Chemical composition and in vitro antifungal activity of turmeric oil from Curcuma longa L. rhizome against Colletotrichum spp.

Abstract

The production of curcumin produces large quantities of the spent turmeric oleoresin as a by-product, which often pollutes the environment. This study was conducted to obtain turmeric oil from this by-product and evaluate its antifungal activity. Turmeric oil afforded by partitioning the turmeric oleoresin from the production of curcumin (Curcuma longa L.) with n-hexane showed a strong inhibition for Colletotrichum species. The volatile components of turmeric oil were determined by GC-MS. Then, 23 volatile compounds were identified from this oil, of which four main compounds were α-zingiberene, α-turmerone, ar-turmerone, and β-sesquiphellandrene. Besides, the authors also isolated Colletotrichum gloeosporioides from lychee fruits, which were harvested in Luc Ngan district, Bac Giang province. By poisoned food technique, the antifungal activity of turmeric oil against C. gloeosporioides, C. orbiculare, C. acutatum, Phytophthora infestans, and Fusarium oxysporum was demonstrated. The results showed that at a concentration of 1 mg/ml, turmeric oil showed the highest inhibitory effect on C. gloeosporioides (67.9%). As for other fungi, in vitro growth inhibition varied in the range of 41-62%.