Antioxidant activity of exo‐metabolites produced by Fusarium oxysporum: An endophytic fungus isolated from leaves of Otoba gracilipes

Abstract

Tropical ecosystems hold an extremely diverse array of endophytic fungi, but their potential use still remains to be explored. In this study, we isolated an endophytic fungus from the leaves of Otoba gracilipes, a medicinal tree from a tropical rainforest in Colombia. Following isolation and cultivation, we evaluated its extracellular crude extract for antioxidant activity. Using traditional and molecular methods (ITS1, NL1 regions), the endophyte was identified as Fusarium oxysporum. Fresh spores from the fungal isolate were inoculated in liquid media (potato dextrose broth [PDB] and potato dextrose–yeast extract broth [PDYB]) and centrifuged for recovering extracellular polysaccharides from the exhausted medium after 30 days of cultivation. Crude extracts were recovered, purified, lyophilized, and evaluated for their ability to inactivate the free radical 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH). The extracts obtained from PDB culture media had a 51.5% of scavenging effect on DPPH after 5 min of reaction compared with the extracts from PDBY (26.4%), which suggests a high antioxidant potential of these fungal extracts. Thus, our results suggest other fungi from tropical ecosystems should be explored as potential sources of novel enzymes and other metabolites with bioactivity.

Neurosporaxanthin Overproduction by Fusarium fujikuroi and Evaluation of Its Antioxidant Properties

“…Altogether, data reveal that SG39 extracts have substantially higher antioxidant capacity than SG256 extracts, both considering their quenching activity against [O 2 ( 1 Δ g )] in organic solvent, and their scavenging activity against different free radicals in aqueous solution and in liposomes ( Figure 4 and Figure 5 ). Since carotenoids were essentially absent in SG256 strain ( Figure 3 b), the baseline antioxidant activity detected in SG256 may be attributed to other non-carotenoid components in the fungus biomass, such as flavonoids, α,γ-tocopherols, ascorbic acid, and even exopolysaccharides [ 51 ]. Although SG39 strain also contains those antioxidants, the substantial accumulation of NX in SG39 (with minor contribution of other carotenoids) may account for its remarkable antioxidant capacity compared to SG256.…”

Biocatalytic Potential of Native Basidiomycetes from Colombia for Flavour/Aroma Production

“…Basidiomycetes strains were obtained from basidiomas collected in the tropical forests of Colombia in Antioquia and Valle del Cauca. The strains of the endophytic fungus were isolated from the leaves of Otoba gracilipes (Myristicaceae) that were collected in Valle del Cauca [ 73 ]. Briefly, sections of the fresh basidiomas were cleaned with a series of sequential washing steps for one min each as follows: Tween 80 (0.01%), sterile water, 70% ethanol, sterile water, 70% ethanol, and lastly, another round of sterile water.…”

Differences in Production, Composition, and Antioxidant Activities of Exopolymeric Substances (EPS) Obtained from Cultures of Endophytic Fusarium culmorum Strains with Different Effects on Cereals

“…Similar correlation coefficient values were calculated for the standard antioxidant substances: vitamin C and Trolox. Crude extract obtained from PDB culture of F. oxysporum isolated from Otoba gracilipes leaves was characterised by an over 50% of scavenging effect on DPPH [43]. All filtrates of cultures of 49 endophytic strains, including 18 from the Fusarium genus and 5 from the Nectria genus (Fusarium teleomorph), isolated from Fritillaria unibracteata displayed antioxidant activity, and significant positive correlations were found between total phenolic content (TPC) and antioxidant capacities (DPPH and ABTS) [89].…”

“…Crude extract obtained from PDB culture of F. oxysporum isolated from Otoba gracilipes leaves was characterised by an over 50% of scavenging effect on DPPH [43].…”