From Himba indigenous knowledge to engineered Fe₂O₃ UV-blocking green nanocosmetics

Area of Science:

• Materials Science
• Nanotechnology
• Indigenous Knowledge Systems

Background:

• The Himba community in Namibia utilizes a traditional skin formulation called Otjize, derived from natural red ochre.
• Otjize is traditionally used for skin protection and cosmetic purposes.
• Understanding the scientific basis of Otjize's efficacy can provide insights into natural UV protection and antimicrobial agents.

Purpose of the Study:

• To investigate the physical properties of Namibian red ochre used in Otjize.
• To validate the composition and structure of the red ochre nanoparticles.
• To assess the UV filtration, IR reflectivity, and antimicrobial activity of the red ochre formulation.

Main Methods:

• Morphological and crystallographic studies were conducted to analyze the ochre's structure.
• Optical investigations were performed to evaluate UV filtration and IR reflectivity.
• Antibacterial assays were used to test efficacy against E. coli and S. aureus.

Main Results:

• The red ochre is predominantly composed of nano-scaled rhombohedral α-Fe2O3 nanocrystals with some γ-FeOOH.
• Exceptional UV filtration and significant IR reflectivity were observed.
• The ochre demonstrated non-negligible antibacterial activity against E. coli and S. aureus.

Conclusions:

• The study confirms the effectiveness of Otjize as a natural UV protection cream.
• The findings support the use of this indigenous formulation for its solar heat reflection properties.
• The antimicrobial efficacy of Otjize against common bacteria is scientifically substantiated.