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Mesona chinensis Benth has been consumed as a functional food for many years. It is widely believed that storage times affect its health benefits. In this study, Mesona chinensis Benth polysaccharides with two different storage times (fresh and storage for 1 year) were prepared, namely, FMP and AMP. The physicochemical properties and bioactivity were comparatively assessed. Results indicated that FMP was mainly composed of galacturonic acid, galactose, and glucose with a molecular weight of 44.39 kDa. AMP was composed of galacturonic acid, galactose, and fructose with a molecular weight of 64.34 kDa. However, the principal structural characteristics of polysaccharides remained stable. Furthermore, assays of antioxidant activity showed that Mesona chinensis Benth polysaccharide had an antioxidant effect against DPPH radical, ABTS radical cation, among which FMP was stronger. Additionally, flow cytometry indicated that the apoptosis rate of FMP and AMP on HepG2 tumor cells was 22.50 ± 1.25% and 15.49 ± 1.30%, respectively. In general, antioxidant and antitumor activities of Mesona chinensis Benth polysaccharides were decreased as the storage for 1 year. The change of physicochemical properties was responsible for the enhanced bioactivities. These results explained how polysaccharides contributed to the decreased health benefits of Mesona chinensis Benth during storage.

Global warming has prompted scientific communities to consider how to alleviate thermal stress in humans and animals. The present study assessed the supplementation of hsian-tsao extract (HTE) on thermal stress in Drosophila melanogaster and preliminarily explicated its possible physiological and molecular mechanisms. Our results indicated that the lethal time for 50% of female flies fed on HTE was significantly longer than that of male flies at the same heat stress temperature. Under thermal stress, the survival time of females was remarkably increased in the HTE addition groups compared to the non-addition group. Thermal hardening by acute exposure to 36°C for 30 min (9:00 to 9:30 a.m.) every day could significantly prolong the longevity of females. Without thermal hardening, HTE increased the antioxidant capacity of females under heat stress, accompanied by an increment of catalase (CAT) activity, and the inhibition for hydroxyl radicals (OH⋅) and superoxide anions (⋅O2–). Superoxide dismutase (SOD) activity and the inhibition for ⋅O2– was significantly affected by thermal hardening in the non-HTE addition groups, and significant differences were shown in CAT and SOD activities, and the inhibition for ⋅O2– among groups with thermal hardening. After heat exposure, heat shock protein 70 (Hsp70) was only up-regulated in the group with high levels of added HTE compared with the group without and this was similar in the thermal hardening group. It was concluded that the heat stress-relieving ability of HTE might be partly due to the enhancement of enzymatic activities of SOD and CAT, and the inhibition for OH⋅ and ⋅O2–. However, the expression levels of Hsp70 were not well related to thermal tolerance or heat survival.

A sulfated polysaccharide (SMP) from the Mesona chinensis Benth was successfully obtained and its immunomodulatory effects were evaluated. Results showed that SMP exhibited the proliferation effects in splenocytes in vitro and ameliorated the impaired of splenocytes in Cy-treated mice. SMP induced the production of nitric oxide (NO), interleukin (IL) −2, interferon-γ (IFN-γ), increased the expression of antioxidant enzymes (SOD and CAT), and reduced the production of malondialdehyde (MDA) in Cy-treated mice, as well as improved the blood index, body weight and organ index. In addition, SMP enhanced the viability of RAW264.7 macrophages and increased the secretion of IL-6, IL-1β and tumor necrosis factor-α (TNF-α) and production of NO in RAW264.7 cells. Furthermore, SMP binds to TLR4 (Toll-like Receptor 4) to promote RAW264.7 to produce cytokines, thereby exerting immunoregulatory function. These data indicated that SMP act a pivotal part in immunomodulatory and could be used as functional foods.