A New N -Fatty Acyl Tryptamine from Annana atemoya
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A NEW N-FATTY ACYL TRYPTAMINE FROM Annana atemoya
C. T. Chang,1 C. L. Kao,2 H. C. Yeh,3 Z. Y. Fang,3 H. T. Li,3 and C. Y. Chen4*
A new N-fatty acyl tryptamine, N-nonadecanoyl-4,5-dihydroxytryptamine (1), was isolated from the stems of Annona atemoya. The structure of the new tryptamine-derived amide was elucidated by chemical and physical evidence. Keywords: Annona atemoya, fatty acyl, tryptamine. Annonaceae is a large family comprising about 135 genera and more than 2500 species distributed mainly in tropical and subtropical regions [1]. Chemically, this family is characterized by the presence of isoquinoline alkaloids, mainly aporphines. Atemoya is a fruit plant of the Annonaceae family, being a hybrid resulting from a cross between the “cherimoia” (Annona cherimolia Mill.) and the “pinha” or “fruta-do-conde” (Annona squamosa L.). It was achieved at the beginning of the century in Florida (USA), the crosses being repeated in other countries in order to obtain hybrids adapted to tropical climate, as A. squamosa, and subtropical, as A. cherimolia [2]. Previous phytochemical studies on this species have led to the isolation of several alkaloids [3]. To further understand the chemotaxonomy and to continue searching for biologically and chemically novel agents from Annonaceous plants, the stems of A. atemoya Hort. (A. cherimolia × A. squamosa) were chosen for further phytochemical investigation. In this paper, we report the isolation and structural elucidation of this new N-fatty acyl tryptamine. N-Nonadecanoyl-4,5-dihydroxytryptamine (1) was obtained as a white amorphous powder from CHCl3. Its moleular formula was deduced as C29H48N2O3 by HR-ESI-MS (m/z 495.3560 [M + Na]+; calcd 495.3563). The UV spectrum of 1 contained absorption bands typical of an indole moiety [4, 5]. The IR spectrum of 1 showed characteristic absorption bands due to the presence of hydroxyl (3400 cm–1) and carbonyl (1680 cm–1) groups. The structure of the dihydroxytryptamine moiety was suggested by the 1H NMR spectrum (Table 1), which exhibited ortho-coupling signals at δ 7.11 (1H, d, J = 8.4 Hz, H-7) and 6.70 (1H, d, J = 8.4 Hz, H-6) on the benzene ring, 6.92 (1H, br.s, H-2), and two typical methylenes at δ 3.44 (2H, t, J = 6.8 Hz, H-11) and 2.82 (2H, t, J = 6.8 Hz, H-10). The resonances of the acid moieties included those of the amide carbonyl (δ 172.4), the methylenes α and β to the amide function, one terminal methyl group, and those for the remaining methylenes of the aliphatic chain. An HMQC experiment permitted unequivocal assignment of all proton-bearing carbons, while an HMBC experiment allowed full NMR assignments of 1 (Table 1). Two hydroxyl groups were at C-4 and C-5. A COSY correlations was observed between H-6 and H-7 and between H-10 and H-11. The HETCOR experiment showed that the carbon signals at δ 25.6 for C-10, 39.9 for C-11, 111.7 for C-7, 112.5 for C-6, and 127.9 for C-2 were correlated to the proton signals at δ 2.82 for H-10, δ 3.44 for H-11, δ 7.11 for H-7, δ 6.70 for H-6, and δ 6.92 for H-2, respectively. OH
H N
10
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