For millennia, clay and mushrooms have been used for their healing properties. Now, they are being blended for use in sunscreens.

In her PhD thesis at Ernst-Moritz-Arndt University of Greifswald, Germany, Dr Hoang-Minh Thao mixed clay minerals and ganoderma pfeifferi fungal extracts to improve the properties of UV-protection creams.

Non-natural filters used in UV-creams, such as titanium dioxide (TiO2), can cause problems to the skin. Thao explains, ‘Due to the nano- and micrometre-sized particles used in cosmetics, TiO2 does not reflect and scatter UV-radiation as an intensive “physical sunscreen.” It is photocatalytically active. The photocatalytic effect is harmful for skin health’.

Thao found that, clays block UV radiation and that some ganoderma species have a scavenging effect on free radicals. ‘They exhibit an anti-oxidative effect and cause a delay of the skin aging process. Therefore, we have tried to combine clay and extracts from ganoderma pfeifferi to substitute for non-natural additives in UV-protection cream.’

One millilitre of the fungal extract was added to one gramme of a wool-wax-alcohol ointment (mainly liquid vaseline) and then blended with 0.1g of clay. The ointment base was used to compare the mixture of the extract with different clays.

She explains that combining clay and ganoderma extract creates a high protection suncream without the photocatalytic effect of non-natural additives, especially when the clay is dominated by an expandable clay mineral with low layer charge.

She underpins the importance of low layer charge, ‘The clay mineral with low layer charge yielded a homogeneous distribution of the clay mineral particles, and the ganoderma pfeifferi extract combined with the alkyl glucoside that entered the interlayer space caused the effective protection towards UV radiation.’

The resultant cream was tested at the 250- 400nm wavelength for radiation to incorporate the risks of skin aging and cancer. ‘We tested the mixtures against a commercially available suncream with an SPF of 20,’ she notes. ‘Our results show that the mixture of the ganoderma pfeifferi extract with the Friedland clay (from Germany) provided a better UV radiation protection than the trade ware, especially in the wavelength range of 280-295nm.’

According to Thao, the UV-protection capacity of the studied clays with the extract ranged from 77-97%. She adds that the market price of TiO2 is between US$3,300-3,500 per tonne, while the price of raw clay is less than US$250p/t. However, she notes that the grey colour of the mixtures may not be favourable for cosmetic products.

At present, Thao and her colleagues in Greifswald are liaising with SMEs to apply the innovation in products, and are looking for a suitable Vietnamese clay for application.