Antioxidant Activity and Phytopathogenic Control of Extracts and Fraction from Struthanthus calophyllus A.C.Sm. (Loranthaceae)

Abstract

AbstractPhytopathogenic microorganisms cause oxidative stress in host plants, thus affecting agricultural crops. Such stress could be controlled by antioxidant compounds from parasitic plants, given their antioxidant power. This article reports an evaluation of Struthanthus calophyllus antimicrobial activity and antioxidant mechanism by testing different polarity extracts. Antimicrobial activity was evaluated against phytopathogens bacteria (e. g., Erwinia, Pectobacterium, Xanthomonas) using the agar diffusion method. Pectobacterium and Xanthomonas presented growth inhibition zones similar to streptomycin control. Antioxidant activity was determined by measuring total phenol content, DPPH⋅, and ABTS⋅+ radicals‐scavenging inhibition percentage (IP). Most polar extracts presented 76,9–95,9 % IP, which correlates with its phenolic content. Besides, Nuclear Magnetic Resonance in a V14‐1 sub‐fraction from stem ethanolic extract, chose one for highest yield percentage, highest metabolites presence, and antimicrobial activity, showed triterpenic compounds mixture (α‐amyrin, β‐amyrin and 24‐methylenecycloartanol). Findings in this study are among the first reports for S. calophyllus, even the chemical characterization, that confirm its strong antioxidant and antibacterial activities. Further molecular composition research about parasitic plants could show how unknown compounds may combat pathogenic microorganisms.