Phytochemical screening and antimicrobial activities of Guizotia abyssinica L. leaf and flower extracts

Abstract

Sustainable agricultural systems demand less or no use of synthetic chemicals, which have various adverse effects on the environment and human health. In this context, studies on phytochemicals with antimicrobial and antioxidant properties hold great promise to suppress plant diseases and, thereby, reducing the application of synthetic chemical pesticides. Such an alternative approach requires screening and identification of bioactive compounds from various plant species. In the present study, Guizotia abyssinica L., an oilseed crop plant that usually requires less water with no pesticide inputs to grow, was screened for its potential antioxidant and antimicrobial phytochemicals. The methanolic and aqueous extracts of leaves and flowers of G. abyssinica were tested for their polyphenol content (total phenols and flavonoids) and antioxidant potential. The antioxidant and free radical scavenging activities of both methanolic and aqueous extracts were higher in comparison to many previously reported plant extracts. Furthermore, leaf extracts of G. abyssinica have shown slightly higher antioxidant activity than flower extracts. In vitro antimicrobial studies confirmed the inhibitory effect of methanolic extracts of leaves and flowers against phytopathogens like Xanthomonas oryzae RR24, Fusarium sp. and Alternaria sp. The chemical nature and composition of these crude extracts were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography Mass Spectrometry (GC-MS). Approximately, 28 bioactive compounds detected in GC-MS were predicted to have antimicrobial activity. Based on our results, we conclude that the extracts derived from G. abyssinica have demonstrated remarkable efficacy in inhibiting the proliferation of phytopathogens, thus exhibiting immense potential in promoting sustainable agricultural practices.