Research progress in biological activity of p-synephrine in cirus fruits

Citrus species contain numerous bioactive compounds including flavonoids, limonoids, vitamins, carotenoids, organic acids and amines. Synephrine, octopomine and tyramine are commonly occurring amines in citrus. It is the most abundant active component of extracts from Citrus aurantium L. unripe fruits. Synephrine is related structurally to endogenous neurotransmitters ( epinephrine and norepinephrine) and has gained significant popularity for the treatment of obesity. Moreover, the ban of ephedrine containing substance by food& drug administration because of an association with serious adverse health effects seems to have resulted in higher consumption of dietary supplements containing synephrine due to their relatively less health risks.Synephrine produces an effect on the human metabolism which could be useful in reducing the fat mass in obese humans, because it stimulates lipolysis and elevates to be metabolic rate and oxidation of fat through increased thermogenesis. However, continuous intravenous infusion of synephrine on healthy volunteers increased the blood pressure, bronchial, cardiovascular and diabetic model mice significantly. It was suggested that the extraction of C. arantium could effectively enhance the liver antioxidant function. The concomitant presence of these substances in dietary supplements containing synephrine likely increase the risk of secondary effects and can constitute a serious concern for health safety. In response to the rapid increase in the use of C.aurantium extracts in weight-loss products and associated concerns from health professionals, the chemical properties and biological activity from citrus species were reviewed.