Assessment of volatile organic compounds from clove and endophytic fungi for their antifungal and antioxidant properties

Abstract

There are a variety of ecosystems where fungi may be found; they have been evolving for a billion years and are omnipresent. Out of these, several species are pathogenic and can cause significant postharvest loss. Due to frequent use of currently existing chemical interventions for the management of these losses, the phytopathogenic fungi have developed resistance against them. Additionally, these synthetic fungi have negative effect on human health and environment as well. Hence, finding a safer and environment-friendly alternative is crucial for the control of phytopathogenic fungi. Despite the medicinal properties of Syzygium aromaticum, the existence of endophytic fungi within the clove plant that exhibit antifungal and antioxidant properties against phytopathogenic fungi has not been documented. Therefore, the current study examined the antifungal and antioxidant characteristics of volatile organic compounds emitted by clove and endophytic fungi isolated from the medicinal plant S. aromaticum. A total of 23 isolates were isolated from the stem and leaf of the clove plant, and their in-vitro antifungal activity was investigated against major phytopathogens of fruits and vegetables, including Alternaria alternata, Aspergillus niger, Colletotrichum gloeosporioides, Fusarium lateritium, Botrytis cinerea, Fusarium moniliforme, Botryodiplodia theobromae. Two endophytic fungi, #1SALB2, and #8SALB1were identified to fall under Alternaria sp. and Nigrospora sp., respectively, exhibited the highest antifungal activity in dual culture assay. After secondary screening using sandwich plate method, #1SALB2 was found to be the potent most culture; this endophytic fungus can inhibit the growth of selected phytopathogenic fungi by 52.21%- 69.23%.The antioxidant activity of clove extract in 80% acetone and ethyl acetate extract of endophytic fungi was determined using DPPH and FRAP; total phenolic and flavonoid content was also evaluated. The isolate #2SASB8 identified to be a member of Colletotrichum sp. showed the highest antioxidant activity and phenolic content. The potent most endophytic fungi were identified using classical morphotaxonomy. This is the first study to document the antifungal and antioxidant activity of endophytic fungi isolated from S. aromaticum.