Ital. J. Food Sci., vol. 31, 2019 - 556 PAPER CHEMICAL COMPOSITION, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF ALOYSIA TRIPHYLLA L. ESSENTIAL OILS AND METHANOLIC EXTRACT L. REZIG 1 , M. SAADA 2 , N. TRABELSI 3 , S. TAMMAR 2 , H. LIMAM 2 , I. BETTAIEB REBEY 2 , A. SMAOUI 3 , G. SGHAIER 2 , G. DEL RE 4 , R. KSOURI 2 and K. MSAADA* 2 1 High Institute of Food Industries, 58 Alain Savary Street, El Khadra City, Tunis, 1003, Tunisia 2 Laboratory of Aromatic and Medicinal Plants, Biotechnology Center in Borj Cedria Technopole, BP. 901 Hammam-Lif 2050, Tunisia 3 Laboratory of Olive Biotechnology, Biotechnology Center of Borj-Cedria, P.O. Box 901, 2050 Hammam-Lif, Tunisia 4 Università dell'Aquila, Dipartimento di Ingegneria Industriale e dell'Informazione e di Economia, Piazzale Ernesto Pontieri, Monteluco di Roio, 67100 L'Aquila, Italy *Corresponding author: Tel.: +21622205878; Fax: +21679412638 E-mail address: msaada.kamel@gmail.com ABSTRACT The essential oil variability in aerial parts of Aloysia triphylla, collected from four different Tunisian regions was assessed. In addition, total polyphenols, flavonoids, and condensed tannins as well as antioxidant, antibacterial, and antifungal activities of methanolic extract and essential oils were determined. Chromatographic analysis of Aloysia triphylla essential oils showed the predominance of monoterpene aldehydes represented mainly by neral and geranial. RP-HPLC analysis of Aloysia triphylla methanolic extract revealed the predominance of p-coumaric acid among the 15 phenolic acids identified. Antiradical activity was region-dependent and the methanolic extract of Kairouan sample had the strongest activity. Concerning the reducing power, the methanolic extract of Kairouan, Siliana, Kairouan, and Gabes samples were less active than the positive control. Siliana sample showed the least ability to prevent the bleaching of β-carotene, whereas Kairouan sample exhibited the strongest activity. Obtained results of antimicrobial and antifungal activities showed that Aloysia triphylla essential oil was endowed with important antibacterial and antifungal properties. Overall, based on its methanolic extract and essential oil features, Aloysia triphylla may be considered as a valuable source of new multipurpose products for industrial, cosmetic, and pharmaceutical utilization. Keywords: Aloysia triphylla L., regions, phenolic, essential oils, antioxidant activity, antimicrobial activity