Ethnopharmacological study on plants used for skincare and beauty by some Xhosa communities.

Abstract

The paraphrase “beauty lies in the eyes of the beholder” by Plato, a Greek philosopher, has echoed through the fabrics of time and still echoes in our generation. The statement simply ought to refer to that the observer gets to decide what is “beautiful” in their eyes. The decision on what and who is beautiful is heavily influenced by one’s surroundings. In a digital-market environment the concept of beauty enhancement is paraded by bigger forces to drive their own agenda. The desire to enhance one’s facial appearance has significantly contributed to the observed growth of the beauty industry. The notable growth of the industry has in some cases resulted in unpleasant consequences due to the side effects of some of the products in the market. In this global-blooming industry products are traded and exchanged at a rapid rate. Introduction of safer natural beauty enhancement products are required for the South African market if we were to alleviate those with undesirable side effects and could combat some socio-economic challenges through job creation. The use of plants as the source of natural compounds has proven to be a reliable strategy in ethnopharmacological applications. The Eastern Cape Province has a rich plant biodiversity and the communities have immense indigenous knowledge (IK) on the use of these plants. There is a need to explore the pharmacological application of these plants by introducing beauty enhancement product formulations made from local resources. The project was aimed at documenting and conductingethnopharmacological evaluation of plants used for skincare and beauty for their potential in formulation of beauty enhancement products. An ethnobotanical survey was conducted to document plants that are used by communities in the Raymond Mhlaba municipality for skincare and beauty. Knowledge holders were identified by purpose sampling method and the interviews were conducted in isiXhosa using a structured questionnaire. Information on demographics, names of the plant, type of plant, plant part used, method of preparation and administration and frequency of use was collected and captured in the questionnaires. The Asphodelaceae and Asteraceae were the most represented families of the plants used for skincare and beauty. The communities used sustainable harvesting practices as the leaves were the most utilized plant parts. The most reported beauty enhancement uses were for achieving desired skin complexion and for skin smoothness, with both accounting up to 50% of the reported plant usages. Sixteen plants with the highest frequency index (FI) were selected from the ethnobotanical survey for ethnopharmacological studies related to beauty enhancement. This included Acokanthera oblongifolia (Hochst.) Codd, Aloe ferox Mill, Arctotis arctotoides (L.f) O.Hoffm, Bulbine frutescens (L.) Willd, Cassipourea flanaganii (Schinz) Alston, Chenopodium album L, Clausena anisata (Willd.) Hook.f ex Benth, Haemanthus albiflos Jacq, Marrubium vulgare L, Ilex mitis (L.) Radlk, Plantago lanceolata L, Rorippa nasturtium-aquaticum (L.) Hayek, Sonchus asper L, Symphytum officinale L, Ruta graveolens L and Urtica urens L. The antimicrobial activity of plant extracts was assessed using the microdilution bioassay to determine the minimum inhibitory concentrations (MIC). The antimicrobial activity of petroleum ether (PE), dichloromethane (DCM), 70% aqueous ethanol (v/v) and water extracts of the selected plants were assessed against infectious skin microorganisms including Bacillus subtilis ATCC 6051, Brevibacillus agric ATCC 51663, Staphylococcus aureus ATCC 12600, Staphylococcus epidermidis ATCC 12228, Escherichia coli ATCC 11775, Klebsiella pneumoniae ATCC 13883, Candida albicans ATCC 10231 and the dermatophytes Microsporum canis ATCC 36299, Trichophyton mentagrophytes ATCC 9533 and Trichophyton tonsurans ATCC 28942. The majority of the tested plant extracts were effective and inhibited the skin commensal bacteria E. coli with MIC values less than 100 μg/mL. Prolonged infections by commensal bacteria can condition the skin environment and provide favourable conditions for more opportunistic bacteria such as the Staphylococci genus. Ethanol extracts of C. flanaganii and U. urens expressed high antibacterial activity against S. aureus with MIC values less than 100 μg/mL. Ethanol extracts of R. graveolens and dichloromethane extracts of A. arctotoides were effective at inhibiting S. epidermidis and S. aureus, respectively. Inhibition of two opportunistic bacteria has a positive effect on skin tone, due to the scarring and darkening associated