Inhibitory effect on human platelet aggregation and coagulation and antioxidant activity of C. edulis Ker Gawl rhizome and its secondary metabolites

Ethnopharmacological relevance: Although Canna edulis Ker Gawl rhizome has been used in Traditional Vietnamese Medicine to prevent and treat heart diseases without thorough scientific evidence, limited intensive search for the bioactivities and useful substances has been done.

Aim of the study: This study aims to investigate the antiplatelet aggregation, anticoagulant and antioxidant activity of extracts from C. edulis rhizome, separate and purify its compounds from the most active fraction and evaluate the antiplatelet aggregation, anticoagulant and antioxidant activity of isolated compounds.

Materials and methods: C. edulis rhizome was extracted with ethanol, then fractionated with n-hexane, ethyl acetate and water. The inhibitory effect on adenosine diphosphate- and collagen-induced human platelet aggregation was evaluated. Prothrombin time, activated partial thromboplastine time and thrombine time were measured to examine the anticoagulant activity. The free radical scavenging ability was assessed with DPPH and ABTS assays. The fraction that showed the most active was used to separate and purify compounds. The structures of compounds were elucidated by NMR and MS spectroscopic methods. Isolated compounds were also tested for antiplatelet, anticoagulant and antioxidant activity.

Results: The ethyl acetate fraction showed the most potent antiplatelet aggregation, anticoagulant and antioxidant activity. Subsequent fractionation of this active fraction resulted in the isolation of seven known compounds: 5-hydroxy-6-methyl-2H-pyran-2-one (1), epimedokoreanone A (2), nepetoidin B (3), ferulic acid (4), caffeic acid (5), hydroxytyrosol (6), and 1H-indole-3-carboxaldehyde (7). Previous studies reported the antiplatelet, anticoagulant and antioxidant activity of ferulic acid (4), caffeic acid (5) and hydroxytyrosol (6) and the antioxidant activity of nepetoidin B (3). This study demonstrated that both epimedokoreanone A (2) and nepetoidine B (3) also exhibited good antiplatelet effect and epimedokoreanone A (2) also had effective anticoagulant and antioxidant activity, while 5-hydroxy-6-methyl-2H-pyran-2-one (1) showed weaker antiplatelet and antioxidant activity but no anticoagulant effect.

Conclusions: This is the first experimental study to demonstrate the potent dose-dependent antiplatelet aggregation, anticoagulant and antioxidant activity of C. edulis rhizome and its pure compounds, supporting the traditional use of this plant for the treatment of heart diseases. The C. edulis rhizome is a potential source of bioactive compounds or functional food for treatment and/or prevention of heart- and oxidative stress-related diseases and its bioactive compounds are good candidates for drug development of anti-thrombosis and antioxidant agents.

Keywords: Anticoagulant; Antioxidant; Antiplatelet; Canna edulis Ker; Phytochemicals.