<i>Curcuma longa</i> ethanol extract and Curcumin inhibit the growth of <i>Acanthamoeba triangularis</i> trophozoites and cysts isolated from water reservoirs at Walailak University, Thailand

Abstract

(<i>C. longa</i>) rhizome extract has been traditionally used to treat many infections. Curcumin, a pure compound isolated from the plant, has been documented to possess a wide spectrum of pharmacological effects. The present study aimed to investigate the effects of Thai medicinal plant extracts including <i>C. longa</i> extract and Curcumin on <i>Acanthamoeba triangularis</i>, a causative agent of human <i>Acanthamoeba</i> keratitis. The parasite was isolated from the recreational reservoir at Walailak University, Thailand. The organism was identified as <i>A. triangularis</i> using morphology and 18S rDNA nucleotide sequences. The pathogen was tested for their susceptibility to ethanol extracts of Thai medicinal plants based on eye infection treatment. The ethanol <i>C. longa</i> extract showed the strongest anti-<i>Acanthamoeba</i> activity against both the trophozoites and cysts, followed by <i>Coscinium fenestratum, Coccinia grandis</i>, and <i>Acmella oleracea</i> extracts, respectively. After 24 h, 95% reduction of trophozoite viability was significantly decreased following the treatment with <i>C. longa</i> extract at 125 µg/mL, compared with the control (P < 0.05). The extract at 1,000 µg/mL inhibited 90% viability of <i>Acanthamoeba</i> cyst within 24 h, compared with the control. It was found that the cysts treated with <i>C. longa</i> extract at 500 µg/mL demonstrated abnormal shape after 24 h. The MIC values of <i>C. longa</i> extract and Curcumin against the trophozoites were 125 and 62.5 µg/mL, respectively. While the MICs of the extract and curcumin against the cysts were 500 and 1,000 µg/mL, respectively. The results suggested the potential medicinal benefits of <i>C. longa</i> extract and Curcumin as the alternative treatment of <i>Acanthamoeba</i> infections.