Eucalyptus brevifolia F. Muell and Eucalyptus stricklandii Maiden leaves extracts: HPLC-DAD, GC-MS analysis and in vitro biological activities, combined with the principal component analysis

Natural products always have been relevant for the advancement of new pharmacological products intended to prevent oxidative stress and many diseases since ancient times. Herein, the chemical composition was investigated via chromatographic analysis of varying polarity solvents (petroleum ether, ethyl acetate, methanol and distilled water) from Tunisian Eucalyptus brevifolia F.M and Eucalyptus stricklandii M. leaves. In vitro provision of biological activities through their antioxidant power (ABTS(.+)), ability to inhibit 15-lipoxygenase (15-LOX), acetylcholinesterase (AChE), xanthine oxidase (XOD), as well as, cytotoxic potency were undertaken. Chemical profiling showed that the methanolic extracts of both species were the richest in total phenolic compounds. GC-MS analysis of the two Eucalyptus species revealed that spathulenol, globulol, epiglobulol, and trans-Z-alpha-bisabolene-epoxide were the main volatile compounds detected in the different extracts. In addition, the derivatization procedure allowed the identification of ethylene glycol, and D-fructofuranose as very abundant molecules. The HPLC-DAD has enabled the identification of eight new molecules among them icariin (1.1 mg/g dr), and 5-hydroxy-3'-methoxyflavone (7.5 mg/g dr) in the E. stricklandii MeOH and EtOAc extracts. Aqueous E. brevifolia extract possessed the highest anti-AChE with an IC50 (10 mu g/mL). Whereas, the MeOH E. stricklandii extract possessed the highest anti 15-LOX with an IC50 (9.7 mu g/mL), as well as, the most important percentage of XOD inhibition 51.1%. All extracts revealed an antiproliferative potency against human cancer cell lines HCT-116, MCF-7 and OVCAR, with an inhibition percentage up to 96%. Taken together, both Eucalyptus species have a broad range of potential applications in several fields, such pharmaceutical, medical and food industries as nutraceutical supplements. (C) 2022 SAAB. Published by Elsevier B.V. All rights reserved.