Inhibition of Rhizoctonia solani Growth and Its Extracellular Hydrolytic Enzymes by Different Extracts of Cinnamon (Cinnamomum cassia) and Black Cumin Seeds (Nigella sativa)

Abstract

The present study evaluated the ability of different extracts of cinnamon and black cumin seeds to inhibit the growth of the phytopathogen-ic fungus Rhizoctonia solani and its extracellular cell wall degrading en-zymes. Concentrations of 300 and 450 ppm of methylene chloride and hex-ane extracts of cinnamon completely inhibited the growth of R. solani after 72 hours of incubation at 25±1°C in vitro. Methylene chloride or hexane ex-tracts of black cumin seeds at 4000 ppm after 72 hours inhibited the growth of R. solani by 37 and 39% respectively. Moreover, black cumin seed hexane extract at 2000 ppm inhibited 55% and 38% of the activity of pectin lyase (PL) and polygalacturonase (PG) respectively. In addition, the methanolic extract of black cumin seeds at 2000 ppm exhibited a significant reduction of exo-protease activity (74.8%). GC-MS analysis results showed that linoleic acid is the main component of the fixed oil fraction of black cumin seed hex-ane extract while (E)-cinnamaldehyde is the main component in both hexane and methylene chloride extracts of cinnamon. HPLC-MS analysis of black cumin seeds methanolic extract showed that amentoflavone, was the main component. Docking was used to identify the major component interaction with pectin lyase A and exo-protease.