Objectives: Garlic (Allium sativum) has a well-established reputation as a protective agent against cardiovascular disease, while nearly nothing is known about its cousin Allium ursinum. The aim of this study was to evaluate the antiaggregatory mechanism of garlic and to compare the effects of A. ursinum and A. sativum. Methods: In a prospective study, extracts were prepared from A. sativum powder made from fresh A. sativum bulbs and fresh A. ursinum leaves by maceration. The extracts were characterized by thin layer chromatography. Their in vitro effects on human platelet aggregation were examined by light transmission aggregometry after induction by adenosine diphosphate (ADP), collagen, A23187, epinephrine and arachidonic acid (ARA) in platelets from healthy volunteers. Results:A. ursinum and A. sativum exert similar antiaggregatory effects: they inhibit platelet aggregation induced via the ADP pathway and to a lesser extent aggregation induced by epinephrine, whereas ARA-, collagen- and A23187-induced aggregation was not affected. It became clear that the alcoholic extract of A. ursinum is the potent form, while the aqueous extract exerted an unspecific activity. The effects were strictly dose related. A. ursinum and A. sativum extracts exhibited similar potencies. Conclusion: Both A. ursinum and A. sativum exert antiaggregatory effects. Garlic extracts are acting by inhibition of the ADP pathway; their mechanisms of action are comparable to that of the clinically used drug clopidogrel. The pharmacologically active component of the extracts appears to be lipophilic rather than hydrophilic, but the precise chemical substance is still unknown. This is the first report on the antiplatelet activity of A. ursinum.

Aims: We wanted to investigate the possible antithrombotic effects and elucidate the chemical identity of the active principles involved in inhibitory effects against adenosine diphosphate (ADP)-induced aggregation of human platelets by wild garlic, Allium ursinum L. Methods: For this purpose, a bioassay-guided isolation procedure was used followed by spectrometric identification of pure active compounds. For the bioassay, blood was taken from healthy human volunteers and platelet-rich plasma was prepared for turbidimetric platelet aggregation tests. Platelet-rich plasma, stimulated with 20 µmol/l of ADP, was treated with extracts of different polarities, fractions and isolated single compounds from A. ursinum. The extracts were investigated by thin-layer chromatography (TLC), HPLC, mass spectroscopy, electrospray ionization mass spectrometry (ESI-MS) and 1/2-dimensional ¹H/¹³C-nuclear magnetic resonance (NMR) spectroscopic techniques. Results: Fresh A. ursinum leaves were extracted with ethanol, which was the potent form that effectively inhibited ADP-induced aggregation of human platelets. This ethanolic extract was subjected to liquid-liquid partition. Whilst the aqueous phase, containing the moiety of cysteine sulphoxide and thiosulphinate derivatives, showed only weak activity on platelet aggregation, the ethyl-acetate and particularly the chloroform partitions showed the highest aggregation-inhibiting potency. Thus, in our bioassay, the effects of alliins/allicins could be neglected. The chloroform phase, possessing the strongest activity, was separated into 28 fractions by gradient-elution open column chromatography on silica gel. The most active fractions 11–17 were separated again, yielding 10 subfractions. This afforded 1,2-di-O-α-linolenoyl-3-O-β-D-galactopyranosyl-sn-glycerol and β-sitosterol-3-O-β-D-glucopyranoside, the structures of which were determined by ESI-MS and 1/2-dimensional ¹H/¹³C NMR spectroscopic techniques. Furthermore, the minute amounts of volatile oil of A. ursinum leaves obtained by steam distillation according to Ph. Eur. could be evaluated as a third aggregation-inhibiting principle. Conclusion: In our study, for the first time, 2 active, non-sulphur-containing constituents of wild garlic, namely a galactolipid and a phytosterol, could be identified exhibiting inhibitory action on ADP-induced aggregation in human blood platelets. As a major constituent, the galactolipid, 1,2-di-O-α-linolenoyl-3-O-β-D-galactopyranosyl-sn-glycerol, not yet found in Allium sp., appears as a new, highly useful marker substance for A. ursinum drugs, or their pharmaceutical or food preparations, as shown by our orientating TLC analyses.

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