Study On The Preparation Of Thick Shell Mussel Lipid Extract And Its Anti-arthritic Activity And Mechanism

Rheumatoid arthritis is a high morbidity autoimmune disease that causes chronic inflammation of the joints. It is one of the major diseases which can make the patients lose their labor force. Many studies have demonstrated that New Zealand green-lipped mussel freeze dried powder and lipid extract had strong anti-arthritic activity. They have been widely used as natural anti-arthritic nutritional supplements in the treatment of rheumatoid arthritis and osteoarthritis. In the present research, the acute and chronic anti-inflammatory activity of the thick shell mussel (originated from Shengsi Island in Zhejiang province) freeze dried powder and lipid extract, and the anti-arthritic activity and mechanism of thick shell mussel lipid extract and thick shell mussel lipid extract+indomethacin were studied. Besides, the nutritional value of thick shell mussel and the supercritical CO2 fluid extraction of thick shell mussel lipid extract were also investigated. The outcomes are as follows:1. Thick shell mussel has a high nutritional value. It is rich in all kinds of essential amino acids and taurine. It is also rich in macro and micro mineral elements, especially Zn and Se. The relative percentages of n-3 polyunsaturated fatty acids are very high, among which, EPA+DHA accounts for 31.8%of the total fatty acids.2. The optimal supercritical CO2 fluid extraction conditions of thick shell mussel lipid extract are:extraction pressure 35 MPa, extraction temperature 49℃, CO2 flow rate 28 kg/h, extraction time 130 min. The extraction rate in the optimal condition is 5.65%.3. Both thick shell mussel freeze dried powder and lipid extract can't inhibit the ear edema induced by dimethylbenzene in mice, and have no effect on the celiac micro-capillary permeability induced by acetic acid in mice, and have little effect on the paw edema induced by carrageenin in rats. This indicates that thick shell mussel freeze dried powder and lipid extract have no acute anti-inflammatory activity.4. Both thick shell mussel freeze dried powder and lipid extract can inhibit the granulation hyperplasia induced by cotton-pill-implantation and the paw edema induced by adjuvant in rats. The inhibitory activity shows dose-response relationship. This indicates that thick shell mussel freeze dried powder and lipid extract have strong chronic anti-inflammatory activity. The chronic anti-inflammatory activity of thick shell mussel lipid extract is similar to New Zealand green-lipped mussel lipid extract.5. Thick shell mussel lipid extract has strong anti-arthritic activity. It can inhibit the paw and spleen edema, decrease the arthritic indexes, ameliorate the ankle joint pathological symptoms, and increase the growth rates of adjuvant-induced and collagenⅡ-induced arthritic rats. Thick shell mussel lipid extract shows similar anti-arthritic activity to New Zealand green-lipped mussel lipid extract.6. Combining thick shell mussel lipid extract with indomethacin not only significantly enhance the anti-arthritic activity, but also prevent the decrease of endogenous PGE2 and TXB2 caused by indomethacin, so as to protect the digestive system from damage which is caused by indomethacin.7. The anti-arthritic mechanisms of thick shell mussel lipid extract are:(1) Decrease the production of arachidonic acid 5-lipoxygenase and cyclooxygenase-2 metabolites (inflammatory mediators)—leukotriene B4 (LTB4), prostaglandin E2 (PGE2) and thromboxane B2 (TXB2) in the serum of adjuvant-induced and collagenⅡ-induced arthritic rats, so as to prevent the development of arthritis.(2) Decrease the production of pro-inflammatory cytokines—interleukin-1pβ(IL-1β), interleukin-6 (IL-6), tumor necrosis factor-a (TNF-a) and interferon-y (INF-y), but increase the production of anti-inflammatory cytokines—interleukin-4 (IL-4) and interleukin-6 (IL-6) in the serum and ankle joint synovial fluid of adjuvant-induced and collagenⅡ-induced arthritic rats, so as to prevent the abnormal immune response occurred in arthritis.(3) Decrease the mRNA expression of matrix metalloproteinase 1 and 13 (MMP1 and MMP13), but increase the mRNA expression of tissue inhibitor matrix metalloproteinase 1 (TIMP1) in the ankle joint synovium tissue of adjuvant-induced and collagenⅡ-induced arthritis rats, switch the MMPs/TIMPs balance in favor of TIMPs, so as to prevent the degradation and destruction of articular cartilage by MMPs.(4) Decrease the mRNA expression of the mitogen-activated protein kinases (MAKPs) signal pathways related signal molecules—p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2) and c-jun n-terminal kinase 3 (JNK3) in the ankle joint synovium tissue of collagenⅡ-induced arthritis rats, so as to inhibit the production of inflammatory mediators, pro-inflammatory cytokines, chemokines and MMPs mediated by MAPKs signal pathways.