Characterization and evaluation of mycosterol secreted from endophytic strain of Gymnema sylvestre for inhibition of α-glucosidase activity

Abstract

Endophytic fungi produce various types of chemicals for establishment of niche within the host plant. Due to symbiotic association, they secrete pharmaceutically important bioactive compounds and enzyme inhibitors. In this research article, we have explored the potent α-glucosidse inhibitor (AGI) produced from Fusarium equiseti recovered from the leaf of Gymnema sylvestre through bioassay-guided fraction. This study investigated the biodiversity, phylogeny, antioxidant activity and α-glucosidse inhibition of endophytic fungi isolated from Gymnema sylvestre. A total of 32 isolates obtained were grouped into 16 genera, according to their morphology of colony and spores. A high biodiversity of endophytic fungi were observed in G. sylvestre with diversity indices. Endophytic fungal strain Fusarium equiseti was identified through DNA sequencing and the sequence was deposited in GenBank database (https://ncbi.nim.nih.gov) with acession number: MF403109. The characterization of potent compound was done by FTIR, LC-ESI-MS and NMR spectroscopic analysis with IUPAC name 17-(5-ethyl-6-methylheptan-2-yl)-10,13-dimethyl-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro-1H-cyclopenta[a] phenanthren-3-ol. The isolated bioactive compound showed significant α-amylase and α-glucosidase inhibition activity with IC50 values, 4.22 ± 0.0005 µg/mL and 69.72 ± 0.001 µg/mL while IC50 values of acarbose was 5.75 ± 0.007 and 55.29 ± 0.0005 µg/mL respectively. This result is higher in comparison to other previous study. The enzyme kinetics study revealed that bioactive compound was competitive inhibitor for α-amylase and α-glucosidase. In-silico study showed that bioactive compound binds to the binding site of α-amylase, similar to that of acarbose but with higher affinity. The study highlights the importance of endophytic fungi as an alternative source of AGI (α-glucosidase inhibition) to control the diabetic condition in vitro.

Bioprospecting of fungal endophytes from Oroxylum indicum (L.) Kurz with antioxidant and cytotoxic activity

“…The leaf samples were washed under running tap water followed by deionized water and surface disinfection was done by following standard method with minor modifications [ 7 , 19 ]. Briefly, the leaf samples were immersed in 70% ethanol for 1 minute, then in 0.1% sodium hypochlorite (NaOCl; Biochem, India) for 1 minute, dipped in 70% ethanol for 1 minute followed by washing with distilled water twice for 1 minute.…”

“…Among endophytic microbial species, fungal endophyte shows asymptomatic relationship with plant and have ability to mimic the bioactive compounds similar to their host plant. Bioactive compounds derived from fungal endophytes are of great significance and used in drug discovery and development, food industry and agriculture [ 5 – 7 ]. In order to preserve the biodiversity and ethnopharmacological significance of medicinal plants, fungal endophytes are explored for an alternative source for the extraction of pharmacologically significant bioactive compounds.…”

Plant associated fungal endophytes as a source of natural bioactive compounds

“…Results of the anti-diabetic assay revealed that the compound has a potential to inhibit αglucosidase from Saccharomyces cerevisiae with an IC 50 value of 41.75 μg/mL (Indrianingsih and Tachibana 2017). In one of the recent report from our lab, antidiabetic activity of the mycosterol derived from fungal endophyte Fusarium equiseti associated with the host plant Gymnema sylvestre show competitive inhibition against α-glucosidase and α-amylase (Ranjan et al 2019).…”

Ascodesmis rosicola sp. nov. and Talaromyces rosarhiza sp. nov., two endophytes from Rosa roxburghii in China

“…All materials were sent to the laboratory immediately and stored in a refrigerator at 4°C. Each sample tissue was examined within 48 hours of collection ( Ranjan et al 2019 ).…”

“…These plates were incubated at 28±1°C in a 12-h light:12-h dark photoperiod for 3 to 7 days. After several days, hyphal tips were subcultured into fresh PDA plates to obtain pure endophytic strains ( Ranjan et al 2019 ).…”