Abstract
Background:
Essential oils have a wide range of pharmacological activities, which determine their widespread use in medicine. Rhizomes with roots Valerian officinalis are used in medicine as sedatives and hypnotics. The pharmacological effect of this type of raw material is due, among other things, to essential oils. The leaves of Valerian officinalis, according to the literature, have a composition similar to that of rhizomes with roots and are promising for study in order to expand the range of raw medicinal plant materials for domestic production.

Aim:
The aim of this study was to quantify the essential oil content in the leaves of V. officinalis and qualitatively analyze it using thin-layer chromatography.

Methods:
Three series of Valerian officinalis leaves were harvested in 2023 from different regions of Belarus. The quantitative determination of essential oil was carried out in accordance with the State Pharmacopoeia of the Republic of Belarus by steam distillation using a Ginsberg apparatus (method B), Clevenger apparatus (method A), and Clevenger apparatus (method C). Qualitative analysis of the essential oil obtained from the leaves of V. officinalis was performed using thin layer chromatography.

Results:
Obtaining essential oil using methods B and C does not allow the extraction of essential oil for further analyses. The essential oil obtained using the Clevenger device (method A) has a light yellow color, does not thicken, does not form an emulsion, and has a peculiar pungent odor characteristic of the producing plant.

Conclusion:
The experimentally selected optimal conditions used to quantitatively determine the essential oil of Valerian officinalis leaves (method A (in accordance with the State Pharmacopoeia of the Republic of Belarus) when distilled for 4 hours, with a raw material-water ratio of 1:10 and using xylene essential oil as a solvent). The quantitative content of essential oil in the leaves of V. officinalis was 9.20±0.67 ml/kg. The essential oil of V. officinalis leaves is composed of sesquiterpene acids, specifically valerenic acid and acetoxyvalerenic acid.

Key words: Essential oil; Valerian officinalis; Ginsberg apparatus; Clevenger apparatus.