Composition of Bioactive Compounds in American Skullcap (Scutellaria Lateriflora L.) Leaves as Influenced by Mineral Fertilization

Abstract

American skullcap is a medicinal plant rich in bioactive compounds and possesses excellent therapeutic values. There is limited information on the cultivation of plant materials with mineral fertilization, as supply is mostly dependent on natural habitats. In this study, leaf extracts obtained from plants that were cultivated with different mineral fertilizer rates were analyzed for total phenolic content (TPC), total flavonoids content (TFC), condensed tannins (PAC), and antioxidant activities by 2,2-diphenyl-1-picrylhydarazy (DPPH), Nitric Oxide and Hydrogen peroxide were evaluated for aqueous and methanol leaf extracts of different fertilizer treatments. The effect of the fertilizer treatments was significant (P<0.05) among treatment combinations. The post-flowering stage had the highest concentration of TPC (41.65%), pre-flowering (33.83%), and the least at the flowering stage (24.52%). A higher concentration of tannins was recorded at the pre-flowering stage (38.5%), post-flowering stage (31.2%), and the least at the flowering stage (30.3%). However, for the TFC, a higher concentration was recorded at the post-flowering stage (38.2%), followed by the pre-flowering stage (34.2%) while the least TFC was recorded at the flowering stage (27.6%). Also, treatments with lower amounts of supplementary phosphorous (P1=213kg/ha) produced higher concentrations of bioactive compounds across all the phenological stages, with methanol extract producing a higher concentration than aqueous extract.

Keywords: antioxidants, medicinal plants, phytochemicals, Plant extracts, Scutellaria lateriflora