Antioxidant and Biological Activities of Black Mulberry (Morus nigra L.) Fruit Depending on Altitude

Abstract

This study evaluated the effect of altitude on the content of polyphenols (total phenolics, flavonoids, anthocyanins, condensed tannins and gallotannins), antioxidant activity (hydroxyl radical scavenging activity, inhibition of lipid peroxidation, and ABTS and DPPH assays), antimicrobial activity and cytotoxic activity in black mulberry (Morus nigra L.) fruit extracts. The research was conducted in western Serbia at three locations of different altitude: location 1—Katrga (187 m), location 2—Trbušani (271 m) and location 3—Miokovci (493 m). The results indicated that altitude had a significant impact on the accumulation and synthesis of the tested parameters. At higher altitudes, the accumulation of total phenolics, flavonoids and anthocyanins increased. The highest values were determined at the location situated at an altitude of 493 m. By contrast, the accumulation of condensed tannins and gallotannins was most intensive at the lowest-altitude location (187 m). Microbial properties of extracts were examined using eight selected indicator strains. Minimum inhibitory concentrations varied from 19.53 to 156.25 µg/mL, depending on altitude. The fruit of black mulberries grown at 187 m had the highest antioxidant and cytotoxic activity compared to altitudes of 271 m and 493 m altitudes. The concentrations of extracts which inhibited 50% of cell growth for Hep2c, RD and L2OB at the lowest altitude were 18.55, 15.32, and 37.17 µg/mL, respectively. The present results showed that altitude had a significant effect on the synthesis and accumulation of polyphenols, and a strong effect on the antioxidant, antimicrobial and cytotoxic activities of black mulberry fruit.