Fabian Dusan, Sabol Marián, Domaracká Katarína, Bujnáková Dobroslava
Institute of Animal Physiology, Slovak Academy of Sciences, Soltésovej 4-6, 04001 Kosice, Slovakia.
Toxicol In Vitro. 2006 Dec;20(8):1435-45. doi: 10.1016/j.tiv.2006.06.012. Epub 2006 Jul 14.
Essential oils are known to possess antimicrobial activity against a wide spectrum of bacteria. The main objective of this study was to evaluate possible harmful effects of four commonly used essential oils and their major components on intestinal cells. Antimicrobial activity of selected plant extracts against enteroinvasive Escherichia coli was dose dependent. However, doses of essential oils with the ability to completely inhibit bacterial growth (0.05%) showed also relatively high cytotoxicity to intestinal-like cells cultured in vitro. Lower doses of essential oils (0.01%) had only partial antimicrobial activity and their damaging effect on Caco-2 cells was only modest. Cell death assessment based on morphological and viability staining followed by fluorescence microscopy showed that essential oils of cinnamon and clove and their major component eugenol had almost no cytotoxic effect at lower doses. Although essential oil of oregano and its component carvacrol slightly increased the incidence of apoptotic cell death, they showed extensive antimicrobial activity even at lower concentrations. Relatively high cytotoxicity was demonstrated by thyme oil, which increased both apoptotic and necrotic cell death incidence. In contrast, its component thymol showed no cytotoxic effect as well as greatly-reduced ability to inhibit visible growth of the chosen pathogen in the doses used. On the other hand, the addition of all essential oils and their components at lower doses, with the exception of thyme oil, to bacterial suspension significantly reduced the cytotoxic effect of E. coli on Caco-2 cells after 1h culture. In conclusion, it is possible to find appropriate doses of essential oils showing both antimicrobial activity and very low detrimental effect on intestinal cells.
众所周知，精油对多种细菌具有抗菌活性。本研究的主要目的是评估四种常用精油及其主要成分对肠道细胞可能产生的有害影响。所选植物提取物对侵袭性大肠杆菌的抗菌活性呈剂量依赖性。然而，能够完全抑制细菌生长的精油剂量（0.05%）对体外培养的肠样细胞也显示出相对较高的细胞毒性。较低剂量的精油（0.01%）仅具有部分抗菌活性，其对Caco-2细胞的损伤作用较小。基于形态学和活力染色并通过荧光显微镜进行的细胞死亡评估表明，肉桂和丁香精油及其主要成分丁香酚在较低剂量下几乎没有细胞毒性作用。尽管牛至精油及其成分香芹酚略微增加了凋亡细胞死亡的发生率，但即使在较低浓度下它们也显示出广泛的抗菌活性。百里香油表现出相对较高的细胞毒性，它增加了凋亡和坏死细胞死亡的发生率。相比之下，其成分百里香酚在所用剂量下既没有细胞毒性作用，抑制所选病原体可见生长的能力也大大降低。另一方面，在培养1小时后，除百里香油外，以较低剂量向细菌悬液中添加所有精油及其成分可显著降低大肠杆菌对Caco-2细胞的细胞毒性作用。总之，有可能找到既具有抗菌活性又对肠道细胞产生极低有害影响的精油合适剂量。
