Isolation and Characterization of N-Feruloyltyramine as the P-Selectin Expression Suppressor from Garlic (Allium sativum)

Garlic (Allium sativum) is a medicinal and culinary plant reported to have several positive health effects on cardiovascular-diseases, particularly via suppressing platelet activation. Therefore, active compounds inhibiting platelet activation were isolated from garlic extract using a P-selectin expression suppressing activity-guided fractionation technique. Garlic cloves were extracted with methanol, sequentially partitioned using ethyl acetate, and n-butanol. The ethyl acetate portion was fractionated using silica gel chromatography. The fraction with highest P-selectin expression suppressing activity was further purified using HPLC, and the compounds in the fraction were analyzed using MS,. MS/MS, and NMR spectroscopic methods. Using NMR spectroscopy, the compound with highest suppressing activity was confirmed as N-feruloyltyramine. At the concentration of 0.05 mu M, N-feruloyltyramine was able to suppress P-selectin expression on platelets by 31% (P < 0.016). Since COX enzymes are deeply involved in the regulation of P-selectin expression on platelets, potential effects of N-feruloyltyramine on COX enzymes were investigated. As expected at the concentration of 0.05,mu M, N-feruloyltyramine was found to be a very potent compound able to inhibit COX-I and -II enzymes by 43% (P < 0.012) and 33% (P < 0.014), respectively. N-Feruloyltyramine is likely to inhibit COX enzymes, thereby suppressing P-selectin expression on platelets.