Phenolics and antifungal activities analysis in industrial crop Jerusalem artichoke (Helianthus tuberosus L.) leaves

Spoilage of industrial fruits and vegetables in storage and transportation due to fungal infection results in significant losses, and new natural antifungal treatments would have a large economic value. The extracts of antifungal compounds and phenolic acids from Jerusalem artichoke (Helianthus tuberosus L.) leaves were investigated for potential use in enhancing preservation of fruits and vegetables in storage. Either crude leaf extract or n-butanol fraction was active against Botrytis cinerea, Colletotrichum gloeosporioides, Phytophthora capsici Leonian and Rhizoctonia cerealis, with the values of IC50 (half of the maximum inhibitory concentration) ranging from 2466 to 2.534 g L-1 for the crude leaf extract and 0.232-1.911 g L-1 for n-butanol fraction. The severity of grey mould caused by B. cinerea was significantly reduced by n-butanol fraction applied at I and 2 g L-1 (the control efficiency of 71.3% and 77.8%, respectively, compared with commercial preparation Carbendazim. Following in vitro activity-guided fractionation by bioautography, six phenolic acids were separated from n-butanol fraction. Among them, caffeic acid, 3,4-dicaffeoylquinic acid and 1,5-dicaffeoylquinic acid played a dominant role and were active in bioassays against Gibberella zeae, with respective minimum inhibitory concentrations (MIC) being 108, 60 and 4.2 mu g mL(-1). These results imply that Jerusalem artichoke leaves might be a potential source of natural fungicides. (c) 2013 Elsevier B.V. All rights reserved.