Alkaloids from the leaves of Alstonia scholaris in Taiwan, Thailand, Indonesia and the Philippines☆

Abstract From the leaves of Alstonia scholaris , collected in Taiwan, Thailand, Indonesia and Philippines, several new alkaloids, 19-epischolaricine, N b -methylscholaricine, N a -methylburnamine and vallesamine N b -oxide were isolated and their structures determined by spectral and chemical methods. The leaves of plants from Taiwan and Thailand showed similar alkaloid patterns, with picrinine, nareline and alschomine as the major alkaloids. The leaves of plants from Indonesia and Philippines showed different patterns from those of plants from Taiwan or Thailand, and contained mainly angustilobine B group. Picraline and its homologues were obtained from the leaves of Indonesian plants.