Chemical Composition and Antioxidant Activity of Ethanol Extracts Obtained from Lavender (Lavandula angustifolia Mill.)
Gergana Marovska, Ivanka Hambarliyska, Nadezhda Petkova, Ivan Ivanov, Ivelina Vasileva, Anton Slavov
Abstract
The objectives of the present study were focused on the comparative study of lavender (Lavandula angustifolia Mill.) raw material and its essential oil industry by-products. The potential of the by-products as a natural source of bioactive polar and nonpolar compounds suitable for applications in the food, cosmetic and pharmaceutical industries was investigated. Four lavender samples were studied – three by-products from industrial steam distillation (L-SD20 M, L-SD21 M, and L-SD21 Z) and one raw untreated lavender (L-UNTR21 Z) – and their chemical composition and antioxidant capacity were determined and compared. Nine phenolic acids (gallic, protocatehuic, chlorogenic, caffeic, syringic, p-coumaric, ferulic, salicylic, and rosmarinic acids) and five flavonoids [(+)-catechin, (–)-epicatechin, rutin, hesperidin, and quercetin] were detected in the 70% ethanolic extract of L-SD20 M. The highest amount of phenolic compounds at 16.08 ± 0.38 mg gallic acid equivalents/ g dry weight (dw) were found in the L-SD21 Z 70% ethanolic extract. L-SD21 M 70% ethanolic extract was distinctive with the highest amounts of flavonoids at 3.89 ± 0.44 mg quercetin equivalents/ g dw. The antioxidant capacity of the extracts was evaluated by four methods: radical scavenging activity of 2,2 diphenyl-1-picrylhydrazyl (DPPH assay), ABTS [2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid)], ferric reducing antioxidant power (FRAP), and cupric ion reducing antioxidant capacity (CUPRAC). The highest antioxidant activity by the CUPRAC method was observed in the 70% ethanolic extract of L-SD21 M – 326.49 millimoles Trolox equivalents/g dw. The major aroma constituents found in the 70% ethanolic extracts of L-UNTR21 Z were linalyl acetate and linalool at 38.64 and 7.89%, respectively. τ-muurolol, an oxidated sesquiterpene, was also found in high amounts in the 70% ethanolic extracts from lavender by-products. Therefore, lavender and its industrially generated by-products could represent a promising source of biologically active and aroma compounds with potent high antioxidant activity.