Vinh University, College of Education, Faculty of Biology, Nghe An, Vietnam.
Cracow University of Technology, Cracow, Poland.
Braz J Biol. 2023 Apr 3;84:e270967. doi: 10.1590/1519-6984.270967. eCollection 2023.
The present study is the first to investigate the chemical composition, antimicrobial and larvicidal activities of the essential oils from the leaves of Syzygium attopeuense (Gagnep.) Merr. & L.M.Perry and Syzygium tonkinense (Gagnep.) Merr. & L.M.Perry collected in Vietnam. The essential oils were extracted by hydrodistillation and analyzed by GC and GC-MS. The study indicated the presence of a high percentage of sesquiterpenes in both investigated essential oils. The major components of S. attopeuense essential oil were bicyclogermacrene (24.26%), (E)-caryophyllene (11.72%), and (E)-β-ocimene (6.75%), whereas S. tonkinense essential oil was dominated by (E)-caryophyllene (80.80%). The antimicrobial activity of essential oils was evaluated by broth microdilution assay to determine the minimum inhibitory concentration (MIC) and median inhibitory concentration (IC50). Both essential oils exhibited remarkable inhibitory activity against all tested Gram-positive bacteria and yeast than Gram-negative bacteria. Among them, essential oils of S. attopeuense and S. tonkinense possessed the strongest activity against Enterococcus faecalis (MIC = 4.00 μg/mL; IC50 = 1.69 μg/mL) and Candida albicans (MIC = 16.00 μg/mL; IC50 = 8.67 μg/mL), respectively. Furthermore, the larvicidal activity of essential oils was tested using fourth-instar larvae of Aedes aegypti. Results from the larvicidal test revealed that both essential oils had an excellent inhibitory effect against A. aegypti larvae with LC50 values from 25.55 to 30.18 μg/mL and LC90 values from 33.00 to 39.01 μg/mL. Our findings demonstrate that the essential oil extracted from S. attopeuense and S. tonkinense are potential sources of natural antimicrobials and can act as inexpensive mosquito larvicidal agents.
本研究首次调查了采自越南的 Syzygium attopeuense（Gagnep.）Merr. & L.M.Perry 和 Syzygium tonkinense（Gagnep.）Merr. & L.M.Perry 叶片的精油的化学成分、抗菌和杀幼虫活性。精油通过水蒸馏提取，并通过 GC 和 GC-MS 进行分析。研究表明，两种所研究的精油中都含有高比例的倍半萜烯。S. attopeuense 精油的主要成分是双环倍半萜（24.26%）、（E）-丁香烯（11.72%）和（E）-β-罗勒烯（6.75%），而 S. tonkinense 精油则以（E）-丁香烯（80.80%）为主。通过肉汤微量稀释法评估精油的抗菌活性，以确定最小抑菌浓度（MIC）和半数抑制浓度（IC50）。两种精油对所有测试的革兰氏阳性菌和酵母都表现出显著的抑制活性，而对革兰氏阴性菌的抑制活性较弱。其中，S. attopeuense 和 S. tonkinense 的精油对粪肠球菌（MIC = 4.00 μg/mL；IC50 = 1.69 μg/mL）和白色念珠菌（MIC = 16.00 μg/mL；IC50 = 8.67 μg/mL）的活性最强。此外，还使用埃及伊蚊的第四龄幼虫测试了精油的杀幼虫活性。杀幼虫试验的结果表明，两种精油对埃及伊蚊幼虫均有极好的抑制作用，LC50 值为 25.55-30.18μg/mL，LC90 值为 33.00-39.01μg/mL。我们的研究结果表明，从 S. attopeuense 和 S. tonkinense 中提取的精油是天然抗菌剂的潜在来源，可作为廉价的蚊虫幼虫杀剂。
