Selection of the optimal extractant for the extraction of phenolic compounds from Laurus nobilis L. leaves

Abstract

Aim. To select the optimal extractant for the extraction of a number of groups of phenolic compounds from Lаurus nоbilis L. leaves based on the determination of the quantitative content of these groups in the extracts obtained. Materials and methods. Lаurus nоbilis L. leaves were harvested in November 2020 from artificially cultivated specimens aged 5 – 7 years. The quantitative determination of polyphenols was performed using the spectrophotometric method at a wavelength of 760 nm in accordance with the requirements of the Supplement of the State Pharmacopoeia of Ukraine (SPhU) 1.2 (2.8.14). The quantitative content of this group of compounds was calculated with reference to pyrogalol and dried substance. The quantitative determination of the amount of hydroxycinnamic acids was performed according to the SPhU 2.2 monograph “Orthosyphon stamen (kidney tea) leavesN” by the spectrophotometric method at a wavelength of 505 nm and calculated with reference to rosmarinic acid. The quantitative determination of the amount of flavonoids was performed according to the SPhU 2.0 monograph “Hawthorn leaves and flowers” by the spectrophotometric method at a wavelength of 410 nm and calculated with reference to hyperoside.Results and discussion. The analysis of the results for the quantitative determination of polyphenols, the amount of hydroxycinnamic acids and the amount of flavonoids in extracts from Lаurus nоbilis L. leaves obtained using water, water-ethanol mixtures and 96 % ethanol showed that 70 % ethanol was optimal for extracting compounds of these groups. The quantitative content of polyphenols (calculated with reference to pyrogalol) was not less than 21 %, the amount of hydroxycinnamic acids (calculated with reference to rosmarinic acid) – not less than 3 %, the amount of flavonoids (calculated with reference to hyperoside) – not less than 5 %. Conclusions. For the first time, the quantitative content of a number of groups of phenolic compounds (polyphenols, the total amount of hydroxycinnamic acids, and the total amount of flavonoids) in Lаurus nоbilis L. leaves extracts obtained using various extractants has been determined. On this basis, the optimal extractant – 70 % ethanol for the extraction of phenolic compounds has been selected. The results obtained will be used when developing the technology for obtaining substances from Lаurus nоbilis L. leaves.