Antioxidant and antimicrobial activities of selected medicinal plants from Algeria

Objective:To evaluate the antioxidant and antimicrobial activity of methanolic extract extracts of selected Algerian medicinal plants.Methods:Antioxidant activity of extracts was evaluated in terms of radical scavenging potential(2,2-diphenyl-1-picrylhydrazyl)and β-carotene bleaching assay.Total phenolic contents and flavonoid contents were also measured.Antimicrobial activity of these plants was examined against Bacillus subtilis,Staphylococcus aureus,Escherichia coli,Pseudomonas aeruginosa and Candida albicans.Results:The values of IC_(50) ranged from 4.30μg/mL to 486.6μg/mL for the DPPH method,while total antioxidant activity using β-carotene/linoleic acid bleaching assay ranged from 17.03%to 86.13%.It was found that Pistacia lentiscus showed the highest antioxidant capacities using DPPH assay(IC_(50)=4.30μg/mL),while Populus trimula,Origanum glandulosum,Centaurea calcitrapa,Sysimbrium officinalis and Rhamnus alaternus showed the highest percent of total antioxidant activity in β-carotene/linoleic acid bleaching assay.Total phenolic and flavonoid contents ranged from 3.96 to 259.65 mg GAE/g extract and from 1.13 to 26.84 mg QE/g extract,respectively.The most interesting antimicrobial activity was obtained from Sysimbrium officinalis,Rhamnus alaternus,Origanum glandulosum,Cupressus sempervirens,Pinus halipensis and Centaurea calcitrapa.Conclusions:The results indicated that the plants tested may be potential sources for isolation of natural antioxidant and antimicrobial compounds.

Comparative study of hypoglycemic and antibacterial activity of organic extracts of four Bangladeshi plants

Objective:To examine hypoglycemic and antibacterial activity against some Gram-positive and Gram-negative bacteria of organic extracts of four Bangladeshi plants.Methods:An in vivo hypoglycemic effect on mice model was used to check the hypoglycemic effect of four Bangladeshi herbal organic extracts viz.,roots of Curculigo recurvata W.T.Aiton(Satipata)(C.recurvata),leaf of Amorphophallus bulbifer Roxb.(Olkachu)(A.bulbifer),whole plant of Thunbergia grandiflora Roxb.(Nillata)(T.grandiflora)and leaf of Steudnera colocasiifolia K.Koch(Yunnan)(S.colocasiifolia)using glibenclamide as a positive control and water as a negative control.They were also tested for antibacterial activity on three Grampositive and four Gram-negative bacteria by disk diffusion method.C.recurvata,A.bulbifer and T.grandiflora were extracted with methanol and S.colocasiifolia was extracted with ethanol.Results:Among all the plant extract,only ethanol extract of S.colocasiifolia leaves at 800 mg/kg dose significantly(P<0.01)reduced fasting glucose level in normal mice as compared to standard drug glibenclamide(5 mg/kg).Ethanol extract of S.colocasiifolia leaves at 800 mg/kg dose decreased 20.28%of blood glucose level after 2 h of administration in normal mice,where glibenclamide decreased 39.63%.Methanol extract of T.grandiflora didn’t show any zone of inhibition against the tested bacteria,but other three extracts showed a wide range of zone of inhibition.However,none of the extract showed antibacterial activity against all the tested bacteria.Methanol extract of C.recurvata showed maximum zone of inhibition against Bacillus cereus[(10.50±0.50)mm],Salmonella typhi[(16.20±1.26)mm],Escherichia coli[(13.00±1.00)mm]and ethanol extract of S.colocasiifolia showed maximum zone of inhibition against Staphylococcus aureus[(11.20±1.26)mm],Bacillus subtilis[(12.00±0.50)mm],Salmonella paratyphi[(10.80±0.29)mm].Only methanol extract of A.bulbifer showed(8.50±0.50)mm and(7.20±0.76)mm zone of inhibition against Pseudomomas aeruginosa at 1000 and 800μg/disk dose respectively.Conclusions:Through our study,it was found that S.colocasiifolia could be considered as very promising and beneficial hypoglycemic agent.Although C.recurvata and S.colocasiifolia showed comparable high antibacterial activity,further studies should be needed to develop new antibacterial agent from them.S.colocasiifolia may be a potential source for the development of new oral hypoglycemic agent.

Evaluation of antibacterial activity of the brown Seaweed Turbinaria ornata(Turner)J.Agardh from Egypt

Objective:To investigate the potential antibacterial activities of ethanol extracts of Turbinaria ornata(T.ornata),Oleic acid(OA)and palmitic acid(PA)extracted from T.ornata as well as mixtures of OA and PA(1:1)against some bacterial species.Methods:Brown seaweed T.ornata was collected from Hurghada shores,Red Sea coast of Egypt.OA and PA were extracted from T.ornata.Ethanol extracts of T.ornata,OA,PA and mixtures of these two fatty acids(1:1)were tested for their antibacterial activities against Escherichia coli,Bacillus cereus,Bacillus subtilis,Klebsiella pneumonia and Staphylococcus aureus by the disc diffusion method.Results:Ethanol extracts of T.ornata,OA,PA and mixtures of OA and PA(1:1)showed antibacterial activities that increased significantly(least significant difference at 0.05 level)with increasing concentrations against all tested bacteria.Different concentrations of ethanol extracts of T.ornata and extracted OA showed its highest activity against Bacillus subtilis,while PA and mixtures of PA and OA(1:1)showed its highest activity against Bacillus cereus.The maximum inhibition activities were shown for mixtures of OA and PA(1:1).Scanning electron microscope showed that mixtures of OA and PA(1:1)caused plasmolysis and reduction in cell size of Escherichia coli.Conclusions:Different concentrations of T.ornata and its fatty acids showed activities against all tested bacteria.Therefore,it is a potential source of natural antimicrobial compounds.

Determination of the prevalence of extended spectrum β-lactamase in clinical samples collected from Dehradun City Hospital

Objective:To detect extended spectrumβ-lactamase(ESBL)and determine its prevalence in various clinical samples collected from Dehradun City Hospital.Methods:The samples were first cultured in MacConkey’s agar plates by streak plate method,then identified by Gram staining and biochemical tests.The isolated bacterial strains were then tested for antibiotic susceptibility by Kirby-Bauer method.The ESBL detection is then carried out by double disc diffusion method.Results:Off the 56 samples cultured,21 strains were identified which were six Escherichia coli(E.coli),six Klebsiella,four Proteus,four Pseudomonas aeruginosa(P.aeruginosa)and only one Acinetobacter.Eight out of 21(38.1%)strains including three of E.coli,three of Klebsiella and two of P.aeruginosa,were found to be resistance to all five antibiotics(piperacillin,amikacin,ampicillin,gentamicin,and ciprofloxacin).Initial screening using four antibiotics(cefotaxime,ceftazidime,aztreonam and ceftriaxone)and the final confirmatory test using ceftazidime/clavulanic acid and ceftazidime alone showed that 19.05%of all strains isolated were ESBL producers.Individually,16.67%E.coli,16.67%Klebsiella pneumoniae,25%P.aeruginosa and 100%Acinetobacter were found to be ESBL producers.Conclusions:Antibiotic resistance by ESBL has become a major risk factor worldwide,therefore routine checkup and accordingly prescription are suggested.