Antifungal Activity of Various Species and Strains of Turmeric (Curcuma SPP.) Against Fusarium Solani Sensu Lato

Turmeric (Curcuma spp.) are rhizomatous perennial herbs with broad spectrum of pharmacological actions. There are more than 80 species of turmeric and 70 varieties/strains of Curcuma longa, which may have different chemical properties and biological activities. Hence, we compared the major active components (curcuminoides) and antifungal activity of three Curcuma longa strains (Ryudai gold (RD), Okinawa ukon, and BK2), C. xanthorrhiza, C. aromatica, C. amada, and C. zedoaria against Fusarium solani sensu lato (FSSL). The content of curcuminoides was determined by HPLC and the antifungal activity was measured by the diameter of colonies grown on Petri dish, microscopic observation, and CLSI microdilution methods. The BK2 turmeric contained highest concentration of curcumin, demethoxycurcumin, and bisdemethoxycurcumin followed by RD, C. xanthorrhiza, Okinawa ukon, and C. aromatica. These compounds were not detected in C. amada and C. zedoaria. All turmeric species inhibited fungal growth in a concentration-dependent manner. The order of IC₅₀ against FSSL was RD (78 to 92 μg/ml) > BK2 (89 to 101 μg/ml) > C. xanthorrhiza (98 to 114 μg/ml) > C. aromatica (183 to 204 μg/ml) > C. amada (183 to 206 μg/ml) > Okinawa ukon (191 to 216 μg/ml) > C. zedoaria (354 to 385 μg/ml). The results showed a correlation between the antifungal activity and curcuminiods contents of turmeric. Curcumin itself showed marked antifungal activity against FSSL (IC₅₀ = 23 to 25 μg/ml) followed by demethoxycurcumin (IC₅₀ = 25 to 27 μg/ml), while the antifungal activity of bisdemethoxycurcumin was extremely low (IC₅₀ = 216 to 238 μg/ml). However, C. amada and C. zedoaria had no curcuminoids but showed antifungal effects which indicated that other compounds could also inhibit the growth of FSSL. The obtained results demonstrated that turmeric species C. longa (strains Ryudai gold and BK2) and C. xanthorrhiza had higher content of curcuminoids and showed excellent antifungal activity against FSSL.