Antimicrobial Activity of Smilax china L. Root Extracts against the Acne-Causing Bacterium, Cutibacterium acnes, and Its Active Compounds.

The root of Smilax china L. is used in traditional Korean medicine. We found that the Smilax china L. root extract has strong antimicrobial activity against two Cutibacterium acnes strains (KCTC 3314 and KCTC 3320). The aim of this study was to identify the beneficial properties of Smilax china L. extracts for their potential use as active ingredients in cosmetics for the treatment of human skin acne. The high-performance liquid chromatography (HPLC) and liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC/QTOF/MS) methods were used to obtain the profile of secondary metabolites from the ethyl acetate-soluble fraction of the crude extract. Agar diffusion and resazurin-based broth microdilution assays were used to evaluate antimicrobial activity and minimum inhibitory concentrations (MIC), respectively. Among the 24 metabolites, quercetin, resveratrol, and oxyresveratrol were the most potent compounds against Cutibacterium acnes. Minimum inhibitory concentrations of quercetin, resveratrol, and oxyresveratrol were 31.25, 125, and 250 µg/mL, respectively.

Expression of a recombinant endolysin from bacteriophage CAP 10-3 with lytic activity against Cutibacterium acnes.

The bacteriophage CAP 10-3 forming plaques against Cutibacterium acnes which causes skin acne was previously isolated from human skin acne lesion. Incomplete whole genome sequence (WGS) of the bacteriophage CAP 10-3 was obtained and it had 29,643 bp long nucleotide with 53.86% GC content. The sequence was similar to C. acnes phage PAP 1-1 with a nucleotide sequence identity of 89.63% and the bacteriophage belonged to Pahexavirus. Bioinformatic analysis of the WGS predicted 147 ORFs and functions of 40 CDSs were identified. The predicted endolysin gene of bacteriophage CAP 10-3 was 858 bp long which was deduced as 285 amino acids (~ 31 kDa). The protein had the highest similarity with amino acid sequence of the endolysin from Propionibacterium phage PHL071N05 with 97.20% identity. The CAP 10-3 endolysin gene was amplified by PCR with primer pairs based on the gene sequence, cloned into an expression vector pET-15b and transformed into Escherichia coli BL21(DE3) strain. The predicted protein band (~ 33 kDa) for the recombinant endolysin was detected in an SDS-PAGE gel and western blot assay. The concentrated supernatant of cell lysate from E. coli BL21(DE3) (pET-15b_CAP10-3 end) and a partially purified recombinant CAP 10-3 endolysin showed antibacterial activity against C. acnes KCTC 3314 in a dose-dependent manner. In conclusion, the recombinant CAP 10-3 endolysin was successfully produced in E. coli strain and it can be considered as a therapeutic agent candidate for treatment of human skin acne.