Antileukoprotease (ALP), or secretory leukocyte proteinase inhibitor, is an endogenous inhibitor of serine proteinases that is present in various external secretions. ALP, one of the major inhibitors of serine proteinases present in the human lung, is a potent reversible inhibitor of elastase and, to a lesser extent, of cathepsin G. In equine neutrophils, an antimicrobial polypeptide that has some of the characteristics of ALP has been identified (M. A.

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Previous studies have suggested that endogenous protease inhibitors may participate in the mucosal host defense. Antileukoprotease (ALP) is an important protease inhibitor found on various mucosal surfaces, including those of the respiratory and genital tracts. This study reports on the antimicrobial activity of recombinant (r) ALP toward the human fungal pathogens Aspergillus fumigatus and Candida albicans. rALP expressed pronounced fungicidal activity toward metabolically active A. fumigatus conidia and C. albicans yeast cells; however, metabolically quiescent A. fumigatus conidia were totally resistant. In contrast with the protease inhibitory activity of rALP, the fungicidal activity was localized primarily in the NH2-terminal domain. On a molar base, the fungicidal activity of rALP was comparable with that of human defensins and lysozyme. In addition, rALP caused inhibition of C. albicans yeast cell growth. By exhibiting antifungal activity, ALP may play an important role in the innate mucosal defense against human pathogenic fungi.

Profound screening and evaluation methods for biocide-releasing polymer films are crucial for predicting applicability and therapeutic outcome of these drug delivery systems. For this purpose, we developed an agar overlay assay embedding biopolymer composite films in a seeded microbial lawn. By combining this approach with model-dependent analysis for agar diffusion, antimicrobial potency of the entrapped drug can be calculated in terms of minimum inhibitory concentrations (MICs). Thus, the topical antiseptic 4-hexylresorcinol (4-HR) was incorporated into poly(lactic-co-glycolic acid) (PLGA) films at different loadings up to 3.7 mg/cm2 surface area through a solvent casting technique. The antimicrobial activity of 4-HR released from these composite films was assessed against a panel of Gram-negative and Gram–positive bacteria, yeasts and filamentous fungi by the proposed assay. All the microbial strains tested were susceptible to PLGA-4-HR films with MIC values down to 0.4% (w/w). The presented approach serves as a reliable method in screening and quantifying the antimicrobial activity of polymer composite films. Moreover, 4-HR-loaded PLGA films are a promising biomaterial that may find future application in the biomedical and packaging sector.

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