Xylan is the second most abundant naturally occurring renewable polysaccharide available on earth. It is a complex heteropolysaccharide consisting of different monosaccharides such as l-arabinose, d-galactose, d-mannoses and organic acids such as acetic acid, ferulic acid, glucuronic acid interwoven together with help of glycosidic and ester bonds. The breakdown of xylan is restricted due to its heterogeneous nature and it can be overcome by xylanases which are capable of cleaving the heterogeneous β-1,4-glycoside linkage. Xylanases are abundantly present in nature (e.g., molluscs, insects and microorganisms) and several microorganisms such as bacteria, fungi, yeast, and algae are used extensively for its production. Microbial xylanases show varying substrate specificities and biochemical properties which makes it suitable for various applications in industrial and biotechnological sectors. The suitability of xylanases for its application in food and feed, paper and pulp, textile, pharmaceuticals, and lignocellulosic biorefinery has led to an increase in demand of xylanases globally. The present review gives an insight of using microbial xylanases as an "Emerging Green Tool" along with its current status and future prospective.
Endophytic actinobacteria play an important role in growth promotion and development of host plant by producing enormous quantities of novel bioactive natural products. In the present investigation, 169 endophytic actinobacteria were isolated from endospheric tissues of Rhynchotoechum ellipticum. Based on their antimicrobial potential, 81 strains were identified by 16rRNA gene analysis, which were taxonomically grouped into 15 genera. All identified strains were screened for their plant growth promoting attributes and, for the presence of modular polyketide synthases (PKSI, PKSII and nonribosomal peptide synthetase (NRPS) gene clusters to correlate the biosynthetic genes with their functional properties. Expression studies and antioxidant potential for four representative strains were evaluated using qRT-PCR and DPPH assay respectively. Additionally, six antibiotics (erythromycin, ketoconazole, fluconazole, chloramphenicol, rifampicin and miconazole) and nine phenolic compounds (catechin, kaempferol, chebulagic acid, chlorogenic acid, Asiatic acid, ferulic acid, arjunic acid, gallic acid and boswellic acid) were detected and quantified using UHPLC-QqQLIT-MS/MS. Furthermore, three strains (BPSAC77, 121 and 101) showed the presence of the anticancerous compound paclitaxel which was reported for the first time from endophytic actinobacteria. This study provides a holistic picture, that endophytic actinobacteria are rich bacterial resource for bioactive natural products, which has a great prospective in agriculture and pharmaceutical industries.
Diets containing high proportions of fruits and vegetables reduce the risk of onset of chronic diseases. The role of herbal medicines in improving human health is gaining popularity over the years, which also increases the need for safety and efficiency of these products. Green leafy vegetables (GLVs) are the richest source of phenolic compounds with excellent antioxidant properties. Increased consumption of diets containing phenolic compounds may give positive and better results to human health and significantly improves the immune system. Highly selective, susceptible and versatile analytical techniques are necessary for extraction, identification, and quantification of phenolic compounds from plant extracts, which helps to utilize their important biological properties. Recent advances in the pre-treatment procedures, separation techniques and spectrometry methods are used for qualitative and quantitative analysis of phenolic compounds. The online coupling of liquid chromatography with mass spectrometry (LC–MS) has become a useful tool in the metabolic profiling of plant samples. In this review, the separation and identification of phenolic acids and flavonoids from GLVs by LC–MS have been discussed along with the general extraction procedures and other sources of mass spectrometer used. The review is devoted to the understanding of the structural configuration, nature and accumulation pattern of phenolic acids and flavonoids in plants and to highlighting the recent developments in the chemical investigation of these compounds by chromatographic and spectroscopic techniques. It concludes with the advantages of the combination of these two methods and prospects.
Plants have been used since ancient times as an important source of biologically active substances. The aim of the present study was to investigate the phytochemical constituents (flavonoids and phenolics), antioxidant potential, cytotoxicity against HepG2 (human hepato carcinoma) cancer cell lines, and the antimicrobial activity of the methanol extract of selected traditional medicinal plants collected from Mizoram, India. A number of phenolic compounds were detected using HPLC-DAD-ESI-TOF-MS, mainly Luteolin, Kaempferol, Myricetin, Gallic Acid, Quercetin and Rutin, some of which have been described for the first time in the selected plants. The total phenolic and flavonoid contents showed high variation ranging from 4.44 to 181.91 μg of Gallic Acid equivalent per milligram DW (GAE/mg DW) and 3.17 to 102.2 μg of Quercetin/mg, respectively. The antioxidant capacity was determined by DPPH (IC50 values ranges from 34.22 to 131.4 μg/mL), ABTS (IC50 values ranges from 24.08 to 513.4 μg/mL), and reducing power assays. Antimicrobial activity was assayed against gram positive (Staphylococcus aureus), gram negative (Escherichia coli, Pseudomonas aeruginosa), and yeast (Candida albicans) demonstrating that the methanol extracts of some plants were efficacious antimicrobial agents. Additionally, cytotoxicity was assessed on human hepato carcinoma (HepG2) cancer cell lines and found that the extracts of Albizia lebbeck, Dillenia indica, and Bombax ceiba significantly decreased the cell viability at low concentrations with IC50 values of 24.03, 25.09, and 29.66 μg/mL, respectively. This is the first report of detection of phenolic compounds along with antimicrobial, antioxidant and cytotoxic potential of selected medicinal plants from India, which indicates that these plants might be valuable source for human and animal health.
The genus Streptomyces under phylum actinobacteria has been recognized as a prolific source for the production of bioactive secondary metabolites. An actinobacterial strain designated as DST103 isolated from a wetland fresh water sediment of Tamdil Lake, Mizoram, Northeast, India was identified as Streptomyces cyaneofuscatus (KY287599) using 16SrRNA gene sequencing which shares 99.87% sequence similarity with Streptomyces cyaneofuscatus NRRL B-2570T. The strain showed broad spectrum antimicrobial activities against Gram negative bacteria (Escherichia coli MTCC 739 and Pseudomonas aeruginosa MTCC 2453), Gram positive bacteria (Micrococcus luteus NCIM 2170 and Staphylococcus aureus MTCC 96) and yeast pathogen Candida albicans MTCC 3017). The methanolic extract of the strain DST103 exhibited highest antimicrobial activity against E. coli (IC50 = 2.10 μg/mL) and minimum activity against S. aureus (IC50 = 43.63 μg/mL). Five antibiotics [trimethoprim (18 μg/g), fluconazole (6 μg/g), ketoconazole (18 μg/g), nalidixic acid (135 μg/g), and rifampicin (56 μg/g)] were detected and quantified using ultra-performance liquid chromatography (UPLC-ESI-MS/MS). Further, biosynthetic potential genes [polyketide synthases type II, non-ribosomal peptide synthetases, and aminodeoxyisochorismate synthase (phzE)] were also detected in strain DST103 which may possibly be responsible for the production of antimicrobial compounds. Additionally, gas chromatography-mass spectrometry analysis showed the presence of four volatile compounds which might be responsible for their diverse biological activity. The present study revealed the presence of bioactive compounds in strain DST103, which may be a promising resource for the discovery of novel bioactive metabolites against wide range of pathogens.
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