Abstract
Introduction: Indigenous knowledge systems (IKS) have long played a vital role in the healing of various ailments, including skin-related issues, by harnessing natural resources such as plants, minerals, and clays, often passed down through generations within communities. In South Africa, particularly in rural areas of the Eastern Cape and KwaZulu-Natal (KZN), clays such as Umcako and Ibomvu are commonly used in face masks for skincare and sun protection. While the use of clay in skincare is well-documented within IKS, there is limited research on the antimicrobial activity, effectiveness, and safety of these clays in relation to modern cosmetic and health standards.
Aim: This study aimed to evaluate the physical, chemical, and antimicrobial properties of Umcako and Ibomvu clays against acne pathogens in KZN.
Method: A prospective experimental design was employed to assess the physical, chemical, and antimicrobial properties of Umcako and Ibomvu clays. Physical and chemical analyses were conducted, including pH measurements, SPF testing, SEM, and mineral composition assessments using FT-IR, XRD, ICP-MS, and XRF. Antimicrobial activity was tested against ATCC strains of common acne pathogens using standard microbiological methods, such as Kirby Bauer disk diffusion and Minimum Inhibitory Concentration (MIC) assays.
Results: The analysis showed that both clays were compatible with skin pH and exhibited beneficial physical properties. Umcako clay had a higher kaolinite concentration (92.5%) compared to Ibomvu clay (77.3%). While both clays provided essential micronutrients like iron, zinc, and manganese, Ibomvu clay also contained higher levels of toxic elements, such as lead (53 ppm) and nickel (126 ppm). Whereas Umcako clay contained toxic lead (18 ppm) and chromium (460 ppm). Antimicrobial tests showed no inhibition zones against acne pathogens, indicating limited antimicrobial activity. This lack of effectiveness could be associated to the lack of active antimicrobial ingredients, elevated kaolin content and the influence of heavy metals on microbial resistance.
Conclusion: The findings suggest that while Umcako and Ibomvu clays have beneficial properties for skincare, concerns about heavy metal contamination need careful consideration. This highlights the need for safety assessments and regulatory standards for the cosmetic use of these clays to protect public health.