MOLECULAR IDENTIFICATION AND ASSESSMENT OF SOME NUTRACEUTICAL POTENTIALS OF A WILD MACROFUNGUS, LENZITES QUERCINA (L.) KARSTEN

Abstract

The nutraceutical property of a wild macrofungus, Lenzites quercina collected from Akure were assessed. Identification of L. quercina was carried out using both the morphological and molecular characteristics. The effect of fermentation on the proximate composition, minerals, amino acids, fatty acids and phytochemical contents of L. quercina were determined using standard methods. Antimicrobial efficacy of the extracts from raw and fermented L. quercina was tested against typed cultures, clinical isolates and microorganisms isolated from street foods. The scavenging potentials, anticancer activity and safety of L. quercina extracts were also evaluated. Basic local alignment search tool (BLAST) on NCBI GenBank revealed that Lenzites species from Nigeria is closely related to L. quercina (100 %) with accession number of JF689829.1. The result of proximate composition revealed higher protein content (26.15%) in fermented sample, while the value of carbohydrate (38.3%), crude fibre (27.6%) and ash content (6.5%) were higher in raw sample (P<0.05). The macro and micro elements in the raw and fermented L. quercina were in decreasing order of Ca > K > Zn > Fe > Na > Mg > Pb > Cu with values ranging from 8.43 mg/g to 721.6 mg/g. The content of iron (51.94 mg/kg) and zinc (91.90 mg/kg) increased in fermented L. quercina and was significantly different (P < 0.05) from the raw sample of L. quercina. The amino acids in raw and fermented L. quercina ranged from 0.05 mg/g to 12.93 mg/g. Essential amino acids such as isoleucine, leucine, lysine, tyrosine, tryptophan and valine increased in fermented sample with values of 3.57 mg/g, 8.83 mg/g, 5.90 mg/g, 2.05 mg/g, 3.70 mg/g and 5.04 mg/g respectively. Fatty acids in raw and fermented L. quercina ranged from 0.11 % to 38.5 %. Essential fatty acids; linoleic (12.48%) and linolenic (22.50%) in fermented L. quercina increased and was significantly different (P< 0.05) from raw L. quercina. This study revealed the presence of phenol, flavonoids, saponins and cardiac glycosides in all the extracts. Ethyl acetate extract of fermented L. quercina (FEA) has higher phenolic content of 67.6 mg gallic acid equivalent (GAE)/g extract, while ethyl acetate extract of raw L. quercina (REA) has the highest flavonoid of 51.4 mg quercetin equivalent (QE)/g extract. The level of alkaloids in the extracts ranged from 14.4 to 20.7 mg/g, while steroids, saponins and terpenoids ranged from 6.1 to 12.8 mg/g, 4.5 to 10.6 mg/g and 2.8 to 17.2 mg/g respectively. The structural elucidation of the bioactive compounds from the extracts revealed the presence of following: caprylic acid, tetradecanoic acid, methyl-11-octadecanote, stearic acid, oleic acid and 4-methyl-2-propyl-1-pentanol. L. quercina extracts exhibited antimicrobial property against tested isolates with inhibitory zones ranging from 4.0 mm to 18.0 mm. The purified fractions from L. quercina exhibited better inhibitory zones of 5.0 mm to 26.0 mm and fungal mycelia inhibition of 20.3% to 66.3% against tested bacteria and fungi respectively. The scavenging activity of extracts against free radicals of 1, 1-diphenyl-2-picrylhydrazyl (DPPH), ferrous ion, nitric oxide and thiobarbituric acid reactive species (TBARS) production ranged from 27.7% to 99.3% with IC50 value of 0.34 to 1.80 mg/ml. Extracts of L. quercina exhibited pronounced cytotoxicity effect of 24.6% to 89.6% against human cervical cancer (HeLa), rhabdomyosarcoma (RD) and African green monkey kidney (VERO) cell lines with the CC50 ranging from 0.11 to 3.32 𝜇g/ml. The lethal concentration of the extract that killed 50 % (LC50) of Artemia salina larvae was within 28.6 to 245.5 𝜇g/ml. This study revealed that extracts of L. quercina contain some bioactive compounds with effective antimicrobial, antioxidant and anticancer properties. Therefore, the identified bioactive compounds could be exploited by biopharmaceutical and other allied industries for therapeutic uses