Extraction of phenolic compounds from broadleaf plantain (Plantago major L.) leaves using ultrasound

Abstract

Introduction: Broadleaf plantain is a traditional medicinal plant used in folk medicine and phytotherapy in the world. Various pharmacological effects have been demonstrated, such as anti-inflammatory, wound healing, antiviral, anticancer, immunomodulatory [1]. Therapeutic effects are determined by bioactive compounds [2]. Wound healing, anti-inflammatory, antioxidant, anti-carcinogenic, antiviral effects depend on phenolic compounds. The antiviral effect is associated with coffee acid derivatives [3]. The aim of this study is to produce an extract of broadleaf plantain leaves, with highest amount of phenolic compounds and antioxidant activity. Materials and methods: Broadleaf plantain leaves were extracted with 40%, 50%, 60%, 70%, 96% ethanol in a different material and solvent ratio (1:10, 1:20, 1:30). Ultrasound extraction was performed 10 min, 20 min, 30 min, 40 min, 50 min. The total amount of phenolics (TPC) was determined spectrophotometrically by Folin-Ciocalteu reagent, concentration expressed in gallic acid equivalents (GAE mg/mL). The antioxidant activity was evaluated using spectrophotometric DPPH radical scavenging method, results expressed as μg/mL Trolox equivalents (TE). Results: The highest amount was found at the ratio 1:30, after 30 min extraction. When concentration of ethanol was 40% TPC–278.35 GAE mg/mL, 50%–306.5 GAE mg/mL, 60%–399.5 GAE mg/mL, 70%–377.15 GAE mg/mL, 96%–44.64 GAE mg/mL. The highest content of phenolic compounds was when concentration of ethanol was 60%–399.5 GAE mg/mL. The highest antioxidant activity – 211.42 μg/mL TE, after 30 min extraction, at the ratio 1:30. Conclusions: On the basis of the obtained results, the highest antioxidant activity and maximum total amount of phenolic compounds was found in 60% extracts of broadleaf plantain leaves at ratio 1:30 after 30 min ultrasound extraction.