title: Glycerol Monolaurate Inhibits Lipase Production by Clinical Ocular Isolates Without Affecting Bacterial Cell Viability.
abstract: OBJECTIVE
  We sought to determine the relative lipase production of a range of ocular bacterial isolates and to assess the efficacy of glycerol monolaurate (GML) in inhibiting this lipase production in high lipase-producing bacteria without affecting bacterial cell growth.
  
  
  METHODS
  Staphylococcus aureus,Staphylococcus epidermidis,Propionibacterium acnes, and Corynebacterium spp. were inoculated at a density of 10(6)/mL in varying concentrations of GML up to 25 μg/mL for 24 hours at 37 °C with constant shaking. Bacterial suspensions were centrifuged, bacterial cell density was determined, and production of bacterial lipase was quantified using a commercial lipase assay kit.
  
  
  RESULTS
  Staphylococcus spp. produced high levels of lipase activity compared with P. acnes and Corynebacterium spp. GML inhibited lipase production by Staphylococcal spp. in a dose-dependent manner, with S. epidermidis lipase production consistently more sensitive to GML than S. aureus. Glycerol monolaurate showed significant (P < 0.05) lipase inhibition above concentrations of 15 μg/mL in S. aureus and was not cytotoxic up to 25 μg/mL. For S. epidermidis, GML showed significant (P < 0.05) lipase inhibition above 7.5 μg/mL.
  
  
  CONCLUSIONS
  Lipase activity varied between species and between strains. Staphylococcal spp. produced higher lipase activity compared with P. acnes and Corynebacterium spp. Glycerol monolaurate inhibited lipase production by S. aureus and S. epidermidis at concentrations that did not adversely affect bacterial cell growth. GML can be used to inhibit ocular bacterial lipase production without proving detrimental to commensal bacteria viability.
authors.affiliation: Brien Holden Vision Institute Sydney, Australia 2School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.
authors.forename: Judith Louise
authors.initials: JL
authors.lastname: Flanagan
authors.affiliation: Brien Holden Vision Institute Sydney, Australia.
authors.forename: Neeta
authors.initials: N
authors.lastname: Khandekar
authors.affiliation: Brien Holden Vision Institute Sydney, Australia 2School of Optometry and Vision Science, University of New South Wales, Sydney, Australia 3Vision Cooperative Research Centre, Sydney, Australia.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Kinki University School of Medicine, Osaka, Japan.
authors.forename: Keizo
authors.initials: K
authors.lastname: Watanabe
authors.affiliation: School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.
authors.forename: Maria
authors.initials: M
authors.lastname: Markoulli
authors.affiliation: Sydney Business School, University of Wollongong, Wollongong, Australia.
authors.forename: John Terence
authors.initials: JT
authors.lastname: Flanagan
authors.affiliation: Brien Holden Vision Institute Sydney, Australia 2School of Optometry and Vision Science, University of New South Wales, Sydney, Australia 3Vision Cooperative Research Centre, Sydney, Australia.
authors.forename: Eric
authors.initials: E
authors.lastname: Papas
mesh_terms: D002470:Cell Survival; D003124:Colorimetry; D015818:Eye Infections, Bacterial / Q000382:microbiology*; D006801:Humans; D007848:Laurates / Q000494:pharmacology*; D008049:Lipase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis; D008826:Microbial Sensitivity Tests; D050178:Monoglycerides / Q000494:pharmacology*; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D013501:Surface-Active Agents
chemical_list: D007848:Laurates; D050178:Monoglycerides; D013501:Surface-Active Agents; C020777:monolaurin; D008049:Lipase