Prickly pear seed is a source of the most expensive oil in the world, which is rich in vitamins and polyunsaturated fatty acids. Its extraction generates a large quantity of press cake. These two by-products need to be valued. The current study aimed to assess the fatty acid composition of oil and the phytochemical composition of press cake. In addition, the antioxidant and the inhibition of thermal protein denaturation effects of both Algerian seed by-products were evaluated with their inhibitory action against the activities of urease, tyrosinase, α-amylase, and cholinesterase enzymes. The GC MS analysis result revealed the richness of our oil in linoleic (74%) and palmitic (13%) acids methyl esters, respectively. The chemical composition of press cake was characterized by a high value of dry matter (94.94 ± 0.05%), especially the carbohydrates (85.13 ± 0.94%). The results of antioxidant activity presented by IC₅₀ and A_0.5 ranged from 7.51 ± 0.03 to 88.10 ± 0.92 µg/mL. Furthermore, the IC₅₀ values were 40.19 ± 1.21 and 61.18 ± 0.03 µg/mL in thermal protein denaturation assay, and ranging from 22.97 ± 0.72 to 385.99 ± 0.27 µg/mL for the inhibition of enzymatic activities. These results indicate that the studied oil can be one of the strongest oils for its impressive effects and also encourage us to reuse its press cake in feed livestock.

Euphorbia bupleuroides Desf. is an underexplored Algerian medicinal plant of the family Euphorbiaceae. In the present study, we are interested in the phytochemical composition, antioxidant potential, photoprotective effects, and enzyme inhibitory activities of five crude extracts obtained from E. bupleuroides namely hydroethanolic (HAE), aqueous (Aq), hexane (Hex), ethyl acetate (EtOAc), and n-butanol (n-BuOH). The hydroethanolic extract (HAE) showed the highest total phenolic (142 µg GAE mg–1) and flavonoid (90 µg QE mg–1) contents, correlating with its superior antioxidant performance across DPPH, ABTS, and other in vitro assays (IC50 = 14.07 ± 0.07 – 175.97 ± 2.35 µg mL⁻¹). All extracts exhibited significant radical-scavenging capacity, contributing to notable sun protection potential, with SPF values of 40.38 ± 0.38, 40.09 ± 0.12, 40.06 ± 0.77 and 34.79 ± 1.14 for the ethyl acetate (EtOAc), hydroethanolic (HAE), aqueous (Aq) and n-butanolic (n-BuOH) extracts, respectively. In enzymatic assays, the extracts demonstrated moderate inhibition of butyrylcholinesterase activity, with IC50 ranging from 140 to 199 µg mL–1, but only weak acetylcholinesterase inhibition reaching IC50 value of 575.49 µg mL–1. The hexane extract (Hex) exhibited selectively moderate inhibition of α-amylase (IC50 = 343.61 ± 1.95 µg mL–1). The extracts also displayed moderate activity against tyrosinase or urease. Overall, these results highlight E. bupleuroides as a promising source of phenolic-rich bioactive extracts with marked antioxidant and selective enzyme inhibitory properties, supporting further phytochemical and biological investigations to identify active secondary metabolites, especially phenolic compounds and flavonoids, and assess their pharmacological potential for medical and pharmaceutical purposes.