Chemometric analysis of NMR and GC datasets for chemotype characterization of essential oils from different species of Ocimum.

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 1H 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 1H NMR model compared to the GC-MS method in terms of certain statistical parameters. The 1H 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 1H NMR.

Constituintes químicos voláteis e não-voláteis de Moringa oleifera Lam., Moringaceae / Volatile and non-volatile chemical constituents of Moringa oleifera Lam., Moringaceae

O estudo fitoquímico do extrato etanólico das folhas de Moringa oleifera Lam., Moringaceae, resultou no isolamento dos derivados benzilnitrilas niazirina, niazirinina e 4-hidroxifenil-acetonitrila, enquanto que das cascas dos frutos somente o octacosano foi obtido. Os óleos essenciais das folhas, flores e frutos foram analisados por cromatografia gasosa acoplada a espectrometria de massa. Os constituintes principais identificados foram: fitol (21,6 por cento) e timol (9,6 por cento) nas folhas, octadecano (27,4 por cento) e ácido hexadecanóico (18,4 por cento) nas flores e docosano (32,7 por cento) e tetracosano (24,0 por cento) nos frutos. As estruturas dos compostos isolados foram identificadas a partir de técnicas espectroscópicas (RMN, IV e EM). A 4-hidroxifenil-acetonitrila está sendo citada pela primeira vez para o gênero Moringa e os óleos essenciais das flores e frutos estão sendo citados pela primeira vez para a espécie M. oleifera.

Phytochemical analysis of the ethanol extract from leaves of Moringa oleifera Lam., Moringaceae, yield the benzylnitriles: niazirine, niazirinine and 4-hydroxyphenylacetonitrile, while of fruit shells only octacosane was isolated. The essential oils from leaves, flowers and fruits were examined by gas chromatography-mass spectrometry. The major constituents identified were: phytol (21.6 percent) and thymol (9.6 percent) in the leaves oil, octadecane (27.4 percent) and hexadecanoic acid (18.4 percent) in the flowers oil, docosane (32.7 percent) and tetracosane (24.0 percent) in the fruits oil. The structures of all compounds were identified by spectroscopic analyses (NMR, IR and MS). 4-hydroxyphenylacetonitrile is reported for the first time to the Moringa genus and the essential oils of flowers and fruits are reported for the first time to the species M. oleifera.