Chemical Constituents and Antitubercular Activity from the Stem of Engelhardia roxburghiana

• Main Authors: Ho-Chen Wu, 吳和澄
• Other Authors: Ih-Sheng Chen
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/56857263430447803250

碩士 === 高雄醫學大學 === 藥學研究所 === 99 === Engelhardia roxburghiana Wall. (Juglandaceae) is a deciduous tree, distributed in India, Indochina, SW China, and low to middle altitudes of Taiwan. Approximately 1300 species of Formosan plants have been screened for antitubercular activity against Mycobacterium tuberculosis H37Rv in vitro, and E. roxburghiana was shown to be one of the active species. Previous investigations from our laboratory, eleven new compounds, and twenty-nine known compounds have been isolated from the root of this plant, among them, 2-methoxyjuglone, 3-methoxyjuglone, engelharquinone, engelhardione, and (–)-4-hydroxy-1-tetralone were antitubercular constituents. The stem of this plant also showed antitubercular activity. Bioassay-guided fractionation of the active EtOAc-soluble layer of the stem has led to the isolation of 32 compounds, including four new diarylheptanoids: (–)-engelheptanoxide A (1), engelheptanoxides B~D (2~4); two new cyclic diarylheptanoids: engelhardiols A~B (5~6); one new naphthoquinone dimer: engelharquinonol (7), one first isolated from nature: (4S)-4,6-dihydroxy-1-tetralone (8); along with twenty-four known compounds, including squamolone (9), rhoiptelol B (10), methyl gallate (11), (3R)-3'', 4''-epoxy-1-(4-hydroxyphenyl)-7-(3-methoxy- phenyl)heptan-3-ol (12), (2R)-3'', 4''-epoxy-2-hydroxy-1-(4-hydroxyphenyl)-7-(3-methoxy-phenyl)heptan-3-one (13), 1-(4-hydroxyphenyl)-7-(4-hydroxy-3-methoxyphenyl)heptane-3,5-diol (14), rhoiptelol C (15), (–)-syringaresinol (16), 7-hydroxycadalene (17), vomifoliol (18), 4-acetonyl-3,5-dimethoxy-p-quinol (19), (＋)-4-hydroxy-1-tetralone (20), 3-O-betulinic acid p-coumarate (21), engelhardione (3'',4''-epoxy-1-(4-hydroxyphenyl)-7-(3-hydroxyphenyl)heptan-3-one) (44), engeletin (47), katuranin (51), afzelin (57), 3-methoxyjuglone (63), engelharquinone epoxide (65), b-sitosterol (68), b-sitosterone (70), (–)-regiolone (74), 3-epi-betulinic acid (76) and 3-epi-betulinic acid acetate (77). Among the isolated, thirteen compounds (9~21) were first isolated from this plant .The structures of these compounds were determined by spectroscopic analysis. We also revised the structure of engelhardione from 3'',3''-epoxy-1-(4-hydroxyphenyl)- 7-(3-hydroxyphenyl)heptan-3- one to 3'',4''-epoxy-1-(4-hydroxyphenyl)-7-(3-hydroxy- phenyl)heptan-3-one. Among the isolates, (–)-engelheptanoxide A (1), engelhardiol A (5), engelhardiol B (6), squamolone (9), engelhardione (3'',4''-epoxy-1-(4-hydroxyphenyl)-7-(3-hydroxyphenyl)heptan-3-one) (44), katuranin (51), 3-methoxyjuglone (63) and engelharquinone epoxide (65) showed antitubercular activity with MIC 55.3, 25.0, 20.5, 20.5, 3.125, 27.0, 3.125 and 25.5 μg/mL, respectively.