Ultraviolet absorption capacity is the most important factor for gadusol to be an UV absorber.
The above table shows different types of UV with various wavelength and photon energy. Among them, UVA and UVB are the two most harmful types for human beings and most current sunscreen products are targeted to UVB (315~280 nm).
From the prediction result of Chem Office based on molecular structure, we found our Gadusol product is a good UVB absorber with UV absorption capacity from 320~260 nm (Fig.1).
Fig.1 Gadusol UV Absorption Spectrum
Compared with current functional component's spectrum in chemical sunscreens like Octyl dimethylamino-benzoate (Fig.2), Gadusol had a similar UV absorption capacity around 290 nm.
Fig.2 Octyl Dimethylamino-benzoate UV Absorption Spectrum
Safety problem is the priority of our product and we conducted a cytotoxicity evaluation experiment with the help of ShanghaiTech_China.
To find out the cytotoxicity effect of Gadusol on human cells, we chose Human Umbilical Vein Endothelial Cells (HUVEC) as the test cells and set a concentration gradient of Gadusol to find out the potential influences (Most functional UV absorber was added under 50 mg/mL, so we set this concentration as the highest one.). We used the HUVEC with Fluorescein Diacetate/Propidium iodide, treated them with Gadusol and counted them after treatment under fluorescence microscope (Fig.3).
Live/dead staining can be performed with Fluorescein Diacetate (FDA) and Propidium iodide (PI). FDA is taken by cells that convert the non-fluorescent FDA into the green metabolite fluorescein. PI is an kind of ethidium bromide that releases red fluorescence after embedding in double-stranded DNA. It can be used in dead cells detection because it cannot pass through the living cell membrane, but can stain the nucleus through the damaged cell membrane. FDA is a non-fluorescent, nonpolar dye that accumulates in protoplast membrane, it can be detected by fluorescence microscope. Once FDA enters the protoplasts, which produce fluorescent polarity due to lipase decomposition, vibrant, intact cells will produce yellow-green fluorescence, while nonviable proplasts cannot decompose FDA, and thus are fluorescence-free. It can be used to detect living cells based on that. Finally, we found that Gadusol was harmless to cells (Fig.4) which gave us a preliminary proof of our product safety.
Fig.3 Cells with PI
Fig.4 Death Rate under different Gadusol Concentrations