METHOD: Literature search was performed within the PubMed, ScienceDirect.com and Google Scholar.
RESULTS: The presence of proline at the C-terminal tripeptide of ACE inhibitor can competitively inhibit the ACE activity. The effects of other amino acids are less studied leading to difficulties in predicting potent peptide sequences. The broad specificity of the enzyme may be due to the dual active sites observed on the somatic ACE. The inhibitors may not necessarily competitively inhibit the enzyme which explains why some reported inhibitors do not have the common ACE inhibitor characteristics. Finally, the in vivo assay has to be carried out before the peptides as the antihypertensive agents can be claimed. The peptides must be absorbed into circulation without being degraded, which will affect their bioavailability and potency. Thus, peptides with strong in vitro IC50 values do not necessarily have the same effect in vivo and vice versa.
CONCLUSION: The relationship between peptide amino acid sequence and inhibitory activity, in vivo studies of the active peptides and bioavailability must be studied before the peptides as antihypertensive agents can be claimed.
METHODS: Well diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays were used to test antibacterial activity against four pathogenic bacteria namely Staphylococcus aureus, Escherichia coli, Bacillus cereus, and Pseudomonas aeruginosa. DPPH (2, 2-diphenyl-1- picrylhydrazyl) and superoxide dismutase (SOD) assays were used to evaluate antioxidant activity. HPLC and gel filtration were used for purification of the peptides. Scanning electron microscope was applied to investigate the mode of attachment of the peptides on target microbial membranes.
RESULTS: Aqueous extraction of the mixture showed no inhibition zones against all the test bacteria. Mean diameter of inhibition zones for ethanol extraction of this mixture attained 8.33 mm, 7.33 mm, and 6.33 mm against S. aureus at corresponding concentrations of 500, 250 and 125 mg/ml while E .coli showed inhibition zones of 9.33 mm, 8.00 mm and 6.66 mm at the same concentrations. B. cereus exhibited inhibition zones of 11.33 mm, 10.33 mm and 10.00 mm at concentrations of 500, 250 and 125 mg/ml respectively. The peptide extract demonstrated antibacterial activity against S. aureus, E. coli and B. cereus. The MIC and MBC values for ethanol extracts were determined at 125 mg/ml concentration against S. aureus and E. coli and B. cereus value was 31.5 mg/ml. MIC and MBC values showed that the peptide extract was significantly effective at low concentration of the Australian plant mixture (APM). Phenolic compounds were detected in hot aqueous and ethanolic extracts of the plant mixture. Hot aqueous, ethanol and peptides extracts also exhibited antioxidant activities.
CONCLUSIONS: It was concluded that APM possessed good antibacterial and antioxidant activities following extraction with different solvents. The results suggest that APM provide a new source with antibacterial agents and antioxidant activity for nutraceutical or medical applications.
METHODS: Adult female SD rats were injected with 2 mg/kg 17β-oestradiol (E2) to synchronize their oestrous cycle. A day after injection, uteri were removed for in-vitro contraction studies. The dose dependent effect of Ficus deltoidea aqeous extract (FDA) on the tension produced by the isolated rat's uteri was determined. The effects of atropine (2×10(-8) M), atosiban (0.5 IU), THG113.31 (10 μM), oxodipine (0.25 mM), EDTA (1 mM), 2-amino-ethoxy-diphenylborate (2-APB) (40 mM) and thapsigargin (1 mM) on the maximum force of contraction (Emax) achieved following 2 mg/ml FDA administration were also investigated.
RESULTS: FDA induced in-vitro contraction of the isolated rat's uteri in a dose-dependent manner. Administration of atropine, atosiban and THG113.31 reduced the Emax with atosiban having the greatest effect. The Emax was also reduced following oxodipine and EDTA administration. There was no significant change observed following 2-APB administration. Thapsigargin, however, augmented Emax.
CONCLUSIONS: FDA-induced contraction of the isolated rat's uteri is mediated via multiple uterotonin receptors (muscarinic, oxytocin and prostaglandin F2α) and was dependent on the extracellular Ca2+. Contraction, however, was not dependent on the Ca2+ release from the internal stores. This in-vitro study provides the first scientific evidence on the claimed effect of Ficus Deltoidea on uterine contraction.