Sunlight is valued for its health benefits especially for the synthesis of Vitamin D. Although its prolonged and unprotected exposure can have some irreversible health risks including skin cancers and other skin related problems . There are three major classes of UV light emitted by the sun viz. UVA (320–400 nm), UVB (290–320 nm), and UVC (200–290 nm). Since only UV A and UV B radiations can reach the earth surface and has affect on the skin ‘s epidermal layer they are considered for investigating potential UV filters .
The most commonly used active ingredients in sunscreens/ sunblocks are unsaturated, aromatic organic compounds that are capable of absorbing harmful UV photons at a great range of wavelengths. The degree of conjugation and molar absorptivity of these compounds determines their absorption capabilities .The mechanism of action of an organic filter involves absorption of energy by chromophores (unsaturated atoms or functional groups responsible for absorbing and reflecting light at a distinct angle). These chromophores go from a ground state to an excited state due to delocalization of the π-electrons in highly conjugated systems. The energy of UV light is then conveniently converted into infrared energy, or heat via absorption by electrons of the conjugated system .
Cinnamaldehyde derivatives are suitable for its use as UV filters due to its absorbance abilities within the UV ranges . Having this background on the mechanism and properties of organic filters, five potential organic filters were derived from two cinnamaldehyde derivatives by aldol condensation reactions . After the synthesis of these UV filters ,to verify their identities as dialdol products they were analyzed by nuclear magnetic resonance (NMR) and attenuated total reflection Fourier-transform infrared (FTIR) spectroscopies .Samples of the compounds were then analyzed using ultraviolet-visible (UV-vis) spectroscopy to determine their individual ranges and intensities of UV absorption .According to the absorbance ranges recorded , all five compounds cover the UVA range, compound 2 covers small amount of UVB range, and none of the compound covers the UVC range.
The next stage of this project may involve investigation of the protection and effectiveness of the UV blockers by conducting further studies on the degradation and photostability of each organic UV blocker to determine the shelf life of the compounds.
Reference :
Monica B. Pan, Chloe S. Hughes, Hailey N. Lynch, Marcia M. Schilling, Anuradha Liyana Pathiranage, "Investigation of Cinnamaldehyde Derivatives as Potential Organic UV Filters", Journal of Chemistry, vol. 2022, Article ID 7010428, 7 pages, 2022. https://doi.org/10.1155/2022/7010428
by Gauri Pillai
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