Yuan-tong Qi,Yi-Kai Yuan,Jia-Wei Zhang,Yue-Shen Du,Kai-Cong Fu,Ming-Jun Cui,Shu-Shan Du
This paper analyzed the chemical constituents of the essential oil (EO) of Kaempferia rotunda L. and the bioactivities of the predominant compounds. Results obtained from GC/MS analysis indicated 14 compounds, which accounted for 96.66% of the total extract. Among them, the most abundant compound was benzyl benzoate (81.13%), followed by bornyl acetate (4.51%). EO from the medicinal plant K. rotunda inhibited the potent toxicity of Lasioderma serricorne and Liposcelis bostrychophila (LD50=17.1μg/adult and 18.6 μg/adult). K. rotunda oil also exerted strong repellency against three target insects at high concentrations. Based on the theory of the grey correlation analysis, EO from K. rotunda performed better than benzyl benzoate but worse than bornyl acetate on the repellency against Tribolium castaneum. Benzyl benzoate possessed excellent contact toxicity with three target insects. Meanwhile, the binary mixture of two main compounds (benzyl benzoate and bornyl acetate) was evaluated for contact toxicity with T.castaneum for the first time. The synergistic effect in natural ratios has been observed, suggesting that unique mechanisms of action should be responsible for EO toxicity. Plant-derived insecticides appear suitable for developing control means against stored product insects.
Introduction The increasing morbidity of fungal infections and the prevalence of drug resistance highlighted the discovery of novel antifungal agents and investigation of their modes of action. Iron chelators have been used to treat superficial fungal infections or potentiate the efficacy of certain antifungal drugs. Hinokitiol exhibits potent antifungal activity and iron-chelating ability. However, their relationships have not been established. Objectives This study aims to explore the selectivity of hinokitiol against fungal cells and mammalian cells and determine the role of iron-chelating for the antifungal activity of hinokitiol. Methods Iron probe FeRhonox-1 was used to determine intracellular Fe 2+ content. 5-Cyano-2,3-ditolyl tetrazolium chloride probe and Cell Counting Kit-8 were used to detect the mitochondrial respiratory activities. Quantitative real-time PCR and rescue experiments were performed to determine the effect of iron on the antifungal activity of hinokitiol. The effects of hinokitiol on fungal mitochondria were further evaluated using reactive oxygen species probes and several commercial Assay Kits. The ability of hinokitiol to induce resistance in Candida species was carried out using a serial passage method. The in vivo therapeutic effect of hinokitiol was evaluated using Galleria mellonella as an infectious model. Results Hinokitiol was effective against a panel of Candida strains with multiple azole-resistant mechanisms and persistently inhibited Candida albicans growth. Mechanism investigations revealed that hinokitiol chelated fungal intracellular iron and inhibited the respiration of fungal cells but had minor effects on mammalian cells. Hinokitiol further inhibited the activities of mitochondrial respiratory chain complexes I and II and reduced mitochondrial membrane potential, thereby decreasing intracellular ATP synthesis and increasing detrimental intracellular reductive stress. Moreover, hinokitiol exhibited low potential for inducing resistance in several Candida species and greatly improved the survival of Candida -infected Galleria mellonella . Conclusions These findings suggested the potential application of hinokitiol as an iron chelator to treat fungal infections.
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