Making sunscreen with cashew oil?

An international research team headed by Prof. Dr. med. Till Opatz from the Institute of Organic Chemistry at Johannes Gutenberg University Mainz (JGU) and Prof. Dr. Med. Charles de Koning from the University of the Witwatersrand in Johannesburg have now succeeded in using cashew nut shell liquid (CNSL, alternatively known as cashew nut oil or cashew shell oil) instead of petroleum in organic synthesis. This liquid is produced in large quantities during the production process of the nuts and cannot be used as a food or animal feed. As a result, there is no competition between its use as a chemical raw material and production of foodstuffs.

Product of little commercial value but high technological potential

“With current concerns over the use of fossil resources for chemical synthesis of functional molecules and the effect that current UV absorbers in sunscreens have on the ecosystem, we define the xylochemical synthesis of different classes from aromatic UV absorbers utilizing cashew nut shell liquid – as a non‐edible bio‐renewable carbon source,” the researchers emphasize in their study, which was published in the European Journal of Organic Chemistry.

CNSL is a product of “little commercial value but with high technological potential,” Opatz and his team explain. Because the liquid contains readily extractable phenolic components as well as biological substances, which include, among others, antimicrobial, anti-inflammatory, antioxidant, insecticidal and even antitumoral substances. The phenols that are also contained in the cashew shell would be suitable as raw materials for chemical syntheses too.

According to the scientists, further research has yet to confirm whether the precisely-defined chemical UV absorbers obtained in this way are also suitable for sunscreens, how they are tolerated by the skin, and what effects they have on various organisms. “This research, however, is beyond the scope of the current project funded by the German Federal Ministry of Education and Research (BMBF) and the South African NRF partner organization. Further research will require collaboration with industry.”