Carbohydrate Composition and Antioxidant Activity of Certain Morus Species

The aim of the current study was to investigate the carbohydrate composition, total phenolic content and in vitro antioxidant activities of 70 % (v/v) ethanol extracts obtained from fruits and leaves of three Morus species: white mulberry (Morus alba), black mulberry (Morus nigra) and red mulberry (Morus rubra) grown in Bulgaria. The carbohydrate content was determinated by spectrophotomeric, TLC and HPLC-RID methods. The total phenolic content was analyzed by Folin–Ciocalteau method. The antioxidant activities of above mentioned extracts were evaluated by DPPH and FRAP assays. From the obtained results, monosaccharides fructose and glucose were found to be the main sugars in all investigated extracts, as their content reached to 3.0 g/100 g fw in fruits and 0.6 g/100g fw in leaves. M. alba and M. rubra fruits were evaluated as a natural source of prebiotic, due to the presence of 1-kestose, nystose and inulin. The absence of sucrose in all mulberry fruit extracts was also established. The total phenolic content was reported to be the highest in black and red mulberry leaves, as their values reached up to 2 mg GAE/g fw. The extracts from M. nigra leaves demonstrated the highest antioxidant activity for both assays: for DPPH were 10.9 mM TE/g fw and for FRAP – 6.0 mM TE/g fw, respectively. The current research was the first comprehensive study for detailed analysis of carbohydrate composition and antioxidant properties of three mulberry species grown in Bulgaria. Therefore, mulberry fruits and leaves could be assumed as a rich source of biologically active substances with great importance for human nutrition.