Control of Propionibacterium acnes by natural antimicrobial substances: Role of the bacteriocin AS-48 and lysozyme

We report the high susceptibility of several clinical isolates of Propionibacterium acnes from different sources (skin, bone, wound exudates, abscess or blood contamination) to the head-to-tail cyclized bacteriocin AS-48. This peptide is a feasible candidate for further pharmacological development against this bacterium, due to its physicochemical and biological characteristics, even when it is growing in a biofilm. Thus, the treatment of pre-formed biofilms with AS-48 resulted in a dose- and time-dependent disruption of the biofilm architecture beside the decrease of bacterial viability. Furthermore, we demonstrated the potential of lysozyme to bolster the inhibitory activity of AS-48 against P. acnes, rendering high reductions in the MIC values, even in matrix-growing cultures, according to the results obtained using a range of microscopy and bioassay techniques. The improvement of the activity of AS-48 through its co-formulation with lysozyme may be considered an alternative in the control of P. acnes, especially after proving the absence of cytotoxicity demonstrated by these natural compounds on relevant human skin cell lines. In summary, this study supports that compositions comprising the bacteriocin AS-48 plus lysozyme must be considered as promising candidates for topical applications with medical and pharmaceutical purposes against dermatological diseases such as acne vulgaris.This research was funded by a grant from the Spanish Ministry of Economy and Competitiveness (SAF2013-48971-C2-1-R that included funds from European Regional Development, ERDF), and the Research Group General (BIO160, UGR)

Mechanical properties of Aningeria superba (Aningre) and Austranella congolensis tannin adhesives

International audienc

Aningre (Aningeria spp.) tannin extract characterization and performance as an adhesive resin

International audienceAs aningre tree species are very abundant in central Africa, are rapid growing and have a very high percentage yield of tannin, aningre tannin extract was characterized using attenuated total reflectance Fourier transform (ATR-FT MIR) spectra in the 1800 and 600 cm(-1) range and Matrix Assisted Laser Desorption Ionisation Time of Flight (MALDI-TOF) mass spectrometry. These two characterization methods have proven that aningre tannin is a procyanindin/prodelphinidin composed of catechin, gallogatechin as well as galloylated catechin and gallocatechin units. Moreover, oligomers presenting the simultaneous combination of methoxy groups and linked glucose have been observed, these not having been observed before in bark and wood extracted tannins. Two resin formulations were developed with this extract. The Modulus of Elasticity (MOE) was studied by thermomechanical analysis and wood particleboards were prepared bonded with these resins