title: Effects of chitosan on Candida albicans: conditions for its antifungal activity.
abstract: The effects of low molecular weight (96.5 KDa) chitosan on the pathogenic yeast Candida albicans were studied. Low concentrations of chitosan, around 2.5 to 10 μ g·mL(-1) produced (a) an efflux of K(+) and stimulation of extracellular acidification, (b) an inhibition of Rb(+) uptake, (c) an increased transmembrane potential difference of the cells, and (d) an increased uptake of Ca(2+). It is proposed that these effects are due to a decrease of the negative surface charge of the cells resulting from a strong binding of the polymer to the cells. At higher concentrations, besides the efflux of K(+), it produced (a) a large efflux of phosphates and material absorbing at 260 nm, (b) a decreased uptake of Ca(2+), (c) an inhibition of fermentation and respiration, and (d) the inhibition of growth. The effects depend on the medium used and the amount of cells, but in YPD high concentrations close to 1 mg·mL(-1) are required to produce the disruption of the cell membrane, the efflux of protein, and the growth inhibition. Besides the findings at low chitosan concentrations, this work provides an insight of the conditions required for chitosan to act as a fungistatic or antifungal and proposes a method for the permeabilization of yeast cells.
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, DF, Mexico. apd@ifc.unam.mx
authors.forename: Antonio
authors.initials: A
authors.lastname: Peña
authors.forename: Norma Silvia
authors.initials: NS
authors.lastname: Sánchez
authors.forename: Martha
authors.initials: M
authors.lastname: Calahorra
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002176:Candida albicans / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D002463:Cell Membrane Permeability / Q000187:drug effects; D002688:Chitinases / Q000378:metabolism; D048271:Chitosan / Q000494:pharmacology*; D015169:Colony Count, Microbial; D057075:Enzyme Assays; D005285:Fermentation / Q000187:drug effects; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D009711:Nucleotides / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010710:Phosphates / Q000378:metabolism; D011188:Potassium / Q000378:metabolism / Q000494:pharmacology; D012413:Rubidium / Q000378:metabolism; D055672:Static Electricity
chemical_list: D000935:Antifungal Agents; D009711:Nucleotides; D010710:Phosphates; D048271:Chitosan; D005954:Glucosephosphate Dehydrogenase; D002688:Chitinases; D012413:Rubidium; D011188:Potassium; D002118:Calcium