Scanning Electron Microscopy Analysis, Fourier Transform Infrared Spectrum Structure Profile Characterisation, and in vitro Biological Effect of Salvia officinalis L. Phytocompounds

Abstract

Background: The aims of this research is to investigate the potential activity of Salvia officinalis and various hairs responsible of secretion of essential oil. In Tunisia, biological activity of Salvia officinalis is poorly recorded. Salvia leaves contain various types of hairs (glandular and non-glandular). Methods: The investigation of different trichomes were carried out by scanning electron microscope (SEM) apparatus. Antiradical potential were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assay. Antimicrobial activity was analysed using disc diffusion assay. The extracts of Salvia officinalis (SvOf), showed the following order of richness in phenolic contents: methanolic (70.76 mg GAE/g DW), aqueous (43.76 mg GAE/g DW) and infusion (9.42 mg GAE/g DW). The methanolic fraction records the highest levels of flavonoids (77 mg QE/g DW) compared with the aqueous extracts (33.19 mg EQ/g DW) and infusion (26.25 mg EQ/g DW). ME-SvOf showed higher value of free radical scavenging activity towards DPPH free radical and ferric reducing power. Results: The results revealed that main bioactive constituents in the methanolic fractions of sage leaves generally exhibited higher antibacterial effects. Overall, sage phytocompounds constitute a promising approach for the treatment of infectious diseases. Discussion: Functional groups detected in S. officinalis by Fourier transform infrared spectrophotometer (FT-IR) were mainly phenols, saccharides, amine and aromatic (Ar-H). Conclusion: Antiradical and antibacterial activities of Salvia officinalis are mainly due to phenolic content and other bioactive compounds. Non-glandular hairs are the most important trichomes in the Salvia leaves.