Browsing by Author "Kontek, Bogdan"

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    Comparative phytochemical, antioxidant, and hemostatic studies of leaf and stem extracts of Rhazya stricta Decne. in human plasma and human peripheral blood mononuclear cells in vitro
    (Frontiers, 2026-05-11) Hamed, Arafa I.; Mohamed, Amal A. A.; Ben Aissa, Mohamed Ali; Kontek, Bogdan; Kluska, Magdalena; Woźniak, Katarzyna; Kowalczyk, Mariusz; Kowalska, Iwona; Oleszek, Wiesław; Olas, Beata
    Introduction: Rhazya stricta Decne. is considered an important medicinal plant that is rich in secondary metabolites containing anticancer alkaloids. Several indole alkaloid classes have been identified from the various parts of R. stricta, but the cytotoxic potentialities of only a few of these metabolites are known.Methods: In this study, an applied analytical method was used to determine the alkaloids in R. stricta from the stem (RS) and leaf (RL) and their extracts.Results and Discussion: This study tentatively elucidated 10 new compounds of indole alkaloids from the various parts of R. stricta. Among them, six alkaloidal glycosides had not been detected in natural resources. This investigation also examined the in vitro protective results of the four R. stricta stem (A–D) and leaf (A′–D′) extracts, each having a different group of compounds—indole alkaloids, against oxidative stress activated by H2O2/Fe2+ in human plasma in vitro. In addition, we estimated the effect of these plant extracts on DNA fragmentation in human peripheral blood mononuclear cells (PBMCs). Another aim of these in vitro experiments was to determine the result of A–D and A′–D′ on selected hemostatic parameters of human plasma, such as the activated partial thromboplastin time, prothrombin time, and thrombin time, and on the viability of PBMCs. Based on our results, we demonstrate for the first time that tested extracts of the leaves and stems of R. stricta containing different indole alkaloid compounds (especially two tested preparations from R. stricta leaf—C′ and D′) are good antioxidant in vitro models, depending on the dosage, and they may have some promising actions in vivo. For example, we observed a significant difference in the level of DNA damage induced by H2O2 in the experiment with A–D and A′–D′. Two tested extracts from R. stricta leaf (C′ and D′, at all concentrations used) were also found to protect plasma against H2O2/Fe2+—induced lipid peroxidation. In addition, preparation C′ does not induce cytotoxicity. The potential of the metabolomics of extract C′ may be correlated to the presence of rhazisidine, secamine, and their derivatives.
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    Phytochemical analysis of the extract from berries of Schisandra chinensis Turcz. (Baill.) and its anti-platelet potential in vitro
    (MDPI, 2025-01-25) Sławińska, Natalia; Kontek, Bogdan; Żuchowski, Jerzy; Moniuszko - Szajwaj, Barbara; Białecki, Jacek; Zakrzewski, Kamil; Bogusz, Paulina; Stochmal, Anna; Olas, Beata
    Schisandra chinensis Turcz. (Baill.) is a dioecious vine belonging to the Schisandraceae family. Its berries show beneficial activities, including cardioprotective, antioxidant, and anti-inflammatory. We examined the chemical content of S. chinensis berry extract and its antiplatelet potential in vitro. The antiplatelet activity assays included measurements of thrombus formation in full blood (with Total Thrombus-formation Analysis System) and platelet activation and adhesion. We also assessed the extract’s effect on coagulation times in human plasma and its cytotoxicity toward blood platelets based on extracellular lactate dehydrogenase activity. The most important constituents of the extract were dibenzocyclooctadiene lignans; schisandrin was the dominant compound. S. chinensis berry extract at the concentration of 50 μg/mL inhibited thrombus formation by approximately 15%. The adhesion of unstimulated and thrombin-activated blood platelets to collagen was inhibited by all used concentrations of the extract (0.5–50 μg/mL), while the adhesion of adenosine diphosphate (ADP)-activated platelets to fibrinogen was inhibited only by the concentrations of 10 and 50 μg/mL. The extract also inhibited the exposition of the active form of GPIIb/IIIa on the surface of platelets stimulated with 10 μM ADP (at 0.5–50 μg/mL) and 20 μM ADP (at 50 μg/mL). The exposition of P-selectin was inhibited only by the extract at the concentrations of 5–50 μg/mL in platelets stimulated with 10 μg/mL collagen. Moreover, the extract was not cytotoxic toward blood platelets. This indicates that S. chinensis berries hold promise as new antiplatelet agents, but more studies are needed to determine their mechanisms of action and in vivo efficiency.