Phylogenetic diversity and antioxidant activities of culturable fungal endophytes associated with the mangrove species Rhizophora stylosa and R. mucronata in the South China Sea

Abstract

Mangrove endophytic fungi can produce impressive quantities of metabolites with promising antioxidant activities that may be useful to humans as novel physiological agents. In this study, we investigated the phylogenetic diversity and antioxidant potential of 46 fungal endophytes derived from the mangrove species Rhizophora stylosa and R. mucronata from the South China Sea. The fungal isolates were identified using a combination of morphological characteristics and phylogenetic analysis of the internal transcribed spacer (ITS) sequences. Seventeen genera belonging to 8 taxonomic orders of Ascomycota were discovered, specifically, Botryosphaeriales, Capnodiales, Diaporthales, Eurotiales, Glomerellales, Hypocreales, Pleosporales, and Xylariales. The most abundant fungal orders included Xylariales (35.49%) and Diaporthales (27.61%), which were predominantly represented by the culturable species Pestalotiopsis sp. (34.54%) and Diaporthe sp. (18.62%). The stems showed more frequent colonization and species diversity than the roots, leaves, hypocotyls, and flower tissues of the host plant. The antioxidant activities of all the isolated fungal extracts on four different culture media were assessed using improved 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) methods. A relatively high proportion (84.8%) of the isolates displayed antioxidant capacity (%RSA > 50%). Further research also provided the first evidence that HQD-6 could produce flufuran as a significant radical scavenger with IC50 values of 34.85±1.56 and 9.75±0.58 μg/mL, respectively. Our findings suggest that the utilization of a biotope such as that of the endophytic fungal community thriving on the mangrove plants R. stylosa and R. mucronata may be suitable for use as a sustainable resource for natural antioxidants.

Diversity and bioactivities of fungal endophytes from Distylium chinense, a rare waterlogging tolerant plant endemic to the Three Gorges Reservoir

“…Some studies have also showed that endophytes can increase the survival rate of host plants during flooding stress by producing antioxidants independently [31,32]. Severe oxidative damage of free radicals has been confirmed to be associated with various diseases, including cancer, inflammation, aging and neurodegenerative diseases [33]. Thus, antioxidants should be warranted in the enhancement of human health [34,35].…”

Cytospyrone and Cytospomarin: Two New Polyketides Isolated from Mangrove Endophytic Fungus, Cytospora sp.

“…Following standard procedures [ 26 ], endophytic fungi were isolated from fresh, healthy hypocotyls of Ceriops tagal (Rhizophoraceae), which were collected in October 2015 in Dong Zhai Gang-Mangrove Garden on Hainan Island, China. The fungus (strain no.…”

Antimicrobial and antioxidant activity of bacterial endophytes isolated from leaves of the mangrove plant <i>Rhizophora stylosa</i>

“…These known compounds from mangrove plant endophytes include terpenes, chromones, coumarins, polyketides, alkaloids, and peptides (Kui-Wu et al, 2014;Xu, 2015;Ancheeva et al, 2018). These compounds exhibit a broad spectrum of biological properties such as antioxidant, cytotoxic, antifungal, antibacterial, α-glucosidase, acetylcholinesterase, antivirus (Kui-Wu et al, 2014;Xu, 2015;Ancheeva et al, 2018;Zhou et al, 2018;Manganyi et al, 2019).…”