From Gentiana kirilowi, Gentianaceae: Proskurnina, J. Gen. Chem. USSR 14, 1148 (1944), C.A. 40, 7213 (1946); from Anthocleista procera Afz. and Fagraea fragrans Roxb., Loganiaceae: Lavie, Taylor-Smith, Chem. Ind. (London) 1963, 781; Wan, Chow, J. Pharm. Pharmacol. 16, 484 (1964). Isoln from Slevogtia orientalis Gris., Gentianaceae, structure and synthesis: Govindachari et al., J. Chem. Soc. 1957, 551, 2725.