Woodvine Otieno1, Chengcheng Liu1, Hong Deng2, Jiao Li1, Xiaoyan Zeng3, Yanhong Ji1. 1. Department of Pathogenic Microbiology and Immunology, School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, P.R. China. 2. Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, P.R. China. 3. The First Affiliated Hospital of College of Medicine, Xi'an Jiaotong University, Xi'an, P.R. China.
Abstract
Background: The search for alternative therapeutics against antibiotic-resistant bacteria is highly desirable. A promising approach is photodynamic antimicrobial chemotherapy. Objective: This work evaluated the photodynamic inactivation (PDI) efficacy of hypocrellin B (HB) on Gram-positive antibiotic-resistant bacteria. Methods: PDI efficacy of HB on Gram-positive standard and antibiotic-resistant Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pneumonia and Gram-negative Escherichia coli and Klebsiella pneumoniae was assessed. HB photoactivity on biofilms formed by the Gram-positive bacteria and its cytotoxicity on mammalian CT26 cells were also investigated. Results: HB showed no obvious dark toxicity, but provided concentration-dependent inactivation of bacteria and mammalian cells. After irradiation with 72 J/cm2 light, 100 μM of HB achieved about 7 log10 reductions in bacterial survival of Gram-positive strains, but yielded only 2 log10 reductions in bacterial survival of Gram-negative strains. Gram-positive bacteria were as susceptible to PDI in biofilms as in planktonic suspensions, but the efficacy was attenuated. Conclusions: The results suggested that HB could serve as a potential antibacterial photosensitizer against Gram-positive antibiotic-resistant bacteria.
Background: The search for alternative therapeutics against antibiotic-resistant bacteria is highly desirable. A promising approach is photodynamic antimicrobial chemotherapy. Objective: This work evaluated the photodynamic inactivation (PDI) efficacy of hypocrellin B (HB) on Gram-positive antibiotic-resistant bacteria. Methods: PDI efficacy of HB on Gram-positive standard and antibiotic-resistant Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pneumonia and Gram-negative Escherichia coli and Klebsiella pneumoniae was assessed. HB photoactivity on biofilms formed by the Gram-positive bacteria and its cytotoxicity on mammalianCT26 cells were also investigated. Results:HB showed no obvious dark toxicity, but provided concentration-dependent inactivation of bacteria and mammalian cells. After irradiation with 72 J/cm2 light, 100 μM of HB achieved about 7 log10 reductions in bacterial survival of Gram-positive strains, but yielded only 2 log10 reductions in bacterial survival of Gram-negative strains. Gram-positive bacteria were as susceptible to PDI in biofilms as in planktonic suspensions, but the efficacy was attenuated. Conclusions: The results suggested that HB could serve as a potential antibacterial photosensitizer against Gram-positive antibiotic-resistant bacteria.