Candida infections are a significant source of patient morbidity and mortality. Candida albicans is the most common pathogen causing Candida infections. Candida auris is a newly described pathogen that is associated with multi-drug-resistant candidiasis and candidaemia in humans. The antifungal effects of various essential oils and plant compounds have been demonstrated against human pathogenic fungi. In this study, the effect of cinnamon leaf and bark essential oils (CEOs) was determined against both C. albicans and C. auris. The disc diffusion (direct and vapour) and broth microdilution method was used to determine antifungal activity of the EOs against selected strains (C. albicans ATCC 10231, C. albicans ATCC 2091 and C. auris NCPF 8971) whilst the mode of action and haemolysin activity of the CEOs were determined using electron microscopy and light microscopy. Direct and vapour diffusion assays showed greater inhibitory activity of bark CEO in comparison with leaf CEO. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of bark CEO for all tested strains was below 0.03% (v/v), which was lower than the MICs of the leaf CEO (0.06–0.13%, v/v) dependent on the strain and the MFCs at 0.25% (v/v). In the morphological interference assays, damage to the cell membrane was observed and both CEOs inhibited hyphae formation. The haemolysin production assay showed that CEOs can reduce the haemolytic activity in the tested C. albicans and C. auris strains. At low concentrations, CEOs have potent antifungal and antihaemolytic activities in vitro against C. albicans and C. auris.

Key points

• Essential oils from Cinnamomum zeylanicum Blume bark and leaf (CBEO and CLEO) demonstrated fungicidal properties at very low concentrations.

• The antifungal activity of CBEO was greater than that of CLEO consistent with other recent published literature.

• The mode of action of CBEO and CLEO was damage to the membrane of C. albicans and C. auris.

• Both CBEO and CLEO inhibited the formation of hyphae and reduced haemolysin production in C. albicans and C. auris.

念珠菌感染是患者发病率和死亡率的重要来源。白色念珠菌是引起念珠菌感染的最常见病原体。黄金假丝酵母是一种新近描述的病原体，与人类的多重耐药性念珠菌病和念珠菌血症有关。各种精油和植物化合物的抗真菌作用已证明对人类病原性真菌具有抑制作用。在这项研究中，确定了肉桂叶和树皮精油（CEO）对白色念珠菌和金黄色念珠菌的作用。圆盘扩散（直接和蒸气）和肉汤微稀释法用于确定EO对选定菌株的抗真菌活性（C. albicans ATCC 10231，C。albicans ATCC 2091和C. auris NCPF 8971），同时使用电子显微镜和光学显微镜确定CEO的作用方式和溶血素活性。与叶CEO相比，直接和蒸气扩散分析显示树皮CEO具有更大的抑制活性。所有测试菌株的树皮CEO的最低抑菌浓度（MIC）和最小杀真菌浓度（MFCs）低于0.03％（v / v），低于叶片CEO的MIC（0.06-0.13％，v / v）取决于应变和MFC的0.25％（v / v）。在形态干扰试验中，观察到细胞膜受损，并且两个CEO均抑制了菌丝的形成。的溶血素生成测定的结果表明的CEO可以降低测试的溶血活性的白色念珠菌和C.耳菌株。在低浓度下，首席执行官具有体外抗抗真菌和antihaemolytic活动白色念珠菌和C.耳。

关键点

•肉桂肉桂皮和叶子的香精油（CBEO和CLEO）在极低的浓度下表现出杀菌作用。

•CBEO的抗真菌活性大于CLEO的抗真菌活性，与其他最近发表的文献一致。

•CBEO和CLEO的作用方式是破坏白色念珠菌和金黄色梭菌的膜。

•CBEO和CLEO均抑制白色念珠菌和金黄色梭菌中的菌丝形成并减少溶血素的产生。