Antibacterial and cytotoxicity activities and phytochemical analysis of three ornamental plants grown in Mexico

Abstract: This study evaluates the antibacterial, cytotoxic activities, and phytochemical composition, of Callistemon citrinus, Hibiscus rosa-sinensis and Plumbago auriculata leaves and flowers, three ornamental plants in Mexico. However, in other countries offers a range of other uses. Ethanol extracts of C. citrinus leaf and flower presented stronger antibacterial activity than the extracts obtained from the other two plants. C. citrinus leaf showed low cytotoxicity (LC50 <600 µg/mL) on the brine shrimp test, whereas the ethanol extracts of H. rosa-sinensis and P. auriculata leaves showed no cytotoxic activity. Flower extracts obtained from the three plants did no exhibit cytotoxicity. GC-MS analysis revealed that the ethanol extract of P. auriculata leaf contained lupeol triterpene and lupeol acetate, neither of them have been previously reported in this genus. Gamma sitosterol was present in the leaf and flower extracts of P. auriculata. Higher contents of linoleic and linolenic acids were found in extracts of H. rosa-sinensis leaves and flowers. The ability of the ethanol extracts of C. citrinus leaves and flowers to inhibit the growth of Gram-positive and Gram-negative bacteria indicates a potentially broad antimicrobial spectrum. Moreover, the absence of cytotoxicity suggests the potential use of this plant to treat microbial infections.

摘要：本研究针对墨西哥本土的三种观赏植物——红千层（Callistemon citrinus）、朱槿（Hibiscus rosa-sinensis）以及蓝花丹（Plumbago auriculata）的叶片与花材，系统评估其抗菌活性、细胞毒性及植物化学成分组成。尽管这三种植物在墨西哥仅作为观赏植物栽培，但在其他国家却拥有多种不同的应用途径。红千层的叶片与花材乙醇提取物的抗菌活性显著优于另外两种植物的提取物。红千层叶片提取物在卤虫急性毒性试验（brine shrimp test）中表现出较低的细胞毒性（半数致死浓度LC₅₀ < 600 μg/mL），而朱槿与蓝花丹的叶片乙醇提取物则未检测到细胞毒性。三种植物的花材提取物均未表现出细胞毒性。气相色谱-质谱联用（GC-MS）分析结果显示，蓝花丹叶片的乙醇提取物含有羽扇豆醇三萜（lupeol triterpene）与羽扇豆醇乙酸酯（lupeol acetate），这两种成分此前均未在该属植物中被报道过。γ-谷甾醇（gamma sitosterol）存在于蓝花丹的叶片与花材提取物中。朱槿的叶片与花材提取物中亚油酸与亚麻酸的含量更高。红千层叶片与花材的乙醇提取物可抑制革兰氏阳性菌与革兰氏阴性菌的生长，这表明其具备潜在的广谱抗菌活性。此外，该植物提取物未表现出细胞毒性，提示其具备开发用于治疗微生物感染的相关制剂的潜力。