Phytochemical screening and antioxidative property evaluation of lipid-producing fungi.

The increased demands for natural bioactive compounds have induced the search for unusual sources. Microorganisms, especially fungi are a potent source of secondary metabolites, which could act mainly as antioxidant compounds to prevent oxidative stress. In the present study three soil-isolated fungi Aspergillus niger, Aspergillus heteromorphus and Aspergillus fumigatus, were screened for their oleaginous property as well as their potential for the production of bioactive compounds. Fungal biomasses were freeze dried and extracted with methanol using a cold percolation process for the production of intracellular metabolites and the fungal culture media after fermentation were examined for extracellular metabolites. Intracellular and extracellular extracts of the isolated fungi along with the single-cell oils extracted from those fungi were screened for phytochemicals, which showed the presence of alkaloids, flavonoides, glycosides, phenols, saponins and terpenoids. All strains showed potent antioxidant activity, determined using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid (ABTS) and ferric reducing antioxidant power (FRAP) activity. Extracellular extract and single-cell oil of A. heteromorphus showed the highest antioxidant activity with maximum ABTS radical scavenging activity and reducing potential. Highest content of phenolic and flavonoid compounds within the isolated fungi was found to be 37.58 mg gallic acid equivalent (GAE)/g and 62.07 mg catechine equivalent (CE)/g, respectively. Chromatographic analysis of the intracellular and extracellular extracts of the fungi showed the presence of gallic acid, di-hydroxy benzoic acid, ferulic acid, quercetin, epigerin, kampferol, trans cinnamic acid, chlorogenic acid and rutin, which made them biologically important and beneficial for human health.

Phytochemical screening and antioxidant and antimicrobial activities of crude extracts of different filamentous fungi.

Five filamentous fungal strains that grew in different whey-based media under submerged fermentation were investigated for antioxidant properties and phytochemicals. Phytochemical analysis revealed the presence of alkaloids, tannin, flavonoids, glycosides, phenols, saponins, and terpenes in the crude intra- and extracellular ethyl acetate extracts of different strains. All fungal extracts exhibited effective antioxidant activities in terms of TPC, TFC, DPPH, FRAP, ABTS, reducing power, and metal chelating capacity. The activities of intracellular extracts were higher than the extracellular metabolites. Fermentation media with sugar and salt supplementation significantly influenced antioxidant production. Aspergillus niger in glucose-supplemented whey medium was found to exhibit the highest antioxidant properties. The antimicrobial activity of A. niger and Penicillium expansum extracts by microtiter plate assay showed a promising result against some pathogenic bacterial strains. Chromatographic analysis of the fungal extracts revealed the presence of chlorogenic acid, trans-cinnamic acid, ferulic acid quercetin, myricetin, kaempferol, and catechin which are known for their antioxidant properties. Accumulation of nutrients in fungal biomass under constraint environment produces secondary metabolites which has demonstrated efficacy towards alleviation of several degenerative diseases. The antioxidative enriched phytochemicals present in these five different fungal strains will provide a breakthrough in the utilisation of whey as inexpensive source of substrate for the growth of these fungi. Moreover, phytochemicals could be utilized as therapeutic agents in a cost-effective and environmentally friendly manner.

Evaluation of nutraceutical application of xylooligosaccharide enzymatically produced from cauliflower stalk for its value addition through a sustainable approach.

There is increasing attention on the exploration of waste feedstocks as economically viable substrates for the production of prebiotic oligosaccharides, especially xylooligosaccharides, as excellent candidates for the maintenance and promotion of gut microbiota. XOS, an emerging prebiotic that has several functional attributes and beneficial health effects, is mainly produced by different processes, especially enzymatic hydrolysis through the valorisation of xylan enriched lignocellulosic materials. The present study deals with the enzymatic production of xylooligosaccharide (XOS) from xylan rich cauliflower stalk, a novel source. Delignification with alkali (NaOH) was found to be more efficient than acid and autohydrolysis, resulting in a higher extraction yield of xylan (18.42%). Alkaline extraction for 120 minutes at 1.25 M alkali concentration produced maximum xylan yield. FTIR analysis of xylan extracted from cauliflower stalk by an alkaline (NaOH) pretreatment method showed typical absorption bands at 1729 cm-1 that correspond to acetyl groups exhibiting the typical xylan specific band. Enzymatic hydrolysis was carried out with indigenously produced crude endoxylanase obtained from Aspergillus niger MTCC 9687 and the effects of substrate concentration, enzyme concentration, pH, time and temperature were investigated. High resolution MS analysis showed the presence of xylobiose as the major XOS. The major 1H spectral signals of XOS liberated from enzymatically hydrolysed alkali extracted cauliflower stalk xylan showed the presence of ß-anomeric protons in the spectral region of 4.0-4.7 ppm. Prebiotic efficacy of cauliflower stalk derived XOS alone and synbiotic combinations with known probiotic strains (Lactiplantibacillus plantarum, Bifidobacterium bifidum, Lactobacillus delbrueckii ssp. Helveticus) were evaluated. Butyrate was found to be the major short chain fatty acid produced by XOS supplemented fermentation media. All the synbiotic combinations showed significantly higher antioxidant and antimicrobial activities and reduced the viability of human bone cancer MG-63 cells. The individual profiles of antimicrobial components of XOS were identified as dihydroxy benzoic acid and aspartic acid by HPLC coupled to a photodiode array detector.