CHEMICAL AND BIOLOGICAL INVESTIGATION OF SOME SPECIES OF SALVIA

One of the most significant families of herbaceous plants is the Lamiaceae. It includes a large number of species with noteworthy biological and medicinal uses. The genus Salvia is of particular importance due to its production of secondary metabolites such as phenolics, terpenoids, flavonoids and volatile compounds, which are of significant value in the pharmaceutical, food and perfumery industries. An emerging area of interest is the potential of plant extracts as natural alternatives to mitigate agricultural losses caused by phytopathogenic fungi and bacteria. My thesis work mainly focuses on investigating the phytochemical composition and biological activities of various Salvia species. This study aims to contribute to this field by exploring the bioactive potential of Salvia spp. for environmentally friendly agricultural solutions. The biomass of Salvia spp. was subjected to surface extraction with dichloromethane and purified by applying different chromatographic techniques. The phytochemical profile was studied by LC-MS and NMR analysis. The crude extracts were evaluated for their antimicrobial and insecticidal potential. Exudates of S. discolor and S. karwinskii showed an abundance of clerodane-type diterpenoids. The crude extract demonstrated a broad spectrum of antimicrobial activity against different phytopathogens. Moreover, surface extracts of S. buchanani, S. corrugata, S. discolor, S. karwinskii, and S. namaensis were evaluated against an invasive pest Tuta absoluta. All extracts showed significant mortality rates, in particular, S. discolor and S. karwinskii exhibited strong antifeedant and insecticidal effects. In addition, biotechnological approaches were used to develop an in vitro micropropagation protocol and establish hairy roots (HRs) for S. oxyphora. Extracellular vesicles (EVs) were successfully isolated from the liquid culture of HRs. EVs are mixtures of heterogeneous populations of structures with a wide size distribution (30-1000 nm). Plant-derived EVs show great promise as next-generation drug delivery systems, as they can concentrate and transport various bioactive molecules to human cells. These findings highlight the versatility and potential of Salvia species as a natural, sustainable resource for controlling phytopathogens and pests. By advancing our understanding of their bioactive compounds, this research contributes to developing environmentally friendly solutions to agricultural challenges. It highlights the broader applications of plant-derived products in science and industry.