Role of Solvent Polarity in the Extraction and Electrochemical Behavior of Antioxidants From Ziziphus jujuba Leaves.
Kalsoom Umme U, Hussain Zahid Z, Khan Salman S, Ahmad Naveed N et al.
Ziziphus jujuba is a medicinal plant known for its rich content of antioxidants including flavonoids, saponins, phenolics, and triterpenoids. This study determines the effect of solvent polarity on the extraction yield and investigates phytochemical distribution of the extracts and its electrochemical behavior. Reflux extraction was used for the preparation of crude extracts, using methanol, ethanol, and water. The ethanolic extract was selected for solvent fractionation, using n-hexane, dichloromethane, chloroform, and ethyl acetate. Among the extraction solvents, ethanol produced the highest crude yield (6.0% w/w). Following solvent-solvent fractionation, the ethyl acetate fraction showed the highest recovery among all fractions (0.30% w/w). The presence of flavonoid and saponin fractions was confirmed by phytochemical screening. The highest absorbance was observed in ethyl acetate fraction through UV visible spectrophotometric analysis, A = 0.711 for flavonoids at 415 nm and 0.330 for saponin at 406 nm. Cyclic voltammetry (CV) for ethyl acetate and chloroform fractions showed oxidation peaks at 0.50 V (vs. Ag/AgCl). Fourier transformed infrared spectroscopy (FT-IR) analyzed functional groups of flavonoids and saponins. Liquid chromatography mass spectrometry (LC-MS) identified major flavonoids, that is, vicenin II, spinosin, kaemferol (glycoside), and saponins (jujubosides). The result stated that the polarity of solvents plays a vital role in extracting redox-active antioxidants from the leaves of Z. jujuba. Furthermore, it stated that ethyl acetate is the most effective fractionation solvent. This study gives analytical framework for extraction and characterization of antioxidant-rich fraction of Z. jujuba leaves along with emphasis on the role of solvent polarity in phytochemical recovery.