Insecticidal and Antifungal Activities of Crude Extracts and Pure Compounds from Rhizomes of Curcuma longa L. (Zingiberaceae)

The insecticidal and antifungal activities of Curcuma longa L. rhizome extracts and two isolated compounds, namely, ar-turmerone and curcumin, were evaluated. Rhizomes of C. longa were extracted with n-hexane, methylene chloride, methanol and water, successively. Hexane, methylene chloride, and methanol extracts exhibited remarkable insecticidal activity against the larvae of Culex pipiens. The LC۵۰ values were ۵.۲۸, ۵.۸۲, and ۶.۴۴ mg L-۱, respectively, after ۴۸ h. In contrary, the extracts exhibited weak toxic effect on the third instar larvae of Spodoptera littoralis. The LC۵۰ values of water, methylene chloride, and hexane extracts were ۴۹۵.۹, ۵۶۵.۷ and ۷۰۹.۷ mg L-۱, respectively after ۴۸ hours. On the other hand, the extracts showed variable antifungal activity against plant pathogenic fungi, Fusarium oxysporum, Pythium debaryanum, Phytophthora infestans, Fusarium solani and Alternaria alternata. Methanol extract had the highest antifungal activity among the tested extracts with EC۵۰ values of ۱۵۹.۸, ۲۴۲.۷, and ۳۲۲.۲ mg L-۱ on P. infestans, F. solani and A. alternata, respectively. Two compounds, namely, ar-turmerone and curcumin were isolated from methylene chloride/methanol (۱:۱) extract of C. longa rhizomes and their chemical structures were identified by using spectroscopic analysis. Ar-Turmerone had moderate toxicity against C. pipiens larvae. The LC۵۰ values were ۱۵۸.۵ and ۱۱۷.۶ mg L-۱ after ۲۴ and ۴۸ hours, respectively. In addition, ar-turmerone showed moderate antifungal activity against P. infestans (EC۵۰= ۵۸۸.۹ mg L-۱) and weak activity against F. solani (EC۵۰= ۸۲۰.۶ mg L-۱). Curcumin caused ۵۱.۱ and ۵۴.۳۲% growth inhibition of F. oxysporum and P. infestans at ۲۵۰ mg L-۱, respectively.

کلیدواژه ها:

Ar-Turmerone ، Curcumin ، Pest control ، Turmeric.