Characterization of Proteins and Antimicrobial Activity of Honey Collected from Different Sources
A number of compounds have been implicated for the antimicrobial activity of honey. This study was carried out to determine of peptides contributed to antimicrobial activity against selected multiantibiotic resistant pathogens. Honey samples obtained from different sources (Malaysian, Libyan and New...
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| Summary: | A number of compounds have been implicated for the antimicrobial activity of honey. This study was carried out to determine of peptides contributed to antimicrobial activity against selected multiantibiotic resistant pathogens. Honey samples obtained from different sources (Malaysian, Libyan and New Zealand) were evaluated for the antimicrobial properties against Staphylococcus aureus, Salmonella Typhimurium, Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa using five methods. The antimicrobial activity of honey was detected at lower concentration (12%) and microtiter plate method was the best. Adjusting the Ph of honey to 3, 5 and 7 resulted in slight changes in antibacterial activity either increase or decrease depending on source of honey. The antibacterial activity of honey samples was not affected by heating at 80 and 100°C for 10 min, but a slight increase in activity was detected after heating at 121°C for 10 min. Treating honey samples with the enzymes chymotrypsin and pepsin decreased antibacterial activity of honey samples except for Tualang honey (H026) and Acacia honey (H031) which showed significant (p˂0.05) increase against all pathogens, indicating protein were involved in the antimicrobial activity. The protein content of honey samples varied from 0.315 to 1.426 mg/ml, H026 (Tualang honey, 1.426 mg/ml), H020 (Hannon honey, 1.289 mg/ml), H032 (Acacia honey, 1.203 mg/ml), H031 (Acacia hpney, 0.567 mg/ml), H035 (Manuka honey, 0.570mg/ml), and H030 (Acacia honey, 0.315 mg/ml). Total amoni acids content of honey was in the range of 1.290±0.027 to 2.670±0.580 g/100g and consists of variable amounts of essential amoni acids among the honey samples. Acacia honey contains eight of the essential amino acids especially threonine (0.044±0.013 g/100g) and, highest concentrations of the non-essential amino acids (aspartic acid and tyrosine). High concentration of serine, glycine, methionine and lysine were detected in Alseder honey compared to other honey samples. The peptide content as evaluated by OPA method showed that H026 (Tualang honey) was 1.542mg/ml followed by H032 (Acacia honey, 1.140mg/ml) and the lowest amount was shown by H035 (Manuka honey, 0.076mg/ml). Peptide was not detected in H020 (Hannon honey) and H027 (Manuka honey). Protein fractions of honey samples were further separated by RP-HPLC. The antimicrobial activity seems to be related to the peptide content; fraction 7 from H032 (Acacia honey) showed the highest peptide content (3.27 Mm) and high antibacterial activity (78.53%). While fractions 3 and 4 from H026 (Tualang honey) showed slightly lower peptide content (3.11 and 2.76 Mm, respectively), but higher antibacterial activity (96.02 and 78.67%). Fractions 7 to 13 obtained from Sephadex G-50 Fine column chromatography showed proteins with different molecular weights (6 to 250 kDa) as detected using SDS-PAGE. Fractions 9 from sample H026 (Tualang honey and fractions 11 from samples H032 (Acacia honey) showed high peptide content (0.937 and 0.450mg/ml) and moderate antibacterial activity (41.02 and 37.26%, respectively). Fourteen de nova peptides were detected from of Tualang honey nd five de novo peptides from Acacia honey. Therefore, this study showed that honey contains antibacterial peptides both from known sources and de novo that contribute to the antimicrobial activity of honey. |
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