Publicação
Caracterização e avaliação das propriedades dos óleos essenciais Thymus caespititius e Thymbra capitata em preparações tópicas
| Resumo: | Today, consumers are looking for effective, safe and natural products that contribute to your health, wellness and beauty. As a result, the consumer created the need to develop new cosmetic products formulated with natural ingredients such as essential oils. These are complex mixtures of volatile, odoriferous and lipophilic secondary metabolites which are biosynthesized in specialized cells (secretory cells, epidermal cells, glandular trichomes), mainly present in aromatic plants. As natural ingredients, essential oils are a growing market trend for perfumery and cosmetic. In addition to the pleasant odor, they can also be important preservatives due to the strong antimicrobial activity. However, the essential oils are rather volatile and some of its constituents may cause skin sensitivity, for example, contact dermatitis and photoallergy. Thus, Annex III of Regulation No 1223/2009, provides a list of substances which cosmetic products must not contain out of the laid down restrictions. Preservatives are added to cosmetic products so that they have an extended shelf-life, preventing the development of microorganism that cause diseases to consumers or harm the appearance of the product. However, legislation concerning chemical preservatives has undergone changes and updates as a result of the knowledge of sensitivity and toxicity problems inherent to these products. This work aims at highlighting the potential of essential oils, with antimicrobial activity, isolated from native plants in Portugal: Thymus caespititius Brot., Thymbra capitata (L.) Cav., e Myrtus communis L., by including them in topical formulations, in order to assess their capacity as preservatives. The three essential oils, obtained from Th. caespititius, T. capitata and M. communis were isolated from the aerial parts of different flowering plants by hydrodistillation, analyzed by gas chromatography for components quantification and by gas chromatography-mass spectrometry, for components identification. All essential oils showed faint yellow colours. The isolated essential oils were complex mixtures, in which 64 constituents for Th. caespititius, 30 in T. capitata and 34 in M. communis were identified. Monoterpenes were the dominant class of compounds (76%, 97% and 91 %, respectively), whereas sesquiterpenes ranged between 2 and 16%, and phenylpropanoids from traces to 3%. α-Terpineol was the dominant compound Th. caespititius essential oil, while carvacrol dominated the T. capitata essential oil. 1,8-Cineole was the major compound present in the essential oil of M. communis. Based on chemical characterization of the three essential oils, including constituents considered as allergens (linalool, limonene, methyl eugenol, citronellol, geraniol and eugenol) present in Regulation 1223/2009, Annex III, two essential oils (Thymus caespititius and Thymbra capitata) out of three were chosen to be incorporated at 1% as bioactive ingredients in topical formulations and the three essential oils (Thymus caespititius, Thymbra capitata and Myrtus communis) were chosen to be incorporated at 0.5% in topical formulation, to be assessed for physical-chemical parameters: pH, viscosity, phase separation and particle size. As healthy skin pH is of approximately 5, and topical application to healthy skin products presenting pH of 4-6, the pH values for the emulsions of essential oil were within limits. Concerning viscosity, the addition of essential oils greatly increases the breakage resistance of the structure when compared to placebo. These results were in accordance with the analysis of particle size, since the incorporation of essential oils either 1 or 0.5% decreases the particle size. All emulsions were stable. Antimicrobial activity was evaluated by the method of Kirby-Bauer and by the method of microdilution plate determining the minimum inhibitory concentration and minimum bactericidal concentrations for the three essential oils with or without dilution in DMSO and, for two controls: Dermosoft® OMP and benzyl alcohol. Pseudomonas aeruginosa ATCC 9027 was extremely susceptible to the essential oil of T. capitata without dilution in DMSO; Staphylococcus aureus ATCC 6538 showed greater susceptibility to essential