Adina rubescens

Adirubine (66), the first member of a new series of 5p-carboxy alkaloids having a corynane skeleton, has been isolated from Adina rubescens by Brown et al. (60). The first structure elucidation of adirubine, based on spectral data only, was incomplete (60). Final determination of the steric arrangement around ring D was performed by correlation with 5 p-methoxycarbonyldihydromancunine, and it proved to be alio (3a, 15a, 20a) (67). 

In 1975, Brown and Charalambides (62) reported the isolation of anhydroadirubine (68), also from Adina rubescens, as a methyl ester derivative (69). 

Carboxycorynanthine (87) Adina rubescens (71), methyl ester 235 -29° (71) C23H2gN205... 

As far as biosynthesis is concerned, it is clear that lyaloside (23) and pauridianthoside (26) readily derive from strictosidine (17). These three molecules display identical stereochemistry at the three chiral centers, namely, a,a,(3 for the hydrogen atoms at the 15, 20, 21 positions, respectively. They are closely related to a number of glucoalkaloids identified in Pertusadina euryncha (= Adina rubescens), e.g., rubenine (31) and desoxycordifoline (34, R = H) (49), and in Adina cordifolia, e.g., cordifoline (34, R = OH) (50). Palinine (35),... 

A limited number of alkoyl-glucoalkaloids have been reported in the literature so far. The first specimen of this class of compounds to be isolated was rubescine (43), which was found in Adina rubescens (64). More recently another esterified vincoside lactam, rhynchophine (44), was extracted from the leaves of Uncaria rhynchophylla, a member of the tribe Cinchoneae (65). Thus, chemotaxonomic correlations again tend to raise the question whether Pauridiantha should not join, along with Adina and Uncaria, the tribe Naucleae. 

Macrolidine (70), from the heartwood of Adina rubescens, is a new glycosidic indole alkaloid in which the terminal primary alcohol function in a 5-carboxy-isovincoside derivative has formed a novel macrocyclic lactone ring with the retained tryptophan carboxy-group. The structure was deduced from the spectra of macrolidine and its tetra-acyl derivatives and confirmed by reaction of macrolidine tetra-acetate with methanolic sodium methoxide followed by re-acetylation, which gave the known methyl 3a,5a-tetrahydrodesoxycordifoline penta-acetate (71). 

Another member of the growing group of biosynthetically advanced alkaloids which still retain the tryptophan carboxyl group is provided by 5j8-carboxycorynanthine (74), a constituent of Adina rubescens ° The stereochemistry... 

Rewarding sources of monoterpene alkaloid glycosides have been the Asiatic tree Adina rubescens Hemsl. and related Rubiaceous plants A. cordifolia (Roxb.) Hook. f. ex Brandis (1, 2), Nauclea latifolia Sm. (3), N. diderrichii Merrill (4), and Anthocephalus cadamba Miq. (5). The heart-wood and bark of the first has yielded so far no less than nine glycoalkaloids... 

Vincoside lactam (27b), isolated from Adina rubescens, was converted (Scheme 7) " into a triol (30). Corynantheine (31) was degraded to a triol (32) which proved to be enantiomeric with the major vincoside lactam degradation product (30). 

Constit. of Adina rubescens, A. racemosa and Amoora rohituka. Needles (MeOH). Mp 275-280°. 5-0-p-D-Glucopyranoside [128396-15-6]. Schumanniofioside A... 

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