Comparative study of phenolic profile and antioxidant activities of different parts of Ziziphus lotus using aqueous, hydroalcoholic and pulsed electric field extractions

Ziziphus lotus (Z. lotus) is a deciduous plant widespread in Tunisia, traditionally used as an infusion or powder for its richness in phenolic compounds, carbohydrates, proteins, and flavonoids. However, the composition varies across different plant parts. In this study, flowers, leaves, stems, roots, and fruits of Z. lotus were analyzed to assess the recovery of antioxidant compounds, with a focus on phenolic profiles, carbohydrates, and proteins, using three extraction methods: pulsed electric field (PEF) extraction, conventional aqueous extraction, and conventional hydroalcoholic extraction (ethanol:water, 80:20 v /v). For the PEF extraction method, 4 g of each plant part were treated at 3 kV/cm and 100 kJ/kg, followed by 1 h stirring. The conventional extractions were performed with water or hydroalcoholic solution under the same stirring conditions. Chemical analyses were conducted by spectrophotometry and Triple TOF-LC-MS/MS for detailed phenolic compound profiling. Statistically significant differences were observed between plant parts and extraction methods. Flowers and leaves showed the highest antioxidant capacity and the richest content in carbohydrates, proteins, and phenolics. Quercetin, a common flavonoid, was highlighted across all parts, while ferulic acid was mainly found in stems and roots. Overall, PEF extraction proved more effective in recovering bioactive compounds compared to conventional methods, highlighting its potential as a green extraction technology aligned with Sustainable Development Goals. • Flavonoids, hydroxycinnamic acids, and lignans were identified in all extracts. • PEF boosts antioxidant activity in flowers; ethanol works best on roots and stems. • PEF enhances catechin and myricetin yield in stems, up to 67.34 %. • Quercetin (50.38 %) and chrysoeriol (3.64 %) are extracted from fruits using Ethanol. • Solvent extraction method alters phytochemical profile compared to PEF extraction.