Impact of extraction techniques on antioxidant properties and phenolic composition of extracts from different Satureja montana chemotypes cultivated in Serbia

Abstract

Satureja montana (SM), an aromatic species of the Lamiaceae family, exhibits notable chemical polymorphism in its essential oil (EO) composition, primarily characterized by two dominant chemotypes: the carvacrol chemotype (carvacrol 50–70 %), predominant in Mediterranean regions, and the thymol chemotype (thymol 30–60 %), common in the Balkan Peninsula. A mixed carvacrol–thymol chemotype (both compounds 20–40 %) is frequently found in transitional zones between these areas. The chemotype-specific composition influences biological activity and sensory properties, guiding the selection of plant material for pharmaceutical, cosmetic, and food applications. However, it remains unclear whether such chemotypic variation extends to plant extracts, particularly those obtained using different extraction techniques. This study investigated how three extraction methods—maceration (M), ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE)—affected the chemical composition, antioxidant activity, and yield of bioactive compounds in SM extracts derived from these chemotypes cultivated in South Banat, Serbia. High-Performance Liquid Chromatography (HPLC) analysis identified key phenolic compounds, including thymol, carvacrol, rosmarinic acid, rutin, and caffeic acid. MAE extracts exhibited the highest total polyphenol content (TPC) and total flavonoid content (TFC), with SM (T) extracted by MAE consistently showing the greatest concentrations of rosmarinic acid and rutin, along with superior antioxidant activity measured by ion exchange-based antioxidant assays (FRAP and CUPRAC). UAE was particularly efficient in extracting thymol and carvacrol, especially in the SM (T) chemotype, leading to higher activity in radical scavenging antioxidant assays (ABTS and DPPH). These results underscore the significant impact of both chemotype and extraction technique on the bioactive profile of SM extracts. Optimizing extraction based on chemotype is thus crucial for enhancing the therapeutic efficacy and industrial value of S. montana.