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60. Gebul-t\lng gcwidmet Q3.III. 77)AIstoniu scholaris: The structure of the indole alkaloid nareline SummaryBesides the known akuammidine, picralinal, picrinine and pseudoakuammigine a new indole alkaloid called nareline ( M = 352) was isolated from A lstonia scholaris R. BR., which belongs to the plant family of Apocynaceae. Its structure 2 was deduced by single crystal X-ray diffraction. 2 represents the absolute configuration. The spectroscopic data of 2 and its derivatives (Scheme 1) as well as their chemical behavior support this structure. In biogenetic sense nareline is related to the bases akuammiline (4) and picraline (5) (Scheme 2). In contrast to those the C-atom 5 is exocyclic and represents an aldehyde group which forms together with the oxygen atom of the N(4)-hydroxylamine group a cyclic half acetale. -By oxidation (CrO,/ CH,COOH) of 2 the oxindol derivative 19 (oxonareline) is formed which contains a cyclic acetal as a partial structure element (Scheme 4). Alstonia scholaris R. BR. ist eine in Indien beheimatete

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Two new lanostane-type triterpenes, 1 and 2, were isolated from Astraeus hygrometricus. The structures were established by IR, (1)H- and (13)C-NMR, MS, and X-ray crystallographic experiments. The triterpenes exhibited excellent in vitro toxicities against Candida albicans, comparable to standard antifungal antibiotics. The triterpene 2 significantly inhibited the growth of Leishmania donovani promastigotes in vitro. The triterpene skeleton may be considered a template structure in search for new compounds with anticandidal and leishmanicidal activity.

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