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 ß-sitosterol-3-O-ß-D-glucopyranoside (14). Their structures were identified by 1H NMR, 13C 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 IC50 = 142.0 ± 1.8 µM when compared with standard, i.e. rutin (IC50 = 54.59 ± 2.20 µM). Compound 10 showed a comparable urease inhibitory activity (IC50 = 26.1 ± 0.19 µM) with the positive control thiourea (IC50 = 24.5 ± 0.34 µM).

Anti-glycation properties of Illicium verum Hook. f. fruit in-vitro and in a diabetic rat model.

BACKGROUND: Chronic hyperglycemic triggers the non-enzymatic glycation of biomolecules, resulting in the production of advanced glycation endproducts, that lead to several micro- and macrovascular complications. Therefore, the discovery of new, effective, and safe anti-glycation agents is an important need. One of the best choices for the management of diabetes is to use complementary and alternative medicinal therapies. Therefore, the present study was designed to evaluate the anti-glycation activity of ethanolic extract of Illicium verum Hook. f. (Star anise, a frequently used spice and medicinally important herb). METHODS: The anti-glycation activity of ethanolic extract of Illicium verum Hook. f. was determined by using both in-vitro and in-vivo assays. HSA-fructose glycation model was employed to assess the in-vitro inhibition of protein glycation, additionally cross-linked AGEs (formed by incubating lysozyme with fructose) were assessed by SDS polyacrylamide gel electrophoresis. Dual inhibitory mechanisms, i.e., antioxidant and metal chelating activities, were also evaluated by using DPPH, ABTS, and Fe (II)-chelation assays. Acute toxicity of I. verum extract was also performed (by administrating different doses i.e. 2,000, 1,500, 1,000, and 500 mg/kg of body weight). Finally, in-vivo anti-glycation potential was evaluated by 7 weeks of administration of I. verum extract in streptozotocin-induced diabetic rats. RESULTS: In HSA-fructose glycation model, extract of I. verum showed a good inhibitory activity with IC50 value of 0.11±0.001 mg/mL, as compared to the standard inhibitor, rutin (IC50 = 0.02±0.01 mg/mL). Extract of I. verum showed inhibitory activity in DPPH, and ABTS radical scavenging assays with IC50 values of 130±1.0, and 57±2.0 µg/mL, respectively, while it was found to be inactive in the Fe+2-chelation assay. The extract was found to be non-toxic, and reduce the elevated blood glucose, urea, lipid, liver function parameters, and renal AGEs levels in streptozotocin-induced diabetic rats. CONCLUSIONS: These results suggest that I. verum supplementation might help to reduce the burden of AGEs, and may have potential in preventing diabetes-associated complications.