Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, Fortaleza, CE, Brazil.
Embrapa Agroindústria Tropical, Fortaleza, CE, Brazil.
Talanta. 2018 Apr 1;180:329-336. doi: 10.1016/j.talanta.2017.12.053. Epub 2017 Dec 21.
The genus Ocimum (Labiatae) comprises 30 species found in tropical and subtropical regions of the planet, of which species O. basilicum L. and O. gratissimum are widely used in food and traditional medicine. Phytochemical studies on Ocimum have revealed a number of essential oil chemotypes, for example, eugenol, methyl chavicol, linalool, and methyl cinnamate. Since essential oils are commercially assessed according to their content, the aim of this study was to develop a simple and precise method for their qualitative and quantitative analysis using NMR spectroscopy combined with chemometrics. Seven essential oils from different species of Ocimum, an unknown sample, and a commercial sample were evaluated and the results compared to those from established and precise GC-MS and GC-FID methods. Chemometric evaluation from both H NMR and GC-MS data revealed three chemotypes: eugenol for O. gratissimum, O. micranthum, and O. tenuiflorum; estragole for O. basilicum, O. basilicum var. purpuracens, and O. selloi; and methyl cinnamate for O. americanum. The unknown and commercial species were classified as cinnamate and eugenol chemotypes, respectively. Despite the corroborating results, the chemometric analysis revealed the higher robustness (better adjustment) of the H NMR model compared to the GC-MS method in terms of certain statistical parameters. The H NMR method allows for the detection and quantification of organic compounds in a complex mixture without the need for certified standard compounds. Although GC-MS and GC-FID were able to detect five compounds not observed by NMR spectroscopy, the four most important metabolites (eugenol, estragole, methyl cinnamate, and eucalyptol) were more readily detected and quantified by H NMR.
罗勒属（唇形科）包含 30 种植物，分布于全球的热带和亚热带地区，其中罗勒（Ocimum basilicum L.）和神圣罗勒（Ocimum gratissimum）被广泛用于食品和传统医学。植物化学研究表明，罗勒属植物包含多种精油化学型，例如丁香酚、甲基丁香酚、芳樟醇和肉桂酸甲酯。由于精油的商业价值取决于其含量，因此本研究旨在开发一种简单而精确的方法，通过 NMR 光谱结合化学计量学对其进行定性和定量分析。我们评估了来自不同罗勒属物种的 7 种精油、一个未知样本和一个商业样本，并将结果与已建立的精确 GC-MS 和 GC-FID 方法进行了比较。来自 H NMR 和 GC-MS 数据的化学计量学评估表明存在三种化学型：丁香酚型，代表植物为神圣罗勒、细籽罗勒和柔弱罗勒；莪术醇型，代表植物为罗勒、紫罗勒和奥罗勒；肉桂酸甲酯型，代表植物为绿罗勒。未知样本和商业样本分别被归类为肉桂酸甲酯和丁香酚化学型。尽管结果一致，但化学计量学分析表明，在某些统计参数方面，H NMR 模型比 GC-MS 方法具有更高的稳健性（更好的调整）。H NMR 方法无需使用认证标准化合物，即可检测和定量复杂混合物中的有机化合物。尽管 GC-MS 和 GC-FID 能够检测到 NMR 光谱未检测到的 5 种化合物，但 H NMR 更易于检测和定量 4 种最重要的代谢物（丁香酚、莪术醇、肉桂酸甲酯和桉油醇）。
