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

Abstract

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 H 2 O 2 /Fe 2+ 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 H 2 O 2 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 H 2 O 2 /Fe 2+ —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.