with infection by the Staphylococci genus. There was notable activity recorded against C. albicans and dermatophytes M. canis, T. mentagrophytes and T. tonsurans by extracts of A. oblongifolia, A. arctotoides, C. flanaganii, I. mitis and R. graveolens at different polarities with MIC’s less than 1000 μg/mL. The phenolic content and antioxidant activity of the plants were determined by assessing 50% aqueous methanol extracts (v/v) for their total phenolic and flavonoid content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP) and the coupled oxidation of linoleic acid and bleaching of β-carotene. The antioxidant mechanism of phenolic compounds associated with beauty enhancement has been proposed to be due to their free radical chain breaking capabilities, metal chelation, oxidant quenching and inhibition of enzymatic activity. The total phenolic content of A. ferox, I. mitis and C. flanaganii were significantly high with recorded values ranging from 37.87 to 50.34 mgGAE/g. The flavonoid content of C. flanaganii, A. oblongifolia and P. lanceolata were significantly high. Methanol extracts of R. graveolens and C. flanaganii expressed the highest antioxidant activity, with IC50 values comparable to the standard antioxidant when assessed for their DPPH radical scavenging activity. The presence of antioxidants in the skin structural layers has a positive effect on the health and function of the skin. Extracts of U. urens, A. ferox, C. flanaganii, B. frutescens, P. lanceolata, H. albiflos, M. vulgare, C. anisata, S. officinale and R. nasturtium-aquaticum expressed good metal chelating potential. The highest oxidative protection in the β-carotene linoleic acid model with comparative oxidation rate ratio (ORR) to the positive control was observed for C. flanaganii, S. officinale and U. urens. The results indicate the ability of the plant extracts to provide protection against increased levels of lipid peroxidation in the skin, an important factor in beauty enhancement, due to delaying the age process. The photo-protective effect of the plant extracts was measured by calculating the sun protection factor (SPF). The SPF is the ratio of ultraviolet (UV) radiation required to produce minimal erythema dose (MED) in protected skin to unprotected skin with higher values indicative of increased protection from photo damage. Ethanol extracts of P. lanceolata, C. flanaganii, A. oblongifolia, I. mitis and A. arctotoides exhibited SPF values of more than 15, which translated to photo protection of the skin against UVB radiation by more than 93.3%. The plant extracts demonstrated the highest absorbance of UVB radiation at a wavelength region between 300 – 305 nm. These will protect the skin against UV-induced oxidative damage and enhance the skin’s health and function. The inhibition of enzymes with beauty enhancement potential by the plant extracts was assessed against tyrosinase, secretory phospholipase A2 (sPLA2), lipoxygenase (15-LOX) and cyclooxygenase (COX-1 and COX-2). Ethanol extracts of R. nasturtium-aquaticum, C. anisata, S. officinale and C. flanaganii expressed good anti-tyrosinase activity. The coupled protection against UV-induced damage and modulation of the tyrosinase enzyme activity can be exploited to achieve the desired skin complexion. The anti-inflammatory studies revealed the potential of extracts of C. flanaganii, P. lanceolata and R. nasturtium-aquaticum to serve as dual inhibitors of 15-LOX and COX-2 enzymes. The inhibition of 15-LOX and COX-2 is effective at resolving psoriasis, a skin-inflammatory associated disease which has a negative effect on the health and beauty of the skin. The effectiveness of ethanol extracts of C. flanaganii, C. album, C. anisata and R. nasturtium-aquaticum in maintaining the cells health and function was examined on human epidermal melanocytes (HEM) cell lines. Ethanol extracts of C. flanaganii, C. album, C. anisata and R. nasturtium-aquaticum were able to inhibit cellular tyrosinase activity and therefore reduce melanin production. The effective concentrations of the extracts were further reported as non-toxic to melanocytes. The observed anti-tyrosinase activity of the extracts against HEM cell lines contribute positively in achieving the desired skin complexion while providing photo protection against UV-induced damage. Therefore, plant extracts that are efficient and safe to use can be incorporated into formulations intended for beauty enhancement and further analysed under clinical trials. The study further suggests that the model undertaken be promoted to individuals and corporations interested in formulation of cosmeceuticals to ensure the safety and efficiency of their products.