**1. Introduction**

Hesperidin (HSD) is a secondary plant metabolite and one of the principal bioflavonoids of citrus fruits. This flavanone and its aglycone form, hesperetin (HST), are present in relatively high quantities (1–2%), especially in sweet immature oranges (*Citrus sinensis*) [1,2]. HSD is known for valuable bioactivity and can act as an antioxidant [3–10], anti-inflammatory [3,9,10], hypolipidemic [8], vasoprotective [3,4,8,11], and anticancerogenic [3,9] agent. The grea<sup>t</sup> majority of flavanones are glycosylated mainly with rutinose and neohesperidose [1,12]. HSD (Figure 1) is proposed, after di fferent in vitro studies, as a plant defense molecule and a potent antioxidant [7,13]. It is water soluble just at high pH, dimethyl sulfoxide, and pyridine, giving yellow and clear solutions. HSD is partially soluble in methanol and glacial acetic acid, and almost insoluble in acetone, chloroform, and benzene [12,14].

**Figure 1.** Chemical structure of hesperidin (2*S*)-5-hydroxy-2-(3-hydroxy-4-methoxyphenyl)-7-[(2*S*,3*R*, <sup>4</sup>*S*,5*S*,6*<sup>R</sup>*)-3,4,5-trihydroxy-6-[[(2*<sup>R</sup>*,3*R*,4*R*,5*R*,6*S*)-3,4,5-trihydroxy-6-methyloxan-2-yl]oxymethyl]oxan-2- yl]oxy-2,3-dihydrochromen-4-one). HSD carbon atoms are numbered, and A–C rings are shown.
