Laboratory of Physic and Synthesis Organic Chemistry (LaCOPS), University of Abomey-Calavi, Faculty of Sciences and Technics, BP: 4521 Cotonou, Benin.
Chem Biodivers. 2012 Jan;9(1):139-50. doi: 10.1002/cbdv.201100194.
To determine the period of harvest that optimizes the antimicrobial activities of the essential oil of Ocimum gratissimum L. from Benin, aerial plant parts were collected at two vegetative stages (pre- and full-flowering) and three sampling times (7 am, 1 pm, and 7 pm). Extraction by hydrodistillation yielded between 0.65 and 0.78% of essential oils. Characterization of the oils by GC-FID and GC/MS analysis revealed the presence of monoterpenes (87.26-93.81%), sesquiterpenes (5.57-11.34%), and aliphatic compounds (0.15-0.18%), with p-cymene (1; 28.08-53.82%), thymol (2; 3.32-29.13%), γ-terpinene (3; 1.11-10.91%), α-thujene (4; 3.37-10.77%), and β-myrcene (5; 4.24-8.28%) as major components. Two chemotypes were observed, i.e., a p-cymene/thymol and a p-cymene chemotype, for plants harvested at 7 am for the former and at 1 pm or 7 pm for the latter, respectively. The oils were fungicidal against Candida albicans, with the sample from full-flowering plants collected at 7 am being the most active (MIC = 0.06±0.00 mg/ml). The chemical variation of the oils also influenced the antimicrobial effect against Staphylococcus aureus; the most active oil was obtained from plants at the pre-flowering stage collected at 7 am (MIC=0.24±0.01 mg/ml). Escherichia coli was insensitive to the chemical variation of the oils (MICs of ca. 0.48±0.02 mg/ml for all oils). Moreover, the essential oils showed low toxicity against Artemia salina Leach larvae, with LC(50) values in the range of 43-146 μg/ml. This is the first study of the interaction between the daytime of collection and vegetative stage of the plants and the antimicrobial properties and toxicity of the essential oil of O. gratissimum from Benin.
为了确定优化贝宁罗勒（Ocimum gratissimum L.）精油抗菌活性的收获期，在两个营养生长阶段（初花期和盛花期）和三个采样时间（7:00 am、1:00 pm 和 7:00 pm）采集了空中植物部分。水蒸馏法提取得到的精油含量在 0.65%至 0.78%之间。通过 GC-FID 和 GC/MS 分析对油进行的特征描述表明，存在单萜（87.26-93.81%）、倍半萜（5.57-11.34%）和脂肪族化合物（0.15-0.18%），其中 p- 对伞花烃（1；28.08-53.82%）、百里酚（2；3.32-29.13%）、γ-松油烯（3；1.11-10.91%）、α-蒎烯（4；3.37-10.77%）和β-月桂烯（5；4.24-8.28%）为主要成分。观察到两种化学型，即 p-对伞花烃/百里酚和 p-对伞花烃化学型，分别用于 7:00 am 收获的植物和 1:00 pm 或 7:00 pm 收获的植物。精油对白色念珠菌具有杀菌作用，其中来自盛花期植物的样品在 7:00 am 采集时最活跃（MIC=0.06±0.00 mg/ml）。油的化学变化也影响了对金黄色葡萄球菌的抗菌作用；从初花期植物在 7:00 am 采集的油活性最强（MIC=0.24±0.01 mg/ml）。大肠杆菌对油的化学变化不敏感（所有油的 MIC 约为 0.48±0.02 mg/ml）。此外，精油对卤虫幼虫的毒性较低，LC50 值在 43-146μg/ml 范围内。这是首次研究贝宁罗勒白天采集时间和植物营养生长阶段与精油抗菌性能和毒性之间的相互作用。
