The perchloric acid hydrolysis of a mixture of samins from the root bark of HEINSIA CRJNATA yielded three major genins. Their structures were established on thebasis of IR, NMR and Mass Spectmmetry. Twoofthemwereshown to be new triterpenes of the cycloartene snd lsnostene type with a 27-carboxylic group linked to the amino function of 4-hydroxyisoleucine in its 7-la&one form. Beinsia crinata (Rubiaceae) is a wild plsnt widely used in folk African medicine againstgonorrhoea anddiarrhoea. The crude drug is also used as a sexual stimulsnt.1'2 Our chemical screening of the root bark of H. crinata indicated the presenceof saponins se major constituents of this drug. This paper describes the isolation of cNde saponins and the structure elucidation of three genins obtained by acid hydrolysis. RBsuLTsANDDISUK3SICN The crude saponins of I-l. crinata were isolated from methsnolic extracts of the mot bark using a sequence consisting of extraction with butanol-water and precipitation with isoproPy1 ether. Perchloric acid hydrolysis of these saponins afforded a mixture of genins. These genins were separated by combined column chromatography and Tu: on silica gel to give three crystalline compounds as major sapogenins along with several minor products. Compomd 1 was identified as quinovic acid by comparison of physical and spectroscopic data to those published.3-6 &m&WIld & (R=R), m.p.: 166-168ยฐC; t"lD : t138 (m13,C : l.O), wss characterized as the acetate &, m.p. : 142-C. ti the basis of the arprnents set forth below, we attributed to this compound a novel structure, featuring a 9,19-cyclolanostane skeleton snd sn (E,E)-22,24-dien-27-amide side chain (chart 1). The amino group forms part of a 4hydroxyisoleucine residue present in the x-la&one form.
In view of the all cis disposition observed for the three ring substituents, the absolute configuration may be assigned ss 2S, 3R, 4R, provided that the amino acid belongs to the L-series.