Compositional and Nutritional Analyses of Samh (Mesembryanthemum cryptanthum) Flour: Integrated Phenolic, Metabolomic, Fatty Acid, and Antimicrobial Activity Profiling

Samh flour (SF), an underutilized traditional food product in Saudi Arabia, was evaluated for its nutritional composition, phytochemical profile, antioxidant capacity, mineral content, lipid constituents, polysaccharide-enriched fraction, and antimicrobial activity. SF was fractionated using hexane, ethyl acetate, butanol, and water. Proximate analysis showed that carbohydrates (63.38 g/100 g) and proteins (22.69 g/100 g) were the major nutritional components, together with low moisture and moderate fat contents. Targeted LC–MS/MS analysis showed that the ethyl acetate fraction contained the highest measured concentrations of several phenolic acids and flavonoids, particularly 3,4-dihydroxybenzoic acid, ferulic acid, naringenin, and kaempferol. This fraction also showed the lowest numerical DPPH IC50 value (6.22 ± 0.72 µg/mL) compared with the other SF fractions and the catechin standard (9.23 ± 1.83 µg/mL). ICP–OES analysis indicated appreciable concentrations of macroelements, including P, K, Mg, Na, and Ca, and trace elements such as Fe, Mn, and Zn, while the analyzed toxic elements were detected at low concentrations in the examined sample. General LC–MS screening of the ethyl acetate, butanol, and aqueous fractions provided tentative annotations of several metabolite classes, including amino acids, organic acids, nucleosides, phenolic derivatives, and flavonoid glycosides. GC–MS analysis of the hydrolyzed and derivatized polysaccharide-enriched fraction provided a provisional profile dominated by trimethylsilylated sugar derivatives. GC–MS screening of the methylated saponifiable fraction revealed selected peaks tentatively assigned as fatty acid methyl esters, including derivatives of palmitic, stearic, and linoleic acids, whereas the unsaponifiable fraction contained hydrocarbons and a tentatively annotated wax ester. The volatile fraction contained several unsaturated aldehydes and medium-chain hydrocarbons. Preliminary antimicrobial assays demonstrated inhibitory activity against selected bacterial and fungal strains, and MIC, MBC, and MFC endpoints were determined for the active fractions. Overall, this study provides a comprehensive chemical and biological characterization of SF and supports its potential as a functional food and a promising source of bioactive compounds.