**3. Antidiabetic activity of mushroom biomolecules**

Mushrooms are fungi that either grow above or below the ground. These are the macro fungi that can be easily seen with the naked eye. Mushrooms have been used since ancient times by the people of India and China or their medicinal properties. Nowadays many countries are consuming mushrooms for not only their unique flavor but also for their culinary effects. As many studies have revealed that mushrooms are rich sources of: proteins, carbohydrates, vitamins (B1, B2, B12, C, D, and E) and minerals like Mn, Mg, Se, Ca, Na, Cu, K, and Fe [38]. These nutritional factors in mushrooms have made it very efficient to fight diabetes. In vitro and in vivo studies have shown that the extract of mushrooms can reduce the expression of proinflammatory cytokines, induced by lipopolysaccharides which further improved the glucose uptake in skeletal muscle cell lines [39].

One of the most active biomolecules of mushrooms is β-glucans, a polysaccharide that can protect the pancreatic tissue from damage and restore the function of b-cells which helps to lower the blood glucose levels [40]. The low energy, lack of cholesterol and fats, less carbohydrates, and high minerals, proteins and vitamins made mushrooms an ideal food for diabetic patients. The consumption of mushrooms for a few days only can help to manage the low-density lipoproteins, total cholesterol, high-density lipoprotein, triglycerides levels in serum [10]. Besides bioactive molecules, mushrooms are very good in antioxidants activity and are also a good source of dietary fibers and water. Some of the most culinary properties containing mushrooms are *Agaricus bisporus, Agaricus subrufescens, Cordyceps millitaris, Cordyceps sinensis, Grifola frondosa, Ganoderma lucidum, Phellinus linteus, Pleurotus flabellatus, Pleurotus citrinopileatus, Pleurotus ostreatus, Poria cocos* [10, 41]. Extracts of Ganoderma lucidum contain: polysaccharides, triterpenoids, proteoglycans, and proteins which have been shown to reduce blood glucose levels. The proteoglycans of *G. lucidum* inhibit the tyrosine phosphatase 1B protein in diabetic patients. *G. lucidum* has proven to be very effective in controlling diabetes. Moreover, the triterpenoid from *G. lucidum* inhibits the aldose reductase and a-glucosidase enzymes which are responsible for the elevation of postprandial glucose levels [42]. Polysaccharides from *G. atrum* (PSG-1) increase insulin sensitivity and lower the serum lipid by increasing and decreasing the expression levels of Bcl-2 and Bax, respectively in pancreatic cells [43].

### *Mushroom; Chemistry, Bioactive Components, and Application DOI: http://dx.doi.org/10.5772/intechopen.104182*

Heteropolysaccharides are one of the bioactive molecules of Pleurotus ostreatus that control diabetes by activating the Glycogen synthase kinase 3 (GSK3) by phosphorylation and facilitating the translocation of glucose transporter type 4 (GLUT4) in streptozotocininduced diabetic rats [44]. *Lentinula edodes* promote the growth of gut microbiota, which play a very important role to balance the energy in diabetic patients. Another mushroom, *Hirsutellas inensis* shows antidiabetic, antiobesogenic effects in high-fat-diet feed-mice by modification of the components of gut microbiota. The polysaccharides and fibers of mushrooms act as prebiotics that helps in the treatment of diabetic patients [45]. Recently, researchers have found the potential effects of mushrooms in diabetic nephropathy conditions. Polysaccharides from Auricularia auricula are very helpful in promoting the oxidation of glucose. This polysaccharide protects against diabetic nephropathy by the regulation of creatinine, inflammatory factors, blood urea nitrogen, and urine protein. Polysaccharides isolated from *Flammulina velutipes* provided protection against reactive oxygen species (ROS) and reduced the level of malondialdehyde (MDA) in the kidney. The studies have also revealed that the proteoglycans from Ganoderma lucidum can restore kidney function by providing antioxidant activity [46]. According to a study conducted by Chou, Kan, Chang, Peng, Wang, Yu, Cheng, Jhang, Liu and Chuu [47], low molecular weight polysaccharide of *Inonotus obiquus* (LIOP) significantly reduces the expression of NF-jB and Transforming growth factor-beta (TGF-b) in a dosedependent manner [48]. They find that LIOP treatment can improve glucolipotoxicity induced renal fibrosis in diabetic nephropathy mice. *Hypsizigusm armoreus* have been used to examine its protective effect on the liver, kidney, and pancreas. The spent mushroom compost polysaccharide (SCP), its enzymatic lysates (ESCP), and acidbased hydrolyzed SCP (ASCP) were tested in streptozotocin-induced mice and found that it increased the: catalase, superoxide dismutase, and glutathione peroxidase activity whereas, it reduced the lipid peroxide and malonaldehyde levels [49]. a-glucosidase inhibiting polysaccharide (ePS-F4-1) with triterpenoids had been purified from Coriolus versicolor. Another bioactive molecule, MT-a-glucan (polysaccharide) from Grifola frondosa increases the expression of Interleukin-2 (IL-2) and prevents the injury of b-cells [50]. Submerged cultured mycelium of Agaricus brasiliensis and *G. lucidum* has shown a protective effect on red blood cells (RBCs) in Streptozotocin (STZ)-induced diabetic rats [51].
