Antifungal activity of Nepeta elliptica Royle ex Benth. oil and its major constituent (7R)-trans,trans-nepetalactone: A comparative study

Resistance to conventional fungicides has been the major reason of poor control of plant diseases. In recent years, possibility of effective biodegradable natural products from plants as alternative is being worked for controlling pathogenic fungi. The present study was aimed at identification of essential oil constituents of Nepeta elliptica Royle ex Benth., antifungal components and to evaluate mycelium growth and spore germination inhibition potential of the oil and its almost exclusive constituent (7R)trans,trans-nepetalactone (1) (>85% in the oil) against-five plant pathogenic fungi. The data on mycelium growth inhibition of the oil showed high inhibitory activity against Helminthosporium maydis, Fusarium oxysporum and Rhizoctonia solani with IC50 values 115.00, 122.67 and 153.30 mu g/mL, respectively, while 1 displayed antifungal activity against H. maydis and F. oxysporum with IC50 values of 182.74 and 191.68 mu gmL, respectively. It exhibited inhibitory activity against spore germination of five fungi F. oxysporum, H. maydis, Alternaria solani, Curvularia lunata and Albugo candida, with ICso values 571.78, 449.35, 739.67, 471.61 and 822.41 mu g/mL, respectively. The results revealed both the oil and 1 having potential for development of new antifungal agents to suppress common plant diseases. (C) 2014 Elsevier B.V. All rights reserved.