Chemical Constituents of Arabidopsis thaliana

Abstract

Arabidopsis thaliana (L.) Heynh. has become a model system for studying many aspects of plant biology and biochemistry. Studies on the chemical constituents have previously led to the isolation of flavonoids [1, 5], oxylipins [2–5], and alkaloids [5] from A. thaliana. The wild herbs of Arabidopsis thaliana were collected from Jiande, Zhejiang, P. R. China, in 2009. A voucher specimen was deposited in the Herbarium of Materia Medica, School of Pharmacy, Second Military Medical University, Shanghai, P. R. China. The dried and powdered material (5 kg) was extracted with 95% EtOH at room temperature. The combined extract was then suspended with water and extracted three times with ethyl acetate, then purified by column chromatography with silica gel to yield compounds 1–7. The compounds were identified using UV, IR, and NMR spectral data and determined as camalexin (1) [6], methyl 1-methyl-1H-indole-3-carboxylate (2) [7, 8], methyl 1H-indole-3-carboxylate (3) [9, 10], 1-methoxy-3-indolecarbaldehyde (4) [11, 12], 4-hydroxy-3-methoxybenzaldehyde (5) [13, 14], phthalic acid isodibutyl ester (6) [15, 16], and -tocopherol (7) [17]. Compounds 1–3 and 5–7 were isolated from A. thaliana for the first time. The 13C NMR signals of compounds 2 were assigned by 1D and 2D NMR for the first time. Camalexin (1). Colorless needles, mp 135–139 C. 1H NMR (400 MHz, CDCl3, , ppm, J/Hz): 9.40 (br.s, N-H), 8.27 (d, J = 7.84, H-4), 7.88 (d, J = 3, H-4 ), 7.84 (d, J = 2.5, H-2), 7.44 (m, H-7), 7.35 (m, H-6), 7.34 (m, H-5), 7.29 (d, J = 3, H-5). 13C NMR (100 MHz, CDCl3, , ppm): 163.6 (s, C-2 ), 142.2 (d, C-2), 136.5 (s, C-7a), 124.9 (s, C-3a), 124.6 (d, C-4 ), 123.1 (d, C-5), 121.4 (d, C-6), 120.4 (d, C-4), 116.1 (d, C-5 ), 112.0 (s, C-3), 111.8 (d, C-7). Methyl 1-Methyl-1H-indole-3-carboxylate (2). White powder. 1H NMR (400 MHz, CDCl3, , ppm): 8.20 (m, H-4), 7.80 (s, H-2), 7.38 (m, H-7), 7.34 (m, H-5), 7.31 (m, H-6), 3.93 (s, OCH3), 3.85 (s, NCH3). 13C NMR (100 MHz, CDCl3, , ppm): 165.5 (COOCH3), 137.2 (s, C-7a), 135.2 (d, C-2), 126.6 (s, C-3a), 122.8 (d, C-5), 121.9 (d, C-6), 121.7 (d, C-4), 109.8 (d, C-7), 106.9 (s, C-3), 51.0 (q, OCH3), 33.5 (NCH3). Methyl Indole-3-carboxylate (3). White powder. 1H NMR (400 MHz, CDCl3, , ppm, J/Hz): 8.65 (br.s, N-H), 8.21 (m, H-4), 7.96 (d, J = 1.12, H-2), 7.45 (m, H-7), 7.32 (m, H-5), 7.30 (m, H-6), 3.95 (s, OCH3). 13C NMR (100 MHz, CDCl3, , ppm): 165.6 (s, COOCH3), 135.9 (s, C-7a), 130.9 (d, C-2), 125.8 (s, C-3a), 123.3 (d, C-5), 122.1 (d, C-6), 121.6 (d, C-4), 111.5 (d, C-7), 108.9 (s, C-3), 51.1 (q, OCH3). Compound 3 displayed significant growth inhibition against K562 human chronic leukemia [18]. 1-Methoxy-3-indolecarbaldehyde (4). Yellow oil. 1H NMR (400 MHz, CDCl3, , ppm): 9.99 (CHO), 8.34 (m, H-7), 7.92 (s, H-2), 7.51 (m, H-4), 7.41 (m, H-6), 7.36 (m, H-5), 4.20 (s, OCH3). 13C NMR (100 MHz, CDCl3, , ppm): 184.2 (s, CHO), 132.6 (d, C-7), 131.7 (d, C-2), 124.6 (d, C-5), 123.5 (d, C-4), 122.2 (s, C-3a), 121.6 (s, C-7a), 114.1 (s, C-3), 108.7 (d, C-6), 66.9 (q, OCH3). 4-Hydroxy-3-methoxybenzaldehyde (5). White powder. 1H NMR (400 MHz, CDCl3, , ppm, J/Hz): 9.85 (CHO), 7.44 (1H, d, J = 1.6, H-2), 7.07 (1H, d, J = 8.5, H-5), 7.46 (1H, dd, J = 8.5, 1.6, H-6), 6.20 (br.s, 4-OH), 3.99 (s, OCH3). 13C NMR (100 MHz, CDCl3, , ppm): 190.6 (s, CHO), 151.6 (s, C-4), 147.1 (s, C-3), 129.9 (s, C-1), 127.5 (d, C-6), 114.4 (d, C-2), 108.7 (d, C-5), 56.1 (q, OCH3).