The evaluation of phenolic compounds and antioxidant activity in the raw materials of black nightshade (Solanum nigrum L.).

The aim: to investigate the quantitative composition of phenolic compounds, flavonoids and phenolic acids, and their antioxidative activity from black nightshade (Solanum nigrum L.) collected from various places in Lithuania. Objectives: 1) To select the optimal conditions for extracting the highest amounts of phenolic compounds from experimental raw materials of black nightshade (S. nigrum). 2) To investigate the distribution of phenolic compounds, phenolic acids and flavonoids by spectrophotometric method and it’s variation in the black nightshade plant raw material (S. nigrum). 3) Using the DPPH and ABTS methods to evaluate the antiradical activity of plant ethanolic extracts of black nightshade (S. nigrum). 4) Using the FIC and FRAP methods to evaluate the chelating and radical properties of black nightshade (S. nigrum). 5) Determine the correlation between the total amounts of phenolic compounds, phenolic acids and flavonoids in black nightshade raw materials and the antioxidant activity of their extracts. Research methodology: The raw materials used for the study were Solanum nigrum (ripe fruit, unripe fruit, stems and leaves). Extraction method – ultrasound agitation, extrahent - 60% ethanol, extraction time - 5 min, temperature - 30 ° C. The total amount of phenolic compounds is determined by the Folin-Ciocalteu method, and the results are expressed in gallic acid equivalents (GE) (mg/g). The general method for determining flavonoid content is the method using AlCl3 and methenamine reagents, the results obtained being expressed in routine equivalents (RE) (mg/g). Arnow reagent was used to determine the total amount of phenolic acids and expressed as chlorogenic acid (mg/g). The antioxidant activity of the extracts was assessed by FIC, DPPH, ABTS and FRAC spectrophotometric methods. Results and conclusions: S. nigrum plant raw materials are characterized by the variability of the quantitative composition of total phenolic compounds, phenolic acids and flavonoids. Their distribution depends directly on the morphological part of the plant and on the cenopopulation. The highest amounts of phenolic compounds and phenolic acids were found in ripened berries and leaves of S. nigrum, and the highest amounts of flavonoids in leaves. It was found that S. nigrum‘s ripened berries and leaf extracts had the strongest ability to bind free radicals in both in vitro systems (DPPH and ABTS). extracts. Statistical analysis of the obtained results revealed medium and statistically significant correlation between total phenolic compounds, phenolic acids and flavonoids in S. nigrum raw materials and antioxidant effects of their extracts