For centuries, plants have been used for a wide variety of purposes, from treating infectious diseases to food preservation and perfume production. Presently, the increasing resistance of microorganisms to currently used antimicrobials in combination with the appearance of emerging diseases requires the urgent development of new, more effective drugs. Plants, due to the large biological and structural diversity of their components, constitute a unique and renewable source for the discovery of new antibacterial, antifungal, and antiparasitic compounds. In the present paper, the history, composition, and antimicrobial activities of the basil, oregano, and thyme essential oils are reviewed.

https://www.koreascience.or.kr:443/article/JAKO201713647762249.pdf

Antimicrobial Activity of Basil, Oregano, and Thyme Essential Oils

High-Performance Thin-Layer Chromatography (HPTLC)

Thin-layer chromatography: challenges and opportunities

Use of essential oils as pesticides or fungicides is safer than chemicals, but it requires plenty of the plant to be effective. Hence, finding the effective compounds of essential oils and their synthesis decreases the problem of preparing the natural compound. The antibacterial effect of Satureja hortensis L., Thymus vulgaris L. essential oils, and their major constituents were determined using the disc diffusion method. These essential oils prevented Erwinia amylovora growth (that causes fire blight disease). The essential oils were fractionated using preparative column chromatography (Silica column) and all fractions were tested for their antibacterial activities on this bacterium. Effective fractions were analyzed by GC-MS. Results showed that carvacrol is the effective compound in Satureja hortensis essential oil and has strong antibacterial effect. The effective compounds in Thymus vulgaris essential oil are thymol and carvacrol. Thymol and carvacrol showed a strong antibacterial effect against E. amylovora in the disc diffusion method. These compounds prevented the growth of E. amylovora in sucrose and nutrient agar media.

Antibacterial Effect of Effective Compounds of Satureja hortensis and Thymus vulgaris Essential Oils against Erwinia amylovora

(HP)TLC is a technique with large applicability in the fields of plant material analysis and stability tests of extracts and finished products. The implementation of a modern standardized methodology led to the increasing of acceptance and recognition of (HP)TLC as competitive analytical method. (HP)TLC has many advantages, such as lower costs, short time analysis, the possibility of multiple detection, and specific derivatization on the same plate, etc. The natural antioxidants (polyphenols) are present in plant extracts; they play a key role in antioxidative defence mechanisms in biological systems and they act as free radicals scavenging agents. The separation of polyphenols from each other and from other components of the plant extracts can be done by a great number of (HP)TLC developed techniques. Mostly, complex crude plant extracts are screened for antioxidant activity or to distinguish the components of plant extracts with antioxidant character or radical‐scavenging properties. (HP)TLC ha...

Analysis of Some Natural Antioxidants by Thin‐Layer Chromatography and High Performance Thin‐Layer Chromatography

Essential oils analysis is more often realized by gas chromatography. However, thin-layer chromatography (TLC) remains the reference for Pharmacopoeia. Nevertheless classical TLC has its own limitations but it is always a good technique because it is simple, rapid and less expensive. Actually the reproducibility, the separation quality and the possibility to obtain good and reproducible quantitative determinations have been improved significantly with automated sample applicator, scanner densitometers and two new chromatographic planar methods: the optimum performance laminar chromatography (OPLC) and automated multiple development (AMD). In this work, we show and compare the performance of these methods and TLC through a study of seven thyme chemotypes and wild thyme essential oil.

Comparison of planar chromatographic methods (TLC, OPLC, AMD) applied to essential oils of wild thyme and seven chemotypes of thyme

Optimal performance laminar chromatography and automated multiple development chromatography are relatively recent techniques of planar chromatography that can be applied with success in plant material analysis. Therefore, these methods are used to study plant extracts and constituents belonging to different chemical classes of secondary metabolism: heterocyclic oxygen compounds (coumarins, flavonoids, and anthocyanins), alkaloids and quaternary ammonium salts, cannabinoids, essential oils, ginsenosides, and cardiac heterosides. Generally, the results obtained with these methods are good, and in most cases they compare with those of thin-layer chromatography.

Claude Viel

Papers

Comparison of planar chromatographic methods (TLC, OPLC, AMD) applied to essential oils of wild thyme and seven chemotypes of thyme

Plant drug analysis by planar chromatography.