The antibacterial activity of topical retinoids: the case of retinaldehyde

摘要: Background: Retinoids such as retinoic acid (RA), retinol (ROL) and retinaldehyde (RAL) are currently used in many formulations indications ranging form acne to skin aging. Most if not all their pharmacological activities occur through binding nuclear receptors with subsequent modulation of the several genes. Little attention has been given other potential actions on surface skin. Aim: To analyse anti-infective topical ROL, RAL RA. Methods: Microbial minimal inhibitory concentrations (MIC) RA were determined by a microdilution method reference strains including Staphylococcus aureus, epidermidis, Micrococcus flavus, Propionibacterium acnes, luteus, Enterococcus faecium,Staphylococcus hominis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans 133 clinical methicillin-resistant S. methicillin-sensitive coagulase-negative Staphylococcus, Streptococcus group B, faecalis, vancomycin-resitant E. vancomycin-resistant faecium Pseudomonas/Klebsiella. In two trials healthy human volunteers, bacterial densities evaluated samples obtained cylinder scrub method: (1) 2 5 h after single application 0.05% or vehicle forearm (2) single-blind randomized study where applied daily for weeks forehead 22 volunteers. Paired results from treated (or vehicle) untreated areas analysed. Results: Of three retinoids tested, only showed significant vitro antibacterial activity; this activity was found against gram-positive bacteria like aeureus, spp. P. acnes. No gram-negative bacteria. These confirmed isolates. MIC50 MIC90 values 8 16 mg/l, respectively, aureus 4 mg/l aureus. The vivo studies that had decrease counts. study, median 102 log/cm2 acnes 101.8 staphylococci. resistant use. Preliminary suggest effect is due, part, aldehyde lateral chain, since non-retinoid pseudo-analogues citral hexenal, similar activity. Conclusion: We have shown differs parent natural ROL demonstrating upon This likely due isoprenoic which illustrates bifunctional properties some retinoids.