Phytochemical Profiling of Almond Shells: Comparative Analysis of Different Solvent Extracts

Abstract

This study investigates the phytochemical profiles, UV-Vis spectrophotometry, IR spectroscopy, and HPLC analyses of local almond shells extracts using different solvents, including deionized water (DW), ethanol, and a mixture of DW:ethanol (1:1). All extracts contained flavonoids, alkaloids, glycosides, carbohydrates, coumarins, phlobatannins, phytosterols, phenols, quinones, resins, saponins, terpenoids, and triterpenoids, with different concentrations. The DW:ethanol mixture extract also showed the presence of anthraquinones, proteins, and amino acids, which were absent in the other extracts. The DW extract exhibited the highest total flavonoid content (117 mg QE/g), whereas the total polyphenol concentration was greatest in the mixture extract (711 mg TAC/g). The FTIR spectra revealed distinct functional peaks for aromatic rings, unsaturated hydrocarbons, esters, carboxylic acids, ketones, phenols, and alcohols in all extracts. HPLC analysis identified seven prominent phenolic compounds in all extracts, namely benzoic acid, cinnamic acid, gallic acid, ferulic acid, quercetin, kaempferol, and naringenin, with varying concentrations. This study highlights the potential of almond shells as a significant source of bioactive compounds that can function as capping and reducing agents in the environmentally friendly synthesis of nanomaterials. The potential of compounds like flavonoids suggests that almond shell extract is a promising candidate for developing antioxidant drugs.