Isolation of secondary metabolites from Syzygium aromaticum (L.) Merr. & L.M.Perry. (cloves), and evaluation of their biological activities.

Phytochemical investigation of dried flower buds of Syzygium aromaticum (L.) Merr. & L.M.Perry. (clove) led to the isolation and identification of fourteen known compounds, oleanolic acid ( 1 ), betulinic acid ( 2 ), para methyl benzoic acid ( 3 ), sabrinic acid ( 4 ) eucalyptolic acid ( 5 ), nigricin ( 6 ), 3- O - trans - para -coumaroylmaslinic acid ( 7 ), methyl maslinate ( 8 ), maslinic acid ( 9 ), 3, 4, 5-trimethoxy-3',4'- O , O -methylideneflavellagic acid ( 10 ), lantanone ( 11 ) 3,4,3'-trimethoxyellagic acid ( 12 ), 11-oxo-oleanolic acid ( 13 ), and β -sitosterol-3- O - β -D-glucopyranoside ( 14 ). Their structures were identified by 1 H NMR, 13 C NMR, Mass spectroscopic techniques, and comparison with the literature data. Compounds 3 , and 7-9 showed a strong mortality against root knot nematode, Meloidogyne incognita at 0.125% concentration after 72 hours (88-92% inhibition). Compound 4 showed a good anti-glycation activity with IC 50 = 142.0 ± 1.8  µ M when compared with standard, i.e. rutin (IC 50 = 54.59 ± 2.20  µ M). Compound 10 showed a comparable urease inhibitory activity (IC 50 = 26.1 ± 0.19  µ M) with the positive control thiourea (IC 50 = 24.5 ± 0.34  µ M).