Polyphenols in northern Hungarian Mentha longifolia (L.) L. treated with ultrasonic extraction for potential oenological uses

Abstract

The main objective of this study is to investigate three equalized batches of a wild Mentha longifolia (ML) population fromnorthern Hungary for extractability by gentle ultrasonic extraction, antioxidant activity, and phenolic constituents. This is the firstanalytical investigation in a Hungarian population of this species. Antioxidant properties of ML extracts were evaluated with DPPH,photochemiluminescence-O2-• scavenging assay, FRAP, and total polyphenol measurements. HPLC-DAD determination was performedfor the main phenolic constituents. The extracts are medium or strong antioxidants in DPPH and FRAP assays and show strong O2-•scavenging capacity. Rutin, quercetin, kaempferol, apigenin, naringenin, rosmarinic, vanillic, gallic, syringic, caffeic, and ferulic acidswere identified. All batches were unexpectedly rutin-rich (1700–7500 mg/kg dry herb) and also were rich in rosmarinic acid. Furthercharacteristic traits in the polyphenol profile were a lack of naringenin and (previously not reported) the presence of free kaempferol(up to 30 mg/kg dry herb).