| The complement system provides an important means to protect a host from foreign invasive organisms, such as bacteria, fungi, and viruses. It comprises more than 30 plasma and membrane-bound proteins. However, undesired complement activation results in various inflammatory diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), atherosclerosis and glomerulonephritis. The herb medicine of clearing heat plays an important role in the treatment of inflammatory and infectious diseases, with its anti-inflammatory, antimicrobial and immunomodulatory activities. Thus, we deduce that the Traditional Chinese Medicine of clearing heat attenuate inflammation by inhibition of the complement system.Anti-complement activity of root bark of Paeonia suffruticosa and aerial part of Glochidion eriocarpum used in traditional Chinese medicine to treat inflammatory conditions were selected for this study. The aim of this study was to investigate the bioactive compounds responsible for the anti-complement activity.1. Anti-complement constituents from Paeonia suffruticosaBioassay-guided fractionation of an ethanolic extract of root bark of P. suffruticosa showed that both the EtOAc-soluble and n-BuOH-soluble fractions possessed potent anti-complement activity. The two active fractions were further separated by a combination of silica gel CC, flash ODS column, Sephadex LH-20 chromatography and preparative HPLC to afford 67 compounds, including monoterpenes and its glycosides derivatives (1-28), acetophenone and its glycosides derivatives (29-46), galloyl glucose derivatives (47-52), and other types compounds (53-67). Among them, thirteen compounds were new natural metabolites and were established as suffrupaeoniflorins A (26), B (2), C (3), suffrupaeonidanins D (4), E (5), F (6), paeonolides A (29), B (30), C (31), D (32), E (33), F (34), and mudanoside C (60), respectively, by comprehensive NMR and HRESIMS analyses.Fifty-six isolates were evaluated for in vitro anti-complement activity and thirty-nine ones exhibited anti-complement effects with CH5o and AP50 values ranging from 0.03 to 2.671mM and 0.13 to 4.00 mM, respectively. Of these, paeoniflorigenone (1), resacetophenone (40), as well as galloyl glucose derivatives (47-52) exhibited potent anti-complement activity against the classical pathway with CH50 value ranging from 0.03 to 0.98 mM. Compounds 12,19,29 and 30 showed strong anti-complement activity against the classical and alternative pathway with CH50 and AP50 values ranging from 0.08 to 0.21 mM and 0.13 to 0.32 mM, respectively. Among monoterpene derivatives, paeoiflorin derivatives with a C-4 methoxy group (3,8, and 21) and all six paeonidanin derivatives (4-6 and 23-25) showed no inhibition. These results indicate that hydroxy substitution at C-4 is required for an inhibitory effect, and a methoxy group is deleterious. Furthermore, the two most potent compounds (12 and 19) contain a galloyl moiety, which might be a determining factor for optimum anti-complement activity. In addition, compounds 11, 14,18and 26 with a p-hydroxybenzoyl group at C-8 were more potent than 7,13, and 20 with an unsubstituted benzoyl group, suggesting that a hydroxy group on the benzoyl moiety enhances activity. Among acetophenone glycosides derivatives, compounds (31-32 and 35-36) possessing apiofuranosyl moiety tended to show stronger inhibitory activity than compounds (33-34 and 37-38) possessing arabinopyranosyl moiety, suggesting the kind of sugar can also affect the compound anti-complement activity.In a mechanistic study, paeoniflorigenone (1) interacted with C2 and C4; both, galloylpaeoniflorin (12) and galloyloxypaeoniflorin (19) acted on Clq, C3, and C5; suffrupaeoniflorin A (26) interacted with Clq, C3, C5, and C9, paeonolides A (29), C (31) interacted with Clq, C3, C4, and C5, while paeonolides E (33) acted on Clq, C2, and C3, penta-O-galloyl-D-glucopyranose (48) acted on Clq, C2, and C4 components in the complement activation cascade.2. Anti-complement constituents from Glochidion eriocarpumBioactivity-guided fractionation of a EtOAc-soluble fraction from Glochidion erio-carpum led to the isolation of five new compounds, glochidonol A (1), glochidol A (2), B (3), C (9), D (10), together with fourteen known ones. Their stuctures were determined on the basis of chemical methods and spectroscopic data. Of these compounds, rocymosin A(4), saccharumosides B(5), gallocatechin-3-O-(3-O-methyl) gallate(6), gallocatechin-3-O-gallate (7),1,3-di-O-galloyl quinic acid (11), davidioside A(12), isoeugenol-β-D-glucoside (13), 1-(4-hydroxy-3-methoxyphenyl)-1-methoxypropan-2-ol (14),4-methoxysalicylaldehyde (16),3-hydroxy-4-ethoxy-benzoic acid (17),3-hydroxy-4-ethoxy-5-methoxy benzoic acid (18) were ioslated from glochidion and catechin-3-O-(3-O-methyl) gallate (8), catechin (15) from Glochidion eriocarpum for the first time.Sixteen isolates were evaluated for in vitro anti-complement activity and ten ones exhibited anti-complement effects. Six Compounds (1,4,7 and 9-11) showed potent anti-complement activity against the classical and alternative pathway with CH50 and AP50 values ranging from 0.03 to 0.13 mM and 0.02 to 0.19 mM, respectively. While compounds (2,3,6 and 12) showed moderate anti-complement activity against the classical and alternative pathway with CH50 and AP50 values ranging from 0.28 to 0.55 mM and 0.37 to 0.87 mM. Compounds 2,3, and 4 showed t anti-complement activity while 5 had no inhibition effect, suggesting that the phenolic hydroxyl group is required for an inhibitory effect. Compound 7 showed more potent inhibition than 6, suggesting that the methoxy moiety weaken the anti-complement activity.In a mechanistic study, glochidonol A (1) interacted with Clq, C2, C3, and C4, glochidol A (2) interacted with C1q, C2, C3, C5 and C9, gallocatechin-3-O-gallate (7) interacted with C1q, C3, and C5, while glochidol C (9) acted on Clq, C2, C3, C4, C5 and C9.The finding of this study may partly explain the use of these two medicinal plants in traditional Chinese medicine for the treatment of complement-dependent inflammation disease. |
PDF Full Text Request