Exploitation of Streptomyces lopnurensis isolated from the marine environment of Golf of Thailand for the discovery of novel skin whitening agents

In continuation of our research on investigating the marine environment, more than 300 microorganisms were isolated from invertebrates of the Indian Ocean, the Red Sea and the Mediterranean. The microorganisms were cultivated and extracted by optimized protocols in and a library of more than 1200 extracts was established. The initial screening revealed that 0.5% of the extracts showed inhibitory activity against tyrosinase and elastase. Subsequently, selected extracts were further evaluated for their ability to inhibit tyrosinase in normal diploid human dermal fibroblasts.

Among the most active extracts, the one from Streptomyces lopnurensis; an actinomycete isolated from a sea cucumber of genus Synaptula collected from Sattahip Beach (Gulf of Thailand), inhibited tyrosinase in both cell-free and cell-based assays (93.2% at 300 μg/mL and 30.2% at the concentration of 10 μg/mL, respectively).

The microorganism was re-cultivated in 10L scale, under solid and liquid conditions in Marine Broth, using in-situ solid phase extraction technology (XAD-16) and it was then extracted with AcOEt and MeOH. Biological activity was confirmed by cell-free tyrosinase enzymatic assay (inhibition activity ranged between 33.61-83.56% at 300μg/mL) and the most active extract was further fractionated. All fractions were purified by preparative techniques (HPLC, TLC), while NMR and LC-MS methodologies were implemented for the identification and structure elucidation of the isolated compounds. All compounds have been further investigated for their biological activity against tyrosinase in cell-free and cell-based assays.

• References

• 1 Vlachou. et al. Innovative Approach to Sustainable Marine Invertebrate Chemistry and a Scale-Up Technology for Open Marine Ecosystems. Mar Drugs 2018; 16 (05) 152. https://doi.org/10.3390/md16050152
• 2 Zheng. et al. Streptomyces lopnurensis sp. nov., an actinomycete isolated from soil. Int J Syst Evol Microbiol. 2014; 64 (Pt12): 4179–83. DOI: 10.1099/ijs.0.066357-0.