The effect of a South African Helichrysum sp. against important pathogenic mechanisms of Propionibacterium acnes

Acne vulgaris is a chronic inflammatory skin disorder affecting the pilosebaceous follicles. It is characterized by lesions which include comedones, papules and pustules. In more severe cases nodules or cysts may be observed [1]. Lesions are often found in areas rich with sebaceous glands. Although acne has a low mortality rate, permanent disfigurement and scarring often result in psychosocial issues such as depression [2]. The aim of this study was to investigate the potential of a Helichrysum sp. as a natural ingredient in anti-acne agents. The Minimum Inhibitory Concentration (MIC) of the extract was determined using the micro-dilution broth method. The cell proliferation kit II was used to determine the effect on cell viability. Anti-inflammatory potential against COX (cyclooxygenase) II was determined using an ELISA kit. Column chromatographic separation was performed using SiO2 (Silica gel). The Helichrysum sp. extract exhibited an MIC of 7.81 µg/ml. Three major fractions were identified Fg, Fh and Fn. The MIC for each fraction was observed at 7.81 µg/ml, 7.81 µg/ml and 62.50 µg/ml, respectively. The extract and the major fraction MICs were compared with known antibiotic tetracycline, with an MIC of 1.56 µg/ml. Fraction Fg was further separated using a basic alumina column. The cytotoxicity of the extract was tested using human keratinocytes (HaCaT) and exhibited a fifty percent inhibitory concentration (IC₅₀) of 201.30 ± 23.45 µg/ml. The Selectivity Index (SI) was calculated as 25.77 (IC₅₀/MIC). The SI of the extract shows a worthy therapeutic window (> 10) indicating the potential for inhibition of inflammatory cytokines such as IL-8 and TNF-α [3]. The extract inhibited human COX II activity with an IC₅₀ of 21.97 ± 4.27 µg/ml. The potential of this Helichrysum sp. as a natural ingredient for acne has been shown. More research needs to be conducted to strengthen the cosmetic application showing the need for clinical trial research for efficacy and safety.

Acknowledgements: University of Pretoria and the National Research Foundation (NRF).

Keywords: Acne vulgaris, Helichrysum sp., anti-inflammatory, cytotoxicity.

References:

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