A New Coumarin from the Bark of Cryptocarya bracteolata

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A NEW COUMARIN FROM THE BARK OF Cryptocarya bracteolata

Nurdin Saidi,1* Khalijah Awang,2 and Mustanir Yahya1

Isolation of compounds from the bark of Cryptocarya bracteolata yielded a new coumarin, 6,7,8-trimethoxy3,4-dihydrocoumarin. The structure of the compound was elucidated from spectral data, including IR, UV, 1D NMR (13C, 1H, and DEPT), 2D NMR (HMQC, HMBC, and COSY), EI-MS, and ESI-MS techniques. Keywords: Cryptocarya bracteolata, Lauraceae, coumarin. Cryptocarya bracteolata Gamb. belongs to the genus Cryptocarya and family Lauraceae. The genus includes more than 350 species, and 19 species are found in Southeast Asia, mainly in Indonesia and Malaysia. This genus is distributed through the Noetropic, Afrotropic, Indomalaya, and Australia ecozones. C. bracteolata is an endemic plant distributed in lowlands and hill forests in Indonesia and Malaysia. Previously, researchers reported from this plant the structure of a known coumarin, 6,7,8-trimethoxy-2H-1benzopyran-2-one [1], two phenyl propanoids, ethyl 3-(2′-hydroxy-3′,4′,5′-trimethoxyphenyl) propanoate and ethyl 3-(2′-glucosyl-3′,4′,5′-trimethoxyphenyl) propanoate, and seven known alkaloids, (+)-lirioferine, (+)-bracteoline, (+)-reticuline, (+)-reticuline N-oxide, (–)-norargemonine, (+)-bisnorargemonine, and atheroline [2]. Further studies on this plant led to the isolation and identification of a new coumarin, named 6,7,8-trimethoxy-3,4-dihydrocoumarin. In this paper, we report on the structure of a new coumarin, 6,7,8-trimethoxy-3,4-dihydrocoumarin. Compound 1 was obtained as a white amorphous solid. MS (EI, 70 eV) m/z: 238, 210, 196, 181; MS-ESI m/z 239.2 [M + H]+ (calcd for C12H14O5, 238.0). The mass spectrum (EI-MS) revealed a molecular ion peak at m/z 238, implying the possible molecular formula C12H14O5. The peak at m/z 223 [M – 15]+ was due to the loss of the methyl group. The UV spectrum showed absorption maxima at 296 nm, which indicated the existence of a highly conjugated system. The IR spectrum showed absorptions at 2941 cm–1 (C–H aromatic) and 1649 cm–1, indicating the presence of an aromatic system, and the absorption at 1724 cm–1 indicated the presence of a carbonyl group. The 1H NMR spectrum is presented in Table 1. The PMR spectrum showed one aromatic proton signal of H-5 appearing as a singlet at δ 6.39. There are three methoxyl peaks observed as a singlet at δ 3.87, 3.83, and 3.73. The two methylene protons bound to H-3 resonate as dd on δ 2.52 and have coupling constant of J = 14.6 Hz and J = 7.3 Hz. The two other methylene protons are bound to H-4 with dd multiplicity, whose coupling constant is exactly identical to H-3 of J = 14.6 Hz and J = 7.3 Hz. Their position are in accordance with the COSY, HMBC, and DEPT spectra. The 13C NMR spectrum and DEPT experiment confirm the presence of three methyls, two methylenes, one methine, and six quaternary carbon signals in the molecule.

1) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Syiah Kuala, 23111, Banda Aceh, Indonesia, fax: +62 651 801 2505, e-mail: