Anti-Inflammatory and Anti-Osteoclastogenesis Activities of Different Kinds of Zanthoxylum bungeanum Seed Oil in Vitro.

Our previous study has exhibited that one kind of Zanthoxylum bungeanum seed oil (ZSO), extracted from Zanthoxylum bungeanum seed, had inhibitory effects on osteoclastogenesis. However, the anti-osteoclastogenesis activities of different kinds of ZSO are scarcely reported. Since inflammation is related to bone loss and osteoporosis, in this study, three kinds of ZSO, Zanthoxylum schinifolium Siebold et Zucc seed oil (ZSSO), Zanthoxylum armatum DC. seed oil (ZDSO) and Zanthoxylum bungeanum maximum seed oil (ZBSO), were obtained with Soxhlet extraction and their fatty acid constituents were detected by GC-FID. RAW264.7 macrophages induced by lipopolysaccharide (LPS) were used to evaluate the inhibitory effects of three kinds of ZSO on inflammation via detecting the expression levels of inflammatory factors by RT-qPCR. Moreover, RANKL-induced osteoclastogenesis was applied to demonstrate the anti-osteoclastogenesis activities of them through tartrate-resistant acid phosphatase (TRAP) staining and RT-qPCR. The GC-FID results exhibited that the highest constituent in ZSSO and ZDSO was oleic acid (OA) and palmitoleic acid (PLA), respectively. While linoleic acid (LA) and α-Linolenic acid (ALA) in ZBSO were dominant. At the concentration of 0.5 µL/mL, all three kinds of ZSO could decrease the expression levels of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-1 beta (IL-1ß) in LPS-induced macrophages. At the concentration of 0.25 µL/mL, only ZSSO could decrease the expression levels of iNOS and COX-2, which implied the inhibitory effects of ZSSO were stronger than other ZSOs. The number of RANKL-induced osteoclasts and the expressions of nuclear factor kappa-B (NF-κB), TNF-α and IL-6 in the cells were decreased after being treated with ZSOs at the concentration of 0.5 µL/mL, while the number of RANKL-induced osteoclasts after treated with ZBSO were less than those treated with other ZSOs, this indicated that the anti-osteoclastogenesis effect of ZBSO were stronger than other ZSOs. In conclusion, the fatty acid compositions of three major kinds of ZSO were compared and the content of unsaturated fatty acids especially ω-3 polyunsaturated fatty acids in ZBSO were the highest among them. All ZSOs tested had anti-inflammatory and anti-osteoclastogenesis activities. And their anti-osteoclastogenesis effects might be related to the suppression of the NF-κB pathway.

α-Linolenic Acid Inhibits RANKL-Induced Osteoclastogenesis In Vitro and Prevents Inflammation In Vivo.

Inflammation is an important risk factor for bone-destroying diseases. Our preliminary research found that Zanthoxylum bungeanum seed oil (ZBSO) is abundant in unsaturated fatty acids and could inhibit osteoclastogenesis in receptor activator of nuclear factor κB ligand (RANKL)-induced RAW264.7 cells. However, the key constituents in ZBSO in the prevention of osteoclastogenesis and its possible mechanism related to inflammation are still unclear. Therefore, in this study, oleic acid (OA), linoleic acid (LA), palmitoleic acid (PLA), and alpha-linolenic acid (ALA) in ZBSO, havingthe strongest effect on RANKL-induced osteoclastogenesis, were selected by a tartrate-resistant acid phosphatase (TRAP) staining method. Furthermore, the effects of the selected fatty acids on anti-inflammation and anti-osteoclastogenesis in vitro and in vivo were assessed using RT-qPCR. Among the four major unsaturated fatty acids we tested, ALA displayed the strongest inhibitory effect on osteoclastogenesis. The increased expression of free fatty acid receptor 4 (FFAR4) and ß-arrestin2 (ßarr2), as well as the decreased expression of nuclear factor-kappa B (NF-κB), tumor necrosis factor-α (TNF-α), nuclear factor of activated T-cells c1 (NFATc1), and tartrate-resistant acid phosphatase (TRAP) in RAW264.7 cells after ALA treatment were observed. Moreover, in ovariectomized osteoporotic rats with ALA preventive intervention, we found that the expression of TNF-α, interleukin-6 (IL-6), interleukin-1ß (IL-1ß), NFATc1, and TRAP were decreased, while with the ALA therapeutic intervention, downregulated expression of NF-κB, NFATc1, TRAP, and transforming growth factor beta-activated kinase 1 (TAK1) were noticed. These results indicate that ALA, as the major unsaturated fatty acid in ZBSO, could inhibit RANKL-induced osteoclastogenesis via the FFAR4/ßarr2 signaling pathway and could prevent inflammation, suggesting that ZBSO may be a promising potential natural product of unsaturated fatty acids and a dietary supplement for the prevention of osteoclastogenesis and inflammatory diseases.