Alstonia venenata

Two other alkaloids 47 and 48 were isolated in addition to Neooxygambirtannine 44 (67T3129). Anhydroalstonatine from Alstonia venenata is a closely related structure (77IJC(B)183) (Scheme 18). 

The quaternary alkaloid anhydroalstonatine (70), which has a completely aromatic yohimbane ring system, has been isolated from Alstonia venenata R.Br. (64). 

Venoxidine (Venenatine N-oxide) Alstonia venenata R.Br. (85) 218-219 -82.4° (82a) C22H28N2O5... 

Epiallo Series. Among alkaloids containing the epiallo yohimbane skeleton, only 3-epi-a-yohimbine (105) was formerly known. In the past decade, four additional members of this alkaloid subgroup have been isolated, namely, quatematine (106) from Alstonia quaternata (84), venenatine (107) and its N-oxide (venoxidine) from Alstonia venenata R.Br. (79, 80, 82a, 85) and 16-epivenenatine (108) also from Alstonia venenata R.Br. (81). 

Vinca minor, cultivated in Georgia, USSR, has been shown to contain ( )-vincadifformine and vincine, both already known to occur in this species, together with apovincamine and 11-methoxyvincadifformine.92 Voaphylline, voaphylline hydroxyindolenine, and 11-hydroxytabersonine have been isolated from the leaves of Tabernanthe pubescens,43/ and 5,22-dioxokopsane (177) from the root bark of Alstonia venenata R. Br. 93 this is the first report of an alkaloid of the heptacyclic kopsine group in this species. 

Govindachari et al. have recently recorded the extraction of reserpine, venenatine (LXXVII), and 3-isovenenatine from the bark of Alstonia venenata R. Br. (98). 3-Isovenenatine may be identical with alstovenine, isolated earlier from the same species by Ray and Chatterjee (99), together with a second, unnamed base, m.p. 192°. 

Echitoveniline (102), 11-methoxyechitoveniline (103), and 11-methoxyechitovenidine (104) are three new alkaloids from the fruits of Alstonia venenata R. Br. (135,136), although the leaves are a better source of 103. In consonance with these structures, ester exchange with sodium methoxide affords (-)-19R-minovincinine (80) from 102, and (—)-19/ -ll-methoxyminovincinine, a minor alkaloid of Vinca minor (137), from 103 and 104. 

Veneserpine from Alstonia venenata is identical with reserpine except that the trimethoxybenzoyl unit is replaced by a 3,4-methylenedioxy-5-methoxybenzoyl group. An n.m.r. study has elucidated the full relative stereochemistry of tetraphyllinine (38) from Rauwoljia discolor. 

Alstonia venenata R.Br. Apocynaceae W.Pen ripe fruit epilepsy 50. 51... 

Echitovenaldine was obtained from the leaves of Alstonia venenata R. Br. by Majumder and co-workers (21). The UV spectrum (Amax 328 nm) and the IR spectrum ( max 3300, 1675, and 1610 cm-1) indicated an anilinoacrylate derivative, and three proton singlets at 3.77 (- 02 ),... 

Continuing with the isolation of alkaloids from the fruits of Alstonia venenata, Majumder et al. have obtained two unusual /3-anilinoacrylate bases, echitoserpine (34) (24) and echitoserpidine (35) (25). Because these alkaloids are so closely related they will be discussed together, although the main emphasis will be on echitoserpidine. The UV and IR spectra, and the characteristic chromogenic reaction with ceric ammonium sulfate, indicated the presence of the anilinoacrylate chromophore, but the IR spectrum also indicated the presence of an ester carbonyl (1720 cm-1). Six aromatic protons were discerned, but the pattern was too complex for... 

Apocynaceae—continued Alstonia specfabilis R. Br. Alstonia venenata R. Br. 

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