Evaluation of Amomum subulatum Roxb oil as a source of botanical fungitoxicant for the protection of mango fruits from fungal rotting

Abstract

The essential oil extracted from the leaves of Amomum subulatum Roxb. (Zingiberaceae) has been evaluated for efficacy in the control of mango fruit rotting due to fungal infections. The essential oil of A. subulatum exhibited absolute antifungal activity against two mango rotting fungi viz. Botryodiplodia theobromae Pat. and Colletotrichum gloeosporioides Penz, the common storage fungi causing stem end rot and anthracnose disease of mango fruits. The oil showed its absolute fungitoxicity at the minimum inhibitory concentration of 500 μL/L. Its fungitoxic potency did not alter even on a high inoculum density of the test fungi. The Amomum oil significantly enhanced the shelf life of mango fruits by controlling anthracnose disease as well as stem end rot for an additional five and six days, respectively. The oil also inhibited pectinase and cellulase enzymes secreted by the test fungi during pathogenesis and exhibited a wide range of fungitoxicity against 13 fungal isolates. Gas chromatography-mass spectrometry analysis of the oil found 1, 8 cineole to be a major component. The LD50 of Amomum oil was found to be 22,070 mg/kg of body weight in mice (Mus musculus L.) when administered for acute oral toxicity. Keeping in view the side effects of synthetic fungicides, A. subulatum oil may be recommended as a botanical fungitoxicant of plant origin to control the rotting of mango fruits and to enhance their shelf life because of its nonmammalian toxicity and in vivo efficacy. © 2008, The Author(s).