Potentials of Actinomycetes from Reserved Environments as Antibacterial Agents Against Drug-Resistant Clinical Bacterial Strains.

BACKGROUND: Increased antibiotic resistant properties of pathogens has led to a pronounced search for new effective antibiotics from microbes in diverse ecological niches. This study focused on isolating actinomycetes from soil of reserved areas and profiling them for antibacterial potentials. METHODS: The isolates (IS-2, IS-4, IS-6, IS-10, IS-14) were assessed for antagonistic activity against ten multi-drug resistant bacterial strains (Gram positive and negative) by cross streak and well diffusion methods. RESULTS: During the primary screening, four of the isolates showed good antagonistic activity against the test strains. Notably, all the bacterial strains except Pseudomonas aeruginosa responded sensitively to at least one of the actinomycetes screened. The crude extracts of the secondary metabolites of the four actinomycetes (IS-2, IS-4, IS-6, IS-10) with considerably significant antagonistic activities inhibited the growth of all the bacterial strains efficiently. All the test bacterial strains were sensitive to at least one of the extracts at a concentration of 100µg/ml. The minimum inhibitory concentration of the extracts against the isolates ranged from 12.5 - 25µg/ml. The crude extracts of IS-4 and IS-6 identified as Streptomyces glauciniger NBRC 100913 and Streptomyces griseoplanus NRRL-ISP 5009 by I6s rRNA sequencing, showed higher antibacterial activities against the bacterial strains. Significantly, the ethyl acetate crude extract of the actinomycetes demonstrated better antibacterial activities than the standard antibiotics (ofloxacin, amoxicillin/clavulanate, cefuroxime and ceftriaxone). CONCLUSION: This study reports remarkable anti-MRSA activities as well as broad spectrum antibacterial potentials of extracts of Streptomyces spp. worthy of further exploration.

In vitro Angiotesin-1-converting enzyme, α-amylase and α-glucosidase inhibitory and antioxidant activities of Luffa cylindrical (L.) M. Roem seed protein hydrolysate.

In recent times, researchers have explored food derived peptides to circumvent the side effects of synthetic drugs. This study therefore examined the amino acid constituents, in vitro antioxidant activities, angiotensin-1-converting enzyme (ACE), α-glucosidase and α-amylase inhibition kinetics of protein hydrolysate obtained from the seed of Luffa cylindrica. The peptide yield by pepsin (16.93 ± 0.28%) and trypsin (13.20 ± 1.02%) were significantly lower than that of Alcalase (34.04 ± 1.96%). Alcalase hydrolysate however displayed the highest ferric reducing antioxidant capacity (FRAC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and H2O2 scavenging activities (0.63%, 85.88% and 41.69% respectively), while the highest superoxide scavenging activity was shown by peptic hydrolysate (57.89%). The ACE inhibition by the hydrolysates with IC50 of 0.32-0.93 mg/mL, increased as the concentration of the peptic hydrolysate increased with the highest ACE-inhibitory activity (74.99 ± 0.43%) at 1.2 mg/mL of peptic hydrolysate. Tryptic and Alcalase hydrloysates exhibited a strong α-amylase inhibition having 27.96 ± 0.06% and 36.36 ± 0.71% inhibitory capacity respectively with IC50 of 1.02-3.31 mg/mL. Alcalase hydrolysates demonstrated the strongest inhibition (65.81 ± 1.95%), followed by tryptic hydrolysates (54.53 ± 0.52%) in a concentration-dependent inhibition of α-glucosidase (IC50 , 0.48-0.80 mg/mL). Kinetic analysis showed that ACE-inhibition by different concentrations of Alcalase, pepsin and trypsin hydrolysates is uncompetitive, mixed-type and non-competitive respectively. α-Amylase was non-competitively inhibited while α-glucosidase was un-competitively inhibited by all the hydrolysates. The total amino acid concentration for Alcalase, trypsin and pepsin hydrolysates was 53.51g/100g, 75.40g/100g and 85.42g/100g of Luffa cylindrica seed protein hydrolysate respectively, with glutamate being the most concentrated essential amino acid in all the three hydrolysates. From these results, it can be deduced that Luffa cylindrica seed Alcalase and tryptic protein hydrolysates may play critical and indispensible role as bio-tools in diabetes and hypertension treatment.