Chemical Constituents of Litsea szemaois
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CHEMICAL CONSTITUENTS OF Litsea szemaois
Lei Xiao,1 Xin-Yi Wang,2 Nian-Qi Yang,1 Zhen-Ru Xia-Hou,1 Ping Yang,1 Wan-Ling Luo,1 Yun-Song Wang,1* and Jing-Hua Yang1*
Litsea, the most diverse genera of flowering plants in the family Lauraceae, includes evergreen trees or shrubs widely distributed throughout tropical and subtropical Asia and North and South America. Many plants belonging to Litsea are used as folk medicine. Litsea szemaois is an endangered species endemic to southern Yunnan, China [1, 2]. However, the chemical constituents and pharmacological activities of L. szemaois are rarely studied. Previously, our phytochemical investigations on L. szemaois revealed the presence of steroids, megastigmane-type sesquiterpenoid glucosides, coumarin, flavonoids, and aromatic compounds [3]. As part of an ongoing research on biologically active constituents of Litsea genus, which find use in ethnomedicine as treatment for inflammatory diseases, this study continues our previous work on the isolation and purication of L. szemaois components. The leaves and twigs were collected in Yunnan in 2015 and were identified by Prof. Yu Chen, Kunming Institute of Botany, ACS. The powdered leaves and twigs of L. szemaois (10 kg) were repeatedly extracted with 95% EtOH at room temperature. The extract was then concentrated under reduced pressure to give a dark-brown syrup, which was suspended in H2O and successively partitioned with petroleum ether (PE), EtOAc, and n-BuOH. The EtOAc extract (100 g) was subjected to a series of chromatographic techniques, such as silica gel (mesh 200–300) and Sephadex LH-20 column chromatography. Nine compounds were isolated and identified based on UV, IR, and NMR spectra, including 2D NMR, which allowed complete assignment of the 1H NMR and 13C NMR data and direct comparison with authentic samples and the literature. The isolated compounds included five steroids, 7β-hydroxysitosterol (1), 3β-acetoxysitost-5-en-7α-ol (2), 3β-acetoxysitost-5-en-7-one (3), stigmast-4-en-6β-ol-3-one (4), and stigmast-4-en-3-one (5), and four aromatic compounds, 4-hydroxy-3-methoxybenzaldehyde (6), 4-hydroxy-3,5-dimethoxybenzaldehyde (7), vanillic acid (8), and syringic acid (9). To the best of our knowledge, all compounds were isolated from L. szemaois for the first time, and compounds 2–7 have not been reported before from the genus Litsea. 7β-Hydroxysitosterol (1), C29H50O2, white powder. 1H NMR (600 MHz, CDCl3, δ, ppm, J/Hz): 5.58 (1H, s, H-6), 3.85 (1H, d, J = 6.6, H-7), 3.54 (1H, m, H-3), 1.08 (3H, s, H-19), 0.93 (3H, d, J = 6.4, H-21), 0.85 (3H, t, J = 6.4, H-29), 0.83 (3H, d, J = 6.0, H-26), 0.80 (3H, d, J = 6.6, H-27), 0.69 (3H, s, H-18). 13C NMR (150 MHz, CDCl3 , δ, ppm): 37.0 (C-1), 31.6 (C-2), 71.5 (C-3), 41.8 (C-4), 143.5 (C-5), 125.5 (C-6), 73.4 (C-7), 39.6 (C-8), 48.3 (C-9), 36.5 (C-10), 21.1 (C-11), 43.0 (C-12), 40.9 (C-13), 56.0 (C-14), 26.4 (C-15), 28.6 (C-16), 55.4 (C-17), 11.8 (C-18), 19.2 (C-19), 36.1 (C-20), 19.0 (C-21), 34.0 (C-22), 29.2 (C-23), 45.9 (C-24), 26.2 (C-25), 18.8 (C-26), 19.8 (C-27),
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