Antioxidant Activity and UHPLC-MS/MS Characterization of Polyphenol and Nicotine Content in Nicotiana Glauca Leaf Extracts: A Comparative Study of Conventional and Deep Eutectic Solvent Extraction Methods

Abstract

The leaves of Nicotiana glauca (N. glauca; Solanaceae) plant are a known, major human health concern. This study investigated the antioxidant activity and polyphenols composition of aerial parts of N. glauca collected from its wild habitat in Jordan, using Methanol-Conventional (MC) and deep eutectic solvents (DES) extraction methods in addition to nicotine content determination using UHPLC. Our results showed that the MC extract contains fewer total phenols and flavonoid content than the 90% DES extract, (0.1194 ± 0.009 and 0.311 ± 0.020 mg/mL equivalent to gallic acid) and (0.01084 ± 0.005 and 0.928 ± 0.09 mg/mL equivalent to rutin), respectively. Moreover, this study showed that the prepared MC extract contain 635.07 ppm nicotine, while the 90% DES extract contain 1194.91 ppm nicotine. Extracts prepared using the MC and the DES methods exhibited weak antioxidant activities; the highest was a 33% inhibition rate (equivalent to ascorbic acid), obtained by the 90% DES extract,. The performed UHPLC-MS/MS analysis in this study also revealed the presence of variations in the detected compounds between the two extraction methods. Furthermore, this study found that environmentally friendly DES extraction of N. glauca produced higher phenol and flavonoid content than the MC method; this highlights the superior efficiency and environmental benefits of sustainable chemistry methods for extracting valuable phytoconstituents.