In the frame of MICROSMETICS EU project 57 potential candidate actinobacteria strains of global biodiversity were selected to be studied. In total 614 extracts were produced and a broad spectrum of cell-free bioassays have being incorporated for the evaluation of their anti-ageing activity, including analyses for anti-oxidant, skin-protecting and skin-whitening bioactivity [1].
Among the initial 614 extracts, 12 actinobacteria strains were selected as promising bioactive products and have been further evaluated in cell-based assays for their bleaching activity (i.e. tyrosinase inhibition) in mouse melanocytes (B16F10 cell line), as well as in normal human skin fibroblasts for their capacity to activate proteostasis ensuring anti-ageing mechanisms, namely the ubiquitin-proteasome and autophagy-lysosomal systems. The most bioactive strains CA-129531, CA-126581 and CA-218259 have been selected for dereplication, cultivation in larger scale and bioguided fractionation and identification of bioactive compounds.
The dereplication was performed using UPLC-HRMS while the isolation of the compounds contained in those extracts was performed using chromatographic methods like HPLC and FCPC. The full set of spectroscopic data (HRMS and NMR) was recorded for all isolated compounds in order to unambiguously elucidate their structure.
The evaluation of the isolated compounds in cell-free and mammalian cell based assays emphasized the anti-ageing effect of several metabolites produced by the selected strains. Special attention was given to isolated hydroxamic acid and histidine derivatives due to their remarkable skin-whitening activity and capacity to activate proteostasis as well as to deferoxamine and conjugates for their strong capacity to chelate iron, a free radical catalyst, known to be accumulated with age. Therefore, these extracts can be considered as potential candidates for industrial development and can serve as a proof of concept that microbial ingredients can have successful applications in cosmeceutical industry.
References:[1] K. Georgousaki et al. High throughput screening of microbial biodiversity for the discovery of novel cosmeceutical agents. Planta Medica 2015; 81 - PM_234.