μ-Raman Determination of Essential Oils’ Constituents from Distillates and Leaf Glands of Origanum Plants

Abstract

A novel, inexpensive and simple experimental setup for collecting μ-Raman spectra of volatile liquids in very small quantities was developed. It takes advantage of capillary forces to detain minute volatile liquid volumes. Spectra of volatile and even scattering or absorbing media can be measured more effectively. The method is used to facilitate the collection of intensity-consistent Raman spectra from a series of reference compounds present in Origanum essential oils, in order to quantify their constituents by multiple linear regression. Wild grown Origanum plants, collected from five different regions in Greece and taxonomically identified as O. onites, O. vulgare subsp. hirtum and O. vulgare subsp. vulgare, were appropriately distilled to acquire their essential oils. Comparison of the Raman results with those from headspace gas chromatography–mass spectrometry (HS GC-MS) confirmed the successful relative quantification of the most abundant essential oil constituents, highlighting the similarities and differences of the three Origanum taxa examined. Finally, it is demonstrated that directly measuring the leaf peltate glandular hairs yields exploitable results to identify the main components of the essential oil they contain, underlining the potential of in situ (field or industry) measurements utilizing microscope-equipped portable Raman spectrometers.

Oregano Essential Oil as a Natural Plant Additive Affects Growth Performance and Serum Antibody Levels by Regulating the Rumen Microbiota of Calves

“…Oregano is rich in volatile compounds such as carvacrol, thymol, and monoterpenes, which exhibit different pharmacological properties such as anti-bacterial, anti-fungal, anti-viral, and anti-oxidant; it promotes vasodilatation and is hepatoprotective [ 15 ], so oregano is also used in traditional medicine and Chinese medicine to treat digestive, neurological and respiratory disorders [ 16 ]. Clinical studies have demonstrated the pharmacological potential of oregano in various properties, such as anti-diabetic and hyperlipidemic, cardioprotective and vascular, anti-inflammatory, anti-bacterial, and insecticidal [ 17 ]. Oregano can extract essential oils rich in carvacrol and thymol, a powerful natural antibiotic [ 18 ].…”

Chemical Composition and Pharmacological Activities of Calamintha nepeta Essential Oil

“…Furthermore, EOs exhibit a diverse array of biological actions, including antibacterial, anti-inflammatory, antioxidant, antiproliferative and genoprotective properties. 10,11 Calamintha nepeta (Meuta or Nebta in the Algerian language) is a small aromatic perennial plant with ovals and small leaves, reaching 60 cm in height and classified as members of the Lamiaceae family, which is largely widespread in the Mediterranean region . 12,15 Traditionally, it was employed for both culinary and medicinal purposes as an antiseptic, spasmolytic, diuretic, and cough suppressant.…”