ORGANIC AMENDMENT DEPENDENT MODULATION OF PHYTOCHEMICAL COMPOSITION, ANTIOXIDANT CAPACITY AND CARBOHYDRATE-HYDROLYZING ENZYME INHIBITORY ACTIVITY IN BRASSICA NIGRA AND TRIGONELLA FOENUM GRAECUM

Abstract

The development and growth of the plant, synthesis of secondary metabolites and production of biologically active substances could be associated with fertilization process. The application of organic amendment for nutrient management as an alternative to chemical fertilizers becomes more and more popular.The aim of the current study was the analysis of phytochemical composition and certain biological activities of Brassica nigra and Trigonella foenum graecum in organic amendment and chemical fertilizer cultivation. The plants were cultivated with two different fertilizers, collected after 15 days cultivation period, dried and powdered. Then the methanolic extracts were prepared, and the analysis of phytochemicals, total phenols, total flavonoids, tannins content, DPPH radical scavenging activity, FRAP assay, α amylase and α-glucosidase inhibition activities was performed. Furthermore, the analysis of volatile and semi-volatile compounds was carried out by GC-MS.The highest content of total polyphenols (TPC – 57.3 mg/g), total flavonoids (TFC – 58.5 mg/g) and total tannins (53.6 mg/g) were revealed for B. nigra plants fertilized by organic amendment, while the lowest content (29.3, 28.9 and 28.4 mg/g) for B. nigra plants fertilized chemically. T. foenum-graecum plants contained higher amounts of TPC, TFC and TTC during fertilization by organics comparing with those fertilized by chemical. During the antioxidant experiments, the differences according to the type of fertilization were found, when plants fertilized inorganically had lower IC₅₀ value of DPPH in both types of plants. Also, the α-amylase and α-glucosidase inhibitory experiments confirmed the inhibition of these plants. As it can be seen from the results, the fertilization affects the phytochemicals and biological activity of both plants.