Design, Synthesis And Anti-inflammatory Evaluation Of Plant Polyphenols-Functionalized Nonsteroidal Anti-inflammatory Drugs

Nonsteroidal anti-inflammatory drugs (NSAIDs) possessing a free carboxylic acid group are used as over the counter (OTC) drugs for the treatment of inflammatory and immune diseases, such as rheumatoid arthritis, pain, and cancer. However, oral administration of NSAIDs is frequently associated with serious adverse effects in patients. The common events following oral administration of NSAIDs are gastric mucosal and renal damage. Novel anti-inflammatory agents are urgently needed for clinical application. Inspired by Curcuma longa and Magnolia officinalis, natural traditional Chinese medicine, which contains curcumin and magnolol respectively, novel anti-inflammatory agents were developed by linking curcumin or magnolol with NSAIDs to improve their activities and reduce adverse effects. Firstly, a series of curcumin or magnolol derivatives containing NSAIDs were designed, synthesized and screened for their anti-inflammatory activities in vitro by MTT assay and in vivo by using TPA-induced mouse ear edema model respectively. Secondly, immunohistochemical analysis revealed that All, B13 and C7 suppressed TPA-induced IL-1β, IL-6 and TNF-α expression respectively. Moreover, All, B13 and C7 were selected to elucidate the anti-inflammatory mechanism, suggesting their potential to serve as novel anti-inflammatory agents.In this thesis, firstly, inspired by curcumin and magnolol-plant polyphenols, several series of curcumin or magnolol derivatives containing NSAIDs (Series A, B, C and D) were synthesized through one-step esterification, and the chemiacal structures of the synthezied compounds were confirmed by 1H-NMR,13C-NMR and LC-MS.Secondly, inhibitory effects of these compounds (Series A, B, C and D) on the proliferation of RAW 264.7 cells were determined by using the MTT [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. These results demonstrated that the majority of cucumin or magnolol derivatives containing NSAIDs had stronger inhibitory effect on RAW 264.7 than curcumin or magnolol respectively. In addition, the inhibitory effects of A5 and C11 on RAW 264.7 cell line were stronger than that of other compounds. Structure-activity relationship (SAR) studies revealed that inhibitory effect of A5 on RAW 264.7 cell line was the more potent than that of other curcumin derivatives containing fenamic acid NSAIDs. The possible reason for this was that the hydrogen atom was replaced with -CF3 (an electron-withdrawing substituent) at the meta-position on the benzene rings (A5) increased activity against RAW264.7 cell line compared with 4-chlorophenyl compound (A13) and 4-methylphenyl compound (A8). Moreover, it was indicated that the anti-inflammatory activities of curcumin derivatives containing mono-NSAIDs (c, e, f, g, h, l, k, m) are better than that of curcumin derivatives containing bis-NSAIDs. In addition, the anti-inflammatory activities of all of magnolol derivatives containing bis-NSAIDs are better than that of magnolol derivatives containing mono-NSAIDs.To investigate whether curcumin and magnolol derivatives containing NSAIDs have any anti-inflammatory activitives, their effects on TPA-induced mouse ear edema were determined. The results showed that the inhibitory effects of 23 curcumin-NSAIDs compounds were found to be more potent than that of curcumin, and the inhibition of 20 magnolol-NSAIDs compounds were found to be more potent than that of magnolol. A5, A6, A11, B4, B6 and B13 exhibited stronger decreases in the average weight of ear punches than curcumin did (up to 90% decrease). Moreover, C2, C3, C6, C7, C9, D4, D7 and D9 exhibited stronger decreases in the average weight of ear punches than magnolol did (up to 90% decrease). SAR studies revealed that the most potent curcumin derivatives containing salicylic acid NSAIDs, propionic acid NSAIDs, and fenamic acid NSAIDs against mouse ear edema are B13, A6 and A5, respectively. In addition, the most potent magnolol derivatives containing propionic acid NSAIDs and salicylic acid NSAIDs against TPA-induced mouse ear edema are C7 and C3. The anti-inflammatory activities of curcumin derivatives containing mono-NSAIDs (b, e, f, g, h, k,l, m) are better than that of curcumin derivatives containing bis-NSAIDs. Additionally, the anti-inflammatory activities of magnolol derivatives containing mono-NSAIDs (b, c, e, g, h, i, k,l) are better than that of magnolol derivatives containing bis-NSAIDs. Moreover, the further studies indicated that the inhibitory effects of All and B13 on decrease in the weight of punches were the most potent than that of salicylic acid or salsalate, combination of curcumin and salicylic acid (1:1, mol/mol) or curcumin and salsalate (1:2, mol/mol), respectively. And the inhibitory effect of C7 on decrease in the weight of punches was the most potent than that of ketoprofen, combination of magnolol and ketoprofen (1:1, mol/mol).Furthermore, compared with curcumin, magnolol or parental NSAIDs (salicylic acid, salsalate and ketoprofen), topical application of All, B13 and C7 onto mouse ear skin, prior to TPA treatment markedly suppressed the expression of IL-1β, IL-6 and TNF-α. Mechanistically, All, B13 and C7 blocked the phosphorylation of p65 and IκBα, suppressed the activation of p65 and IκBα and inhibited the activation of IKK. It was found that All, B13 and C7 may be potent anti-inflammatory agents for the treatment of inflammatory diseases.