Lentinus squarrosulus (Mont.) mycelium enhanced antioxidant status in rat model

Lentinus squarrosulus Mont. Mushroom: Molecular Identification, In vitro Anti-Diabetic, Anti-Obesity, and Cytotoxicity Assessment

Objectives

Mushrooms are fungi with nutritional and health benefits. Lentinus squarrosulus Mont., an edible fungus, has traditional usage and relevance in local therapy for managing metabolic diseases. In that view, this study aimed to evaluate the in vitro anti-obesity, anti-diabetic, and cytotoxic potential of the chloroform/methanol extract (CME) and aqueous extract (AE) of the mushroom.

Materials and Methods

L. squarrosulus was identified using molecular biology tools. The CME and AE were obtained sequentially and, then, subjected to α-amylase, α-glucosidase, and lipase inhibitory enzyme assays as well as total phenolic content (TPC) and flavonoid content (TFC) estimations. The cytotoxic potential of extract fractions of L. squarrosulus was assessed using the brine shrimp lethality assay.

Results

The molecular identification of the mushroom displayed that the internal transcribed spacer sequence was an equivalent match to that of L. squarrosulus with a high percentage similarity, and thus assigned a unique accession number (KT120043.1). The CME of L. squarrosulus had higher TPC, TFC, and α-glucosidase inhibitory activity than AE. Furthermore, AE of the mushroom showed a higher lipase inhibitory potential with an IC₅₀ value of 22.28 ± 0.65 μg/mL than the CME, while that of the reference, i.e. orlistat was 2.28 ± 0.34 μg/mL. However, these extracts exhibited very low or no α-amylase inhibitory and cytotoxic activity at the tested concentrations.

Conclusion

This study reveals that CME of L. squarrosulus, rich in polyphenols and flavonoids, possesses considerable α-glucosidase and lipase inhibitory activities.

Functional composition and antioxidant property of crude polysaccharides from the fruiting bodies of Lentinus squarrosulus

Lentinus squarrosulus (Hed Khon Khao) is a source of bioactive polysaccharides. Three L. squarrosulus crude polysaccharides (LSPs) were subjected to cold water (LSP-CP), hot water (LSP-HP), and aqueous alkaline (LSP-AP) extractions, and their functional compositions and radical scavenging activities were compared. Synchrotron radiation FTIR (SR-FTIR) spectra and PCA plot analysis in the bio-regions (4000-400 cm^-1) revealed that functional composition LSPs differ significantly (P < 0.05). All LSPs had lipids, protein, and polysaccharides such as β-glucan. The major monosaccharides in LSP-CP and LSP-HP are d-galactose, d-glucose, and d-mannose at different proportions, while LSP-AP contained mainly d-glucose. Also, fucose and xylose were present in all the LSPs. LSP-CP, LSP-HP and LSP-AP induced maximum 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity of 78.93 ± 0.42% at 3 mg/mL, 79.16 ± 1.43% at 3 mg/mL and 65.26 ± 1.74% at 5 mg/mL, whiles on 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), their maximum activities were 98.94 ± 0.16% at 3 mg/mL, 97.42 ± 0.76% at 3 mg/mL and 47.24 ± 0.045% at 5 mg/mL, respectively. The results showed that LSP-CP and LSP-HP are good ABTS scavengers, whiles LSP-AP is poor ABTS scavenger. In overall, LSPs consist of essential functional compositions and could be used as natural antioxidants. This exploitation of fungal fruiting body extracts increased the potential use of L. squarrosulus in food and medicinal industries.

Toxicological Evaluation of Phytochemical Characterized Aqueous Extract of Wild Dried Lentinus squarrosulus (Mont.) Mushroom in Rats

Lentinus squarrosulus (Mont.) is an edible wild mushroom with tough fruiting body that belongs to the family Polyporaceae. It is used in ethnomedicine for the treatment of ulcer, anaemia, cough and fever. Recent studies have demonstrated its anticancer, anti-diabetic and antioxidant properties. However, little or no information is available regarding the bioactive components and toxicological study of wild dried L. squarrosulus. Therefore, this study investigated the bioactive components of aqueous extract of boiled wild dried L. squarrosulus and its toxicological effects in rats. The extract of L. squarrosulus was subjected to GC-MS analysis. The acute toxicity test was performed by oral administration of a single dose of up to 5,000 mg/kg extract of L. squarrosulus. In subacute study, the rats were orally administered extract of L. squarrosulus at the doses of 500, 1,000 and 1,500 mg/kg body weight daily for 14 days. The haematological, lipid profile, liver and kidney function parameters were determined and the histopathology of the liver and kidney were examined. The GC-MS analysis revealed the presence of bioactive compounds; 1-tetradecene, fumaric acid, monochloride, 6-ethyloct-3-yl ester, 9-eicosene, phytol, octahydropyrrolo[1,2-a]pyrazine and 3-trifluoroacetoxypentadecane. In acute toxicity study, neither death nor toxicity sign was recorded. In the sub-acute toxicity study, significant differences (p < 0.05) were observed on creatinine, aspartate aminotransferase, alanine aminotransferase, total cholesterol, triglycerides and high-density lipoprotein cholesterol. Whilst no significant differences (p > 0.05) were observed on packed cell volume, heamoglobin, red blood cell, white blood cell and alkaline phosphatase, in all the tested doses. No histopathological alterations were recorded. Our findings revealed that aqueous extract of L. squarrosulus may have antimicrobial, antinocieptive and antioxidant properties based on the result of GC-MS analysis. Results of the toxicity test showed no deleterious effect at the tested doses, suggesting that L. squarrosulus is safe for consumption at the tested doses.