Abstract:
Levan is a polymer of fructose molecules linked via beta-2-6 glycosidic bond. This biopolymer has a potential for applying in pharmaceutical, food and cosmetic industries due to its antibacterial, antitumor, and antioxidant properties. However, the previous research revealed that different levan molecular weights (MWs) might exhibit different levels of biological activities. The objective of this study aims to investigate the effect of different molecular weights (MWs) of levan on its anti-inflammatory. Initially, the culturing conditions of Bacillus subtilis such as media formulas, sucrose concentrations, and rate of shaking (RPM) were investigated to obtain different MWs of levan. From the results, three different MWs of levan were prepared which were M1 (>8x105 Da), M2 (1.5x104 Da), and M3 (5x103 Da), respectively. Based on MTT assay, these levans at the concentration range of 31.25-250 g/mL did not exhibit cytotoxicity to RAW264.7 macrophage cells. However, these three different MWs of levan did not show nitric oxide inhibitory effect in LPS-induced RAW264.7 cells. Therefore, no anti-inflammatory activity was observed from all of these levans. On the other hand, the three different MWs of levan stimulate the nitric oxide production suggesting their immunomodulatory effect. The results showed that M2 can stimulate the highest nitric oxide production when compared to M1 and M3, respectively. Different MWs of levan can therefore lead to different levels of immunostimulation effect. Altogether, the results from this study suggest that certain MWs of levan can be potentially used as a natural immune modulator.