Nutritional Value, Bioactive Components and Antioxidant Activity of Schisandra chinensis (Turcz.) Baill. Leaves

Abstract

As a part of the ongoing interest in the nutritional and antioxidative properties of a little-known East Asian plant species, the aim of the study was to determine the contents of macronutrients and selected elements, profiles of fatty and amino acids, the content of phenolic compounds, β-carotene, vitamin A and E, and antioxidant activity of Schisandra chinensis (Turcz.) Baill. edible leaves. Schisandra chinensis leaves contained a small amount of lipids – 4.36 % and 12.38 % of proteins. Sugars (fructose, maltose, sucrose, and lactose) were detected only in trace amounts (<0.5 g/kg). The β-carotene content was 17.70 mg/kg. The fatty acid profile of leaves was represented by palmitic C16:0 (44.6 g/100 g of oil), linoleic C18:2 9c12c (17.9 g/100 g of oil), and α-linolenic C18:3 (9c12c15c 10.6 g/100 g of oil) acids. Nine out of 18 amino acids detected in leaves were essential amino acids (68.80 g/kg of dry matter leaves). Glutamic acid was found to be the major component of non-essential amino acids (25 g/kg of dry matter), followed by aspartic acid (16.2 g/kg of dry matter) and leucine (14.2 g/kg of dry matter). The element composition of leaves demonstrated the presence of: macroelements (K, P, S, Ca, Mg, Na), microelements (Zn, Fe, Cu, Mn, Cr, Se), and metals (Al, As, Cd, Ni, Hg, Pb). Potassium was the most abundant element in Schisandra chinensis leaves (10209 mg/kg of dry matter of leaves), followed by Ca, P, and Mg. The spectrophotometric assays enabled detecting phenolic compounds from three categories: polyphenols (44.32 mg galic acid equivalents/g of dry matter of leaves), total flavonoids (29.16 mg quercetin equivalents/g of dry matter of leaves) and phenolic acids (6.12 mg caffeic acid equivalents/g of dry matter of leaves) in Schisandra chinensis leaves. The antioxidant activity of S. chinensis leaves, as determined by DPPH^•, was at the level of 9.19 mg TEAC/g of dry matter of leaves, and 214 mg TEAC/g of dry matter of leaves (as determined by molybdenum reducing antioxidant power). The composition of Schisandra chinensis leaves suggest it to become an inexpensive novel plant source of functional foods, supplements, and as new ingredient in human diet.