لیموترش تونس: خواص فیتوشیمیایی و فیزیکوشیمیایی بیولوژیکی Citrus limon from Tunisia: Phytochemical and Physicochemical Properties and Biological Activities

1. Introduction In recent years, many diseases have appeared and are mainly due to “oxidative stress” which is the result of an imbalance between the formations or not of prooxidants [1]. Indeed, reactive oxygen species (ROS) are reactive molecules due to the presence of unpaired electrons such as superoxide anion radicals (O2 ∙−), hydroxyl radicals (OH∙ ), hydroperoxyl radicals (HOO∙ ), peroxyl (ROO∙ ), and also nonradical species such as hydrogen peroxide (H2O2), ozone (O3), and singlet oxygen (1 O∙ 2) [2]. Oxidative stress is caused by the presence of free radicals that upset stability by electronic pairing with several biological macromolecules such as proteins, lipids, and DNA and cause significant damage to the basic structures of the body (proteins, lipid, and DNA) [1, 3]. Evidences that ROS accumulation in biological systems causes oxidative tissue damage and affects cellular integrity and function are tangible. Oxidative damage caused by ROS has often been the origin of the pathogenesis of several diseases such as aging, arthritis, cancer, inflammation, and heart disease [4]. Lemon is among the most important crops in the world, with an annual production of about 123 million tons in 2010. Lemon (Citrus limon L.) occupies the third most important Citrus species after orange and mandarin world production by 4.200.000 metric tons [5]. Lemon (Citrus limon L.) is a main element of the Tunisian economy. In fact, lemon and lime production reached nearly 27.000 tons in 2005 [6]. The genus Citrus includes several important species worldwide, oranges by 56%; tangerines and clementines: 17%; lemons and limes: 11%; and finally grapefruit: 6% of the total [7]. Lemon is very rich in important natural compounds, including citric acid, ascorbic acid, minerals, flavonoids, and essential oils. Therefore, although the new Citrus cultivars have been mainly developed for fresh consumption, the particular characteristics such as their phenolic compound and in particular the flavonoids contents have led to their use in new fields such as pharmacology and food technology [8]. Citrus fruits are mainly used in food industries for the production of fresh juices. Thanks to their important composition in bioactive molecules (natural antioxidants, phenolic acids, and flavonoids), peels, the main fraction of Citruswaste which represent approximately half of the mass of the fruit, have been widely studied [2].