Assessment of the antithrombotic properties of polar lipids of beer and brewing industry by-products.

This study investigated the in vitro antithrombotic properties of the lipids extracted from malted grain (MG), brewer’s spent grain (BSG), raw hops (RWHP), spent hops (SPHP), wort, and beer. Total lipids (TL) were extracted according to the Bligh & Dyer method and further separated into total polar lipid (TPL) and total neutral lipid (TNL) using a modified counter-current distribution method. The TPL of the beer was further fractionated by TLC and isolated bands were extracted. The antithrombotic activities of the TL, TPL and TNL of the MG, BSG, RWHP and SPHP were analysed in vitro for their ability to inhibit platelet-activating factor (PAF) induced aggregation in human platelets. Seven bands extracted by preparative TLC of the beer TPL were also tested for the ability to inhibit PAF induced platelet aggregation. This study demonstrated that the TPL extracts were the most bioactive with the exception of BSG as the TL displayed potent antithrombotic activity. The wort and beer TPL displayed the most potent inhibitory activity against PAF induced platelet aggregation. However, the beer TPL possessed the strongest inhibitory activity against PAF with the lowest IC50 value (7.8 ± 3.9 μg) and it was noted that fermentation of the wort increased the antithrombotic activity, which may warrant further investigation. The TLC bands 2 and 3 of the beer TPL exhibited potent inhibitory activity against PAF, which may be due to the presence of phenolic compounds. The fatty acid composition of the TPL extracts of all samples were analysed by gas chromatography-mass spectrometry (GC-MS). The GC-MS analysis of the TPL found that the wort and beer shared similar fatty acid compositions. The findings of this study provide new information into the effect of fermentation on the fatty acid composition and antithrombotic properties of beer. Further structural and functional studies are required to identify the exact compounds responsible for the observed biological activity of the TPL extracts.