Phenolic and flavonoid contents and antioxidant activity of an endophytic fungus Nigrospora sphaerica (EHL2), inhabiting the medicinal plant Euphorbia hirta (dudhi) L.

Abstract

Graphical abstract Since endophytic fungi are pivotal sources of various bioactive natural compounds, the present study is aimed to investigate the antioxidant compounds of the endophytic fungus Nigrospora sphaerica isolated from a pantropical weed, Euphorbia hirta L. The fungus was fermented in four different media and each filtered broth was sequentially extracted in various solvents. Crude extracts collected from different solvents were subjected to phytochemical analysis and antioxidant activity. The total phenolic content (TPC) and total flavonoid content (TFC) were maximal in ethyl acetate crude extract (EtOAcE) of endophyte fermented in potato dextrose broth (PDB) medium (77.74 ± 0.046mgGAE/g and 230.59 ± 2.0 mgRE/g) with the highest 96.80% antioxidant activity. However, TPC and TFC were absent in hexane extract of Czapek Dox broth (CDB) medium exhibiting the lowest 4.63 ± 2.75% activity. The EtOAcE (PDB) showed a positive correlation between TFC and antiradical activity ( R 2 = 0.762; P < 0.05), whereas a high positive correlation was noticed between TPC and antioxidant activity ( R 2 = 0.989; P < 0.05). Furthermore, to determine the antioxidant activity, EtOAcE (PDB) was subjected to TLC bioautography-based partial purification, while GC/MS analysis of the partial purified extract was done to confirm the presence of phenolics along with antioxidant compounds that resulted in the detection of 2,4-Di-tert-butylphenol (13.83%), a phenolic compound accountable for the antioxidant potential. Conclusively, N. sphaerica is a potential candidate for natural antioxidant. Supplementary Information The online version contains supplementary material available at 10.1007/s00203-021-02650-7.

Distribution, cytotoxicity, and antioxidant activity of fungal endophytes isolated from Tsuga chinensis (Franch.) Pritz. in Ha Giang province, Vietnam

“…Similar findings have been shown in fungi recovered from some medicinal plants including C. roseus, E. hirta, Conyza blini H.Lév (Dhayanithy et al 2019;Tang et al 2020;Gautam et al 2022). The best DPPH and superoxide radical scavenging capacities observed in fungal extracts may be attributed to their hydrogen-donating ability and superoxide dismutase-like properties, respectively indicating the potent wide-ranging antioxidant activities.…”

“…Endophytic fungi that have been exploited in many medicinal and herb plants such as Passiflora incarnata (L.) Medik, Catharanthus roseus (L.) G. Don, Euphorbia hirta L., and Taxus chinensis (Pilg.) Rehder has been considered as producers of actively plant-derived compounds that belong to different structural groups including phenols, flavonoids, alkaloids, steroids, and terpenoids (Zhou et al 2007;Dhayanithy et al 2019;da Silva et al 2020;Gautam et al 2022). Notably, the capability to produce host-specific metabolites, vincristine, vinblastine, camptothecin, podophyllotoxin, and the billion-dollar anti-cancer drug paclitaxel has been reported in fungal endophytes (Tang et al 2020;Hridoy et al 2022).…”

Bioactive compounds and biomedical applications of endophytic fungi: a recent review

“…Furthermore, endophytic Diaporthe have been reported for antioxidant activity [ 263 ]. Epicoccum and Nigrospora genera have potential antioxidant activity as E. nigrum [ 240 ], N. sphaerica [ 237 ] and N. oryzae [ 238 ]. Moreover, endophytic Colletotrichum sp.…”

Chemical profile and antioxidant activity of bidirectional metabolites from Tremella fuciformis and Acanthopanax trifoliatus as assessed using response surface methodology

“…Total flavonoid content was determined according to the protocol described in Gautam et al ( 29 ) with minor modifications. In brief, 1 mL of fermentation supernatant and 150 μL of sodium nitrite 5% (v/v) were added to a 5-mL test tube.…”