Studies On Anti-inflammatory Constituents Of Picrasma Quassioides Bennt

Picrasma quassioides Bennt (Simarubaceae) is a traditional Chinese medicine mainly distributed in South China. As an important folk medicine for many combination Qingrejiedu medicines, it has been used for treatment of clearing heat, dampness, detoxication, and snakebite for a long time. The effective components of P. quassioides and the mechanism of its components preventing and curing diseases, however, has not been reported. Anti-inflammatory activity-guided isolation of the stems of P. quassioides was carried out.48 compounds were isolated from the anti-inflammatory CHCl3-soluble fraction. Furthermore, these compounds were evaluated for their anti-inflammatory activity in vitro, which lay foundation for the anti-inflammatory mechanism of P. quassioides.The CHCl3-soluble fraction, which showed the most potent inhibitory activity on nitric oxide (NO) production in mouse monocyte-macrophage RAW 264.7 stimulated by LPS, was determined as the key bioactive fraction and was further isolated and purified by silica gel, Sephadex LH-20, MPLC-ODS, reversed phase HPLC, and other chromatographic methods to yield 48 compounds. Their structures were elucidated by IR, UV, ESIMS, HRESIMS, NMR, X-ray diffraction and other spectroscophic methods, including 25β-carboline alkaloids,6 canthinone alkaloids,11 bis-β-carboline alkaloids,3 lignins,2 quassinoids, and a flavonol. Among the 48 compounds,20 new compounds were determined as 3-(1,1-dimethoxylmethyl)-β-carboline (1), 6,12-dimethoxy-3-(2-hydroxylethyl)-β-carboline (2), 6,12-dimethoxy-3-(1,2-dihydroxylethyl)-β-carboline (3), 6,12-dimethoxy-3-(1-hydroxylethyl)-β-carboline (4), 6-methoxy-3-(2-hydroxyl-1-ethoxylethyl)-β-carboline (5), 3,4-dihydro-10-hydroxyl-3-oxo-β-carboline (6),6,12-dimethoxy-3-formyl-β-carboline (7), canthinone-14-butyric acid (26),14,15-dimethoxy-10-hydroxy-canthinone (27), quassidine A (32), quassidine I (33), quassidine F (34), quassidine G (35), quassidine C (36), quassidine B (37), quassidine D (38), quassidine H (39), quassidine E (40), picrasmalignan A (43), and 2’-isopicrasin A (46), respectivley. Quassidine A (32) was a new type bis-β-carboline alkaloid from the nature, the twoβ-carboline moieties in the structure of compound 32 were connected together by a novel cyclobutane moiety; and quassidine E (40) was also a new type bis-β-carboline alkaloid from the nature, the canthinone moiety and theβ-carboline moiety in the structure of compound 32 were connected together by a carbon-carbon single bond. Meanwhile, 6-methoxy-12-hydroxy-3-methoxycarbonyl-β-carboline (8) and 3,4-dihydrogen-3-oxo-β-carboline (9) were two new natural products; 9-hydroxy-canthinone (28), buddlenol A (44), buddlenol C (45), and fisetin (48) were four compounds isolated from Picrasma genus for the first time.The plausible biogenetic pathways of bis-β-carboline alkaloids were proposed in this paper for the first time on the basis of detailed analyses of the isolated and reported bis-β-carboline and monomicβ-carboline alkaloids.The anti-inflammatory activity evaluation of the 48 compounds from P. quassioides provided several new anti-inflammatory compounds. Compounds 1,7,14-16,21-23,27,34,35,40,43-45, and 48 showed potent inhibitory activity on nitric oxide (NO) production in mouse monocyte-macrophage RAW 264.7 stimulated by LPS, compounds 3,15,16,22,23,26,27,35,40, 43-45, and 48 showed potent inhibitory activity on tumor necrosis factorα(TNF-α) production in mouse monocyte-macrophage RAW 264.7 stimulated by LPS, and compounds 14-18,21-23,27,34, 35,43-45, and 48 showed potent inhibitory activity on interleukin 6 (IL-6) production in mouse monocyte-macrophage RAW 264.7 stimulated by LPS. Inhibitory effects of the 48 compounds on Phosphodiesterase-4 (PDE4) suggested that most of them showed no significant inhibitory activity on PDE4, comparing with the positive control rolipram. The above bioactive evaluation suggested that these compounds isolated from P. quassioides took roles on anti-inflammatory activity by inhibiting inflammatory factors’production, such as NO, TNF-α, and IL-6, not by inhibiting PDE4.