Scientia Pharmaceutica

Hydroethanolic Cucurbita pepo seed extracts are traditionally used for alleviating lower urinary tract symptoms (LUTS), yet their mechanisms remain unclear. Adenosine, a purine nucleoside involved in neuromodulation and smooth muscle relaxation, was recently identified in C. pepo seeds. Since A₁ adenosine receptors (A₁AR) suppress parasympathetic bladder overactivity by inhibiting acetylcholine (ACh) release, we investigated to which extent purines from pumpkin seed extracts contribute to A₁AR activation. Complementary antioxidant capacity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Three hydrophilic seed extracts containing different adenosine levels (0.60–1.18 mg/g dw) were evaluated for agonist activity using a cAMP inhibition assay. The most active extract showed an EC₅₀ of 40.22 µg/mL. Selective removal of adenosine shifted the dose–response curve rightward, while further elimination of an adenosine derivative increased the EC₅₀ to 212.10 µg/mL, confirming adenosine as the principal active compound. Guanosine and inosine did not exhibit A₁AR agonist or allosteric effects. All samples exhibited measurable but weak antioxidant activity (IC₅₀ = 1.02–4.19 mg/mL), consistent with their low total phenolic content. These findings underscore the importance of accounting for naturally occurring agonists in plant extracts to avoid overestimating receptor-mediated effects in vitro which are not translatable in vivo.

We aimed to investigate the interaction mechanism of transport protein Human serum albumin (HSA) with a synthesized compound, QP-11, with tested antimalarial properties to monitor the changes in the protein because of QP-11 binding. The interaction between the antimalarial compound QP-11 and HSA was thoroughly investigated through a multidimensional approach, utilizing UV-VIS spectroscopy, fluorescence, time-resolved fluorescence, and CD (Circular dichroism), alongside molecular docking techniques. Our findings unveiled a robust 1:1 binding pattern, signifying a strong affinity between QP-11 and HSA. Employing static quenching, evidenced by time-resolved fluorescence spectroscopy, QP-11 was observed to induce fluorescence quenching of HSA, particularly binding to subdomain IIA. Thermodynamic parameters indicated that van der Waals forces and hydrogen bonding predominantly facilitated the binding, with increased temperature compromising complex stability. The 3D fluorescence and CD results demonstrated QP-11-induced conformational changes in HSA. Both experimental and in silico analyses suggested a spontaneous, exothermic binding reaction. The profound impact of the QP-11–HSA interaction underscores the potential for QP-11 in antimalarial drug development, encouraging further exploration for dose design and enhanced pharmacodynamic and pharmacokinetic properties.

This study aimed to characterize the chemical composition and evaluate the biological activities of the aerial parts of Alkanna corcyrensis Hayek (AC), an endemic Greek species not previously studied. Phytochemical analysis of the methanolic extract was performed using UHPLC-ESI-Q-TOF–MS/MS combined with molecular networking analysis. Additionally, the total phenolic content (TPC) and total flavonoid content (TFC) were determined. Chromatographic separations were carried out to isolate major compounds, and the antioxidant capacity, along with enzyme inhibitory activity, was assessed. The analysis led to the tentative identification of 86 compounds, including 67 phenolic compounds (mainly caffeic acid derivatives and flavonoid glycosides), 10 pyrrolizidine alkaloids of trachelanthamidine, platynecine, and retronecine types, and nine organic and fatty acid derivatives. Among these, one flavonol glycoside (kaempferol-O-malonyl methyl ester hexoside) and three pyrrolizidine alkaloids (9-sarracinoyl-trachelanthamidine/isoretronecanol, retronecine-pentoside, and trachelanthamidine/isoretronecanol-hexoside) were reported for the first time. The extract exhibited high TPC (74.45 mg GAE/g extract) and TFC (46.66 mg GAE/g extract). Chromatographic separations resulted in the isolation of five major metabolites, namely rosmarinic acid, danshensu, kaempferol-3-O-glucoside, kaempferol-3-O-galactoside, and quercetin-3-O-glycoside. Biological evaluation revealed considerable antioxidant activity and inhibitory effects against α-glucosidase (6.65 mmol ACAE/g extract). Overall, this study highlights the remarkable phytochemical diversity and richness of AC among alkanet species and demonstrates its promising antioxidant potential, laying the foundation for further investigations towards its future exploitation.