Standardized Terminalia chebula fruit extract – a sustainable approach to protect human skin from ultraviolet radiation, smartphone’ blue light and free radicals

The search for compounds to protect the skin from radiation and oxidative stress is focused on replacing chemosynthetic substances with sustainable natural alternatives. Synastol® TC, an extract from Terminalia chebula fruits standardized for high content of hydrolysable tannins, was evaluated for its protective ability against UV radiation, artificial blue light (BL) and free radicals. The extract demonstrated a Sun protection factor (SPF) of 26, which is 10-20 times higher than the SPF of three reference chemical UV filters at the same concentration. At a concentration of 1%, Synastol® TC was able to: (i) absorb UV radiation (290-400 nm) to values ​​exceeding the maximum measurable absorbance of the spectrophotometer used (3.999) and (ii) reduce the BL transmittance by up to 98.7% in the range of 415-455 nm associated with the induction of significant amounts of free radicals in the visible light region. After 1-hour exposure to two LED@450 nm with a total light intensity 35 times higher than that emitted by a typical smartphone screen and a wavelength corresponding to the peak of smartphone power spectrum, it can still reduce transmission of BL by 98.5%. Depending on the concentration, the ability of Synastol® TC to scavenge free radicals was 1.1-3 times higher, but the ferric reducing antioxidant power was several times weaker than that of synthetic α-tocopherol. Overall, in addition to its known health benefits, standardized T. chebula fruit extract may serve as a plant-based protectant against broad-spectrum UV radiation, digital blue light, and free radicals in skin care products.