Extraction of polyphenolic compounds from rose and marigold, UPLC-ESI-QToF-MS/MS, FTIR characterization and assessment of antioxidant activity

Abstract

This study aimed to optimize the process for effective extraction of polyphenolic compounds, flavanoids and antioxidant activity of rose and marigold leaf (RL, ML) and petal (RP, MP) extracts and to analyse their composition. Various drying methods, such as shade, oven (40–70 °C), and microwave (600 W) were utilized for extraction of bioactives with three solvents (water, ethanol, methanol). Microwave dried methanolic extracted samples exhibited high quantities of total phenols, flavanoids, and antioxidants for RL, ML, and MP, while aqueous extracts were found to be the best for extracting bioactives from RP. As the drying temperature increased, the colour values of the extracts decreased. Pigments (chlorophyll, anthocyanin, carotenoids) degraded when the drying temperature increased. The ultra-performance liquid chromatography (UPLC) and fourier transform infrared (FTIR) analysis revealed the primary polyphenol compounds in rose as quercetin, quercetin 3-O-rutinoside, and kaempferol acetyl disaccharide while in marigold they were identified as kaempferol, epicatechin gallate, and feruloyl-caffeoylquinic acid). Also 126 other polyphenolic compounds were identified putatively from rose and marigold through UPLC-ESI-QToF-MS/MS and FTIR. Marigold and rose foliage accounts for 58 % and 82 % of the entire plant's fresh weight, respectively that is usually disposed off as waste. The floral fraction is typically discarded after it has served its primary function. The process of extracting bioactive compounds from these medicinal crops can enhance their value and yield useful products having varying end-use.