Chemical Composition, Antioxidant Activity, and Control Potential of Botanical Fermented Products on Phytopathogenic Fungi of Agricultural Interest

Abstract

Purpose: This work aimed to evaluate the chemical composition and bioactivity of fermented extracts of the botanical species Platycladus orientalis, Cupressus sempervirens, Ricinus communis, Artemisia absinthium, and Picrasma crenata, assessed at 10 %, 20 %, and 40 % v/v on the mycelial development of phytopathogenic fungi Colletotrichum fructicola, Sclerotium rolfsii, and Fusarium oxysporum.   Theoretical framework: The search for sustainable alternatives that are less harmful to the environment regarding synthetic agrochemicals has intensified in recent years. Among the different approaches to mitigate this problem, the use of molecules of biological origin and biotransformed botanical extracts is an important research topic in the area. However, the potential for using fermented botanical extracts is still little explored, and it is necessary to study these materials to evaluate their actual biological activity systematically and, consequently, the potential for practical use, especially in areas such as agriculture.   Methods: The antioxidant activity before and after the fermentation process, as well as the levels of phenolic compounds, flavonoids, and individual phenolics, were determined by spectrophotometry and high-performance liquid chromatography. The mycelial growth of Colletotrichum fructicola was evaluated in vitro in a PDA medium containing the fermented ones at zero, 10 %, 20 %, and 40 % v/v.   Results and conclusion: The main phenolic compound identified was gallic acid in fermented A. absinthium, followed by P. crenata and R. communis. These same species showed inhibitory activity between 44.0 % and 34.6 %, at a concentration of 40 % v/v, on the mycelial development of C. fructicola. As for the antioxidant activity of the analyzed fermented products and the evaluation of phenolic compounds before and after the fermentation of plant extracts, the results before varied between 58 – 79 %, and in the post-fermentation, the activity was maintained only for the fermented products of C. sempervirens and P. orientalis, a fact also verified in the same species relative to the levels of phenolic compounds. No inhibitory effect was observed on the fungi, showing that these fermentates are ineffective as antifungal agents.   Research implications: This work showed that these botanical fermented products do not have any antifungal effect on these phytopathogens. So, further research is necessary to improve their antifungal effect.   Originality/value: Few studies address the biological activity of fermented extracts and their potential for agricultural application. In this sense, the present study aims to verify the antifungal activity of different botanical fermentates to evaluate their potential use as an alternative to synthetic products.