the alkaloid fraction. Thus, the alkaloid fraction upon CC on Sephadex LH-20 followed by PTLC on Silica gel afforded a new compound, solanandaine, C 45 H 73 O 16 N (1) mp 262-263 °C, [ ] D -60.0 (MeOH, c = 1.0 mg mL) along with solasonine (2) and solamargine (3). In this work, we wish to report the isolation, characterization and the molluscicidal activity of the alkaloids of S. asperum unripe fruits.