Wild Edible Underutilized Plants by Mohan V. R.; Tresina P. S.; Doss A

Wild Edible Underutilized Plants by Mohan V. R.; Tresina P. S.; Doss A

Author:Mohan, V. R.; Tresina, P. S.; Doss, A.
Language: eng
Format: epub
Publisher: Apple Academic Press, Incorporated
Published: 2020-07-12T16:00:00+00:00


6.4.3 IMMUNOMODULATORY ACTIVITIES

Purified dioscorin from yam tubers proved immune-modulatory activities in vitro. The effects of dioscorin on native BALB/c mice spleen cell proliferation were assessed by MTT assay. It was found that dioscorin stimulated RAW 264.7 cells to produce nitric oxide (NO), in the absence of lipopolysaccharide (LPS) pollution. Yam dioscorin exhibited immunemodulatory activities by the innate immunity which is a nonspecific immune system. This comprises the cells and mechanisms that defend the host from infection by other organisms in a nonspecific manner. Dioscorin was reported to stimulate cytokine production and to enhance phagocytosis. Additionally, the released cytokines may act synergistically with phytohemagglutinin (PHA) which is a lectin found in plants that stimulate the proliferation of splenocytes (Liu et al., 2007).

Quite a lot of readings have demonstrated the immune activity of yam mucopolysaccharides (YMP). In vitro cytotoxic activity of mouse splenocyte against leukemia cell was increased in the presence of YMP of Dioscorea batatas at 10 g/mL. Also the production of IFN- was radically increased in the YMP treated splenocytes, suggesting their capability of inducing cell-mediated immune responses. In addition, YMP at a concentration of 50 g/mL boosted up the uptaking capacity and lysosomal phosphatase activity of peritoneal macrophages (Choi et al., 2004).

Dioscorea phytocompounds developed murine splenocyte proliferation ex vivo and advanced regeneration of bone marrow cells in vivo. Mice which were fed with a Dioscorea extract recovered damaged bone marrow progenitor cell populations that had been exhausted by large doses of 5-fluorouracil (5-FU). Moreover, they reported that the phytocompound(s) responsible for these bioactivities had a high molecular weight (≥100 kDa) and were most likely polysaccharides. They postulated those high-molecular-weight polysaccharides in DsCE-II act on specific target cell types in the GI tract (dendritic cells, intestinal epithelial cells, and T-cells) to arbitrate a cascade of immunoregulatory activities leading to the recovery of damaged cell populations following 5-FU or other chemical insults in the bone marrow, spleen, or other immune cell systems (Su et al., 2011).

Dioscorea tuber mucilage from Taiwanese yams (Dioscorea japonica) showed significant effects on the innate immunity and adaptive immunity on BALB/c mice through oral administration. As well, it was found that the specific antibodies rapidly responded against foreign proteins (or antigens) in the presence of yam mucilage. Mucilage from these yam varieties showed signs of a stimulatory effect on phagocytic activity by granulocyte and monocyte (ex vivo), on peritoneal macrophages, and on the RAW 264.7 cells (in vivo) of mice (Shang et al., 2007).

Yams (Dioscorea esculenta) showed anti-inflammatory activity on carrageenan-induced edema in the right hind paw of Wistar rats. However, this activity was short lived as it was quickly removed from the system after reaching the peak within 2 hours. Phytochemical screening of D. esculenta substantiated the presence of saponins, sitosterol, stigmasterol, cardiac glycosides, fats, starch, and diosgenin, which could be responsible for the observed activity (Olayemi and Ajaiyeoba, 2007). Diosgenin contained in Chinese yam was an immunoactive steroidal saponin which also showed a prebiotic effect. Diosgenin had also beneficial effects on the growth of enteric lactic acid bacteria (Chen et al.



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