In vitro antifungal activity and phytochemical characterization of Eugenia uniflora, Libidibia ferrea and Psidium guajava

The aim of this study was evaluate the in vitro antifungal activity of crude extracts from Eugenia uniflora, Libidibia ferrea and Psidium guajava. The extracts were obtained by turbo-extraction using water (AQ) or acetone-water (AC-W) (7:3, v/v) as solvents and lyophilized to obtain the crude extracts (CE). The CE were characterized by UV-Vis, TLC and HPLC. The activity of CEs was investigated against clinical isolates of Candida spp. and the Minimum Inhibitory Concentration (MIC), MIC50 and MIC90 were determinated. The analysis by TLC showed that all CEs presented polyphenols (flavonoids and tannins). The CEs from E. uniflora showed higher amount of polyphenols (30.35 ± 2.15%, AC-W) and the HPLC analysis revealed the tannins in all extracts. The CEs of E. uniflora showed MIC range from 1.9 to 500.0 µg/mL, and lower values of MIC50 and MIC90 against non-albicans Candida isolates. Regarding L. ferrea and P. guajava, the results showing MIC from 3.9 to 1000.0 µg/mL (CE-AQ) against C. albicans. The results demonstrate antifungal performance from CE against various species of Candida spp., suggesting that the herbal species may be use as new potential antifungal agents. Additionally, the polyphenol content can play a pivotal role in the antifungal properties of CE.本研究旨在评估红果仔（Eugenia uniflora）、巴西苏木（Libidibia ferrea）与番石榴（Psidium guajava）粗提物（crude extract, CE）的体外抗真菌活性。实验以水（AQ）或丙酮-水（AC-W，体积比7:3，v/v）为溶剂，通过涡轮萃取法制备提取物，经冷冻干燥得到粗提物（CE）。采用紫外-可见光谱法（UV-Vis）、薄层色谱法（TLC）与高效液相色谱法（HPLC）对粗提物进行表征。针对念珠菌（Candida spp.）临床分离株，考察了粗提物的抗真菌活性，并测定了最低抑菌浓度（Minimum Inhibitory Concentration, MIC）、MIC50与MIC90。薄层色谱分析结果显示，所有粗提物均含有多酚类成分（黄酮类与鞣质类）。红果仔粗提物的多酚含量最高（丙酮-水提取物组为30.35 ± 2.15%），高效液相色谱分析证实所有提取物中均含有鞣质。红果仔粗提物对念珠菌的最低抑菌浓度范围为1.9~500.0 µg/mL，针对非白念珠菌分离株的MIC50与MIC90值更低。针对巴西苏木与番石榴粗提物，其水提粗提物（CE-AQ）对白念珠菌（C. albicans）的最低抑菌浓度范围为3.9~1000.0 µg/mL。研究结果表明，粗提物对多种念珠菌均具有抗真菌活性，提示上述草本植物可作为新型潜在抗真菌剂加以开发。此外，多酚类成分可能在粗提物的抗真菌特性中发挥关键作用。