Two new aloceramides from alocasia macrorrhiza

Two new aloceramides alomacrorrhiza A and alomacrorrhiza B were isolated from the ethanolic extract of the plant Alocasia macrorrhiza (L.) Schott. Their chemical structures were elucidated as (2S,3S,4R)-2N-[(2R)-2-hydroxy-hexacosanoyl]-tetradecane-1,3,4-triol (1) and (2S,3S,4R)-2N-[(2R)-2-hydroxy-hexacosanoyl]-hexadecane-1,3,4-triol (2) based on extensive 1D, 2D NMR, EI-MS, FAB-MS, HR-FAB-MS spectroscopic data and chemical degradation studies.
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Two new aloceramides from alocasia macrorrhizaJournal of Chemistry, Vol. 43 (4), P. 513 - 516, 2005 TWO NEW ALOCERAMIDES FROM ALOCASIA MACRORRHIZA Received 26th, July 2004 NGUYEN QUYET TIEN1, PHAM HOANG NGOC1, PHAM HONG MINH1, PHAN VAN KIEM2 AND YOUNG HO KIM3 1 Institute of Chemistry, Vietnamese Academy of Science and Technology 2 Institute of Natural Products Chemistry, Vietnamese Academy of Science and Technology 3 College of Pharmacy, Chungnam National University, Daejeon 305-764, Korea summary Two new aloceramides alomacrorrhiza A and alomacrorrhiza B were isolated from the ethanolic extract of the plant Alocasia macrorrhiza (L.) Schott. Their chemical structures were elucidated as (2S,3S,4R)-2N-[(2R)-2-hydroxy-hexacosanoyl]-tetradecane-1,3,4-triol (1) and (2S,3S,4R)-2N-[(2R)-2-hydroxy-hexacosanoyl]-hexadecane-1,3,4-triol (2) based on extensive 1D, 2D NMR, EI-MS, FAB-MS, HR-FAB-MS spectroscopic data and chemical degradation studies. Keywords: Araceae, Alocasia macrorrhiza, ceramide, alomacrorrhiza A, alomacrorrhiza B. I - INTRODUCTION polarimeter. EI-MS was obtained using a Hewlett Packard 5989 B MS spectrometer. FAB- Alocasia macrorrhiza (L.) Schott (Araceae) MS and HR-FAB-MS were obtained using ais widely distributed in Vietnam, and used as a JEOL JMS-DX 300 spectrometer. 1H-NMRfolk medicine to treat inflammation, eczema and (500 MHz) and 13C-NMR (125 MHz) wereabscess [2, 5]. Alocasin, an anti-fungal protein recorded on a Bruker AM500 FT-NMRand trypsin inhibitor has been isolated from the spectrometer and TMS was used as an internalgiant taro A. macrorrhiza [1, 3, 7]. We report standard. Column chromatography (CC) washerein the isolation and structural elucidation of performed on silica gel (Kieselgel 60, 70 - 230two new ceramides, (2S,3S,4R)-2N-[(2R)-2- mesh and 230 - 400 mesh, Merck).hydroxy-hexacosanoyl]-tetradecane-1,3,4-triol Plant material(1) and (2S,3S,4R)-2N-[(2R)-2-hydroxy-hexa-co-sanoyl]-hexadecane-1,3,4-triol, (2) from the The roots of A. macrorrhiza were collectedethanolic extract of A. macrorrhiza. in Hoabinh province, Vietnam in December 1999 and identified by Prof. Nguyen Tien Ban, II - MATERIALS AND METHODS Institute of Ecology, Biological Resources, Vietnamese Academy of Science andGeneral experimental procedures Technology (VAST). Voucher specimens are Melting points were determined using an deposited at the Institute Chemistry, VAST.Electrothermal IA-9200. IR spectrum was Extraction and isolationobtained on a Hitachi 270-30 type spectrometerwith KBr discs. Optical rotations were The dried and powdered roots of A.determined on a JASCO DIP-1000 KUY macrorrhiza (2.0 kg) were extracted three times 513with hot EtOH repeatedly to give ethanolic NMR (500 MHz, CDCl3) : 4.18 (H, br s, H-2),extract (210.0 g), which was suspended in water 3.79 (3H, s, CH3-O), 0.89 (3H, t, 8.7); 13C-NMRand extracted using hexane, chloroform, ethyl (125 MHz, CDCl3) : 175.8 (C-1), 70.4 (C-2),acetate and n-butanol, respectively. The ethyl 52.4 (CH3-O), 34.4 (C-3), 21.4 - 30.9 (C-4 toacetate extract (11.5 g) was subjected to C-13) and 14.1 (C-14).chromatography on a silica gel column, usingchloroform-methanol (9 : 1) as eluent to yield Acetylation of 1six fractions (Fr. A-F). Fraction C (1.2 g) was Compound 1 (4 mg) was added to dryfollowed by CC on a YMC RP-8 column using a pyridine (0.25 ml) and Ac2O (0.5 ml) and leftMeOH-H2O (10 : 1) as eluent to yield 1 (34.5 overnight. After usual workup, the reactionmg) and 2 (57 mg). mixture was chromatographed over silica gel(2S,3S,4R)-2N-[(2R)-2-hydroxy- [hexane-EtOAc (5 : 1)] to yield derivative 1ahexacosanoyl]-tetradecane-1,3,4-triol (1) (1.4 mg) as white crystals; mp 105 - 108oC; White amorphous powders; mp 112 - 114oC; [ ]25D +26.5o (c 0.1, MeOH); 1H-NMR (500[ ]25D +32.5o (c 1.00, MeOH); positive FAB-MS MHz, CDCl3) : 6.57 (d, J = 9.1 Hz, NH), 4.33 - 4.95 (m, 5H, carbinol protons), 2.18 (3H, s,m/z: 678.6 [M+Na]+; HR-FAB-MS m/z: OAc), 2.08 (3H, s, OAc), 2.05 (3H, s, OAc),678.6013 [M+Na]+ (Calcd for C40H81NO5Na: 2.02 (3H, s, OAc) and 0.88 (6H, t, J = 8.7 Hz).678.6012); 1H- and 13C-NMR (see table 1). Acetylation of 2(2S,3S,4R)-2N-[(2R)-2-hydroxy-hexacosanoyl]-hexadecane-1,3,4-triol (2) Compound 2 (4 mg) was acetylated as 1 to yield derivative 2a as white crystals; mp 108 - White amorphous powders; mp 107 - 109oC; 111 oC; [ ]D +31.0o (c 0.1, MeOH); 1H-NMR 25[ ]25D +42.5o (c 1.00, MeOH); positive FAB-MS (500 MHz, CDCl3) : 6.58 (d, J = 9.1 Hz, NH),m/z: 706.63 [M+Na]+; HR-FAB-MS m/z: 4.33-4.96 (m, 5H, carbinol protons), 2.19 (3H, s,706.6321 [M+Na]+ (Calcd for C42H85NO5Na: ...