Abstract:The object of this study was to discover an alternative therapeutic agent with fewer side effects against acne vulgaris, one of the most common skin diseases. Acne vulgaris is often associated with acne-related bacteria such as Propionibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus, and Pseudomonas aeruginosa. Some of these bacteria exhibit a resistance against commercial antibiotics that have been used in the treatment of acne vulgaris (tetracycline, erythromycin, and lincomycin). In the current study, we tested in vitro antibacterial effect of chitosan-phytochemical conjugates on acne-related bacteria. Three chitosan-phytochemical conjugates used in this study exhibited stronger antibacterial activity than that of chitosan (unmodified control). Chitosan-caffeic acid conjugate (CCA) showed the highest antibacterial effect on acne-related bacteria along with minimum inhibitory concentration (MIC; 8 to 256 µg/mL). Additionally, the MIC values of antibiotics against antibiotic-resistant P. acnes and P. aeruginosa strains were dramatically reduced in combination with CCA, suggesting that CCA would restore the antibacterial activity of the antibiotics. The analysis of fractional inhibitory concentration (FIC) indices clearly revealed a synergistic antibacterial effect of CCA with antibiotics. Thus, the median sum of FIC (∑FIC) values against the antibiotic-resistant bacterial strains ranged from 0.375 to 0.533 in the combination mode of CCA and antibiotics. The results of the present study suggested a potential possibility of chitosan-phytochemical conjugates in the control of infections related to acne vulgaris.

(LM) is an important food borne pathogen responsible for listeriosis. Further, LM is an etiological agent associated with life threatening conditions like meningitis and encephalitis. Biofilm forming and drug resistant LM may potentially become difficult to treat infections and hence effective controlling measures are required to prevent LM infections. In view of this, the present study evaluated an anti-listerial potential of edible brown seaweed, , by disc diffusion and micro-dilution methods. The results of the present study suggested that the anti-listerial activity of various phlorotannins isolated form were in the range of 16-256 µg/ml. Among the phlorotannins isolated, fucofuroeckol-A (FAA) exhibited the highest anti-listerial potential (MIC range 16-32 µg/ml) against LM strains tested. Further, in checker board synergy assays, FFA-streptomycin combination exhibited significant synergy (fractional inhibitory concentration index, ∑FIC < 0.5) against aminoglycoside resistant clinical strains of LM. The results of the present study suggested the potential use of edible seaweed as a source of natural phlorotannins to control food borne pathogenic infections.

To develop an antibacterial treatment for acne vulgaris using natural substance with few side effects, we investigated the antibacterial activities of oligochitosan against acne-related bacteria, particularly . Oligochitosan showed potent antibacterial effect on. Especially, 10 kDa oligochitosan presented the highest antimicrobial effect with minimum inhibitory concentration values of 32-64 μg/mL on . In addition, oligochitosan clearly reversed the antibacterial effect of tetracycline and erythromycin on in the combination mode. The combination of tetracycline- or erythromycine-10 kDa oligochitosan resulted in a median ΣFIC range of 0.02-0.56, suggesting that the antibiotics-oligochitosan combination resulted in an antibacterial synergy against . Thus, the results obtained in this research strongly supported that erythromycin and tetracycline will restore the antibacterial activity against in the combination mode with 10 kDa oligochitosan.

Abstract:The object of this study was to discover an alternative therapeutic agent with fewer side effects against acne vulgaris, which is one of the most common skin diseases. Acne vulgaris often associates with acne-related bacteria such as Propionibacterium acnes, Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa, some of which exhibit a resistant against commercial antibiotics used in the treatment of acne vulgaris (tetracycline, erythromycin, and lincomycin). In the current study, we evaluated in vitro antibacterial activity of chitosanphytochemical conjugates against acne-related bacteria. Three of chitosan-phytochemical conjugates used in this study showed stronger antibacterial activity than that of chitosan (unmodified control). Chitosan-caffeic acid conjugate (CCA) exhibited the highest antibacterial activity against acne-related bacteria with minimum inhibitory concentration values of 8 μg/mL to 256 μg/mL. In addition, the MICs of antibiotics against antibiotic resistant P. acnes and P. aeruginosa strains were dramatically reduced in the combination with CCA, suggesting that CCA would restore the antibacterial activity of the antibiotics. The analysis of fractional inhibitory concentration indices clearly revealed a synergistic antibacterial effect between CCA and the antibiotics. Thus, the median ∑FIC values against the antibiotic resistant bacterial strains were ranged from 0.375 to 0.533 in the combination mode of CCA and antibiotics.