Investigating the cosmeceutical potential of Spirostachys africana Sond. bark extracts used traditionally for child skincare by isiXhosa communities in South Africa.

Abstract

Traditional medicine derived from medicinal plants has been very critical in dealing health issues across many cultures, particularly in rural and underserved communities. In South Africa, the prevalence of skin disorders has necessitated the exploration of natural, culturally grounded remedies to complement modern dermatological practices. The study investigated the cosmeceutical potential of Spirostachys africana, an indigenous medicinal plant found in South Africa and is usually used by isiXhosa communities for curing skin conditions, particularly in children. To scientifically validate its ethnomedicinal applications, stem-bark extracts were evaluated for antibacterial activity against skin-relevant pathogens (Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus) using the microdilution method. Results revealed potent efficacy, with dichloromethane and ethanol extracts exhibiting minimal inhibitory concentrations (MICs) ranging from 0.19 to 1.56 µg/Ml. Petroleum ether extract showed modest inhibitory action with a MIC of 0.78 µg/mL. The aqueous extract displayed the highest MIC value of 3.12 µg/mL, indicating the least inhibitory activity against E. coli among the tested extracts. In vitro assays, including DPPH radical scavenging and β-carotene-linoleic acid model system (CLAMS), revealed significant free radical scavenging and lipid peroxidation inhibition capabilities. The DPPH assay showed a half maximal effective concentration (EC50) value of 83.26 ± 1.22 μg/mL and a maximum inhibition of 72.60 ± 0.24% at the highest tested concentrations. Additionally, anti-inflammatory assays demonstrated that ethanol and distilled water extracts exhibited strong 15-lipoxygenase inhibition (IC₅₀ values of 0.421 ± 0.079 µg/mL and 0.447 ± 0.057 µg/mL, respectively), while ethanol and petroleum ether extractsshowed moderate nitric oxide inhibition, further supporting the plant's potential therapeutic value. A rat model study demonstrated that the water extract demonstrated the least overall irritation potential, with a maximum visual score of 0.62 ± 0.05 at 72 h, indicating its suitability for topical applications. Ethanol and methanol extracts showed moderate concentration-dependent tyrosinase inhibition, reaching approximately 40-45% enzyme activity reduction at 2.5 × 10-6 mol/L, suggesting potential for skin-lightening applications. This study also evaluated the anti-tyrosinase activity of Spirostachys africana stem-bark extracts and found moderate enzyme inhibition compared to the potent effect of kojic acid. These findings suggested the potential of S. africana as a natural source of tyrosinase inhibitors for managing hyperpigmentation disorders, warranting further phytochemical investigation and compound isolation. These conclusions scientifically support the traditional application of S. africana in treating skin conditions and demonstrate its potential in addressing various dermatological concerns. The study emphasized the importance of integrating indigenous knowledge with modern scientific approaches in healthcare, particularly in resource-limited settings. Further research is recommended to extract and identify specific bioactive compounds, conduct in vivo and clinical studies, develop formulations, and ensure sustainable sourcing of this valuable medicinal plant resource. This comprehensive evaluation of S. africana contributes to the preservation of cultural heritage, biodiversity conservation, and the development of effective, accessible, and culturally appropriate therapeutic solutions for skin disorders.