Heliotropium procubens Mill: Taxonomic Significance and Characterization of Phenolic Compounds via UHPLC–HRMS- In Vitro Antioxidant and Enzyme Inhibitory Activities

The aim of the present study was the phytochemical analysis of the aerial parts of Heliotropium procumbens Mill., a herb from Boraginaceae plant family not previously studied. The methanol (ME) and aqueous extracts (WE) of the aerial parts were assayed for their total phenolic and flavonoid content and antioxidant properties, using free radical scavenging (DPPH, ABTS), reducing power (FRAP, CUPRAC), phosphomolybdenum and metal chelating assays. The extracts displayed considerable free radical scavenging activity against DPPH and ABTS radicals, with potential values of 46.88 and 68.31 mg TE/g extract for ME, and 93.43 and 131.48 mg TE/g extract for WE, respectively. Key clinical enzymes involved in neurodegenerative diseases AChE and BChE, diabetes (α-amylase and α-glucosidase) and skin whitening (tyrosinase) were also assayed. The phytochemical profile of the studied species was determined through UHPLC–HRMS, whereby 26 secondary metabolites were identified, three of which (luteolin-7-glucoside, lithospermic and rosmarinic acids) were isolated and structurally determined by NMR spectral means. H. procubens was found to harbor bioactive metabolites and could, hence, serve as a source of biological activities which could be further explored and exploited for potential applications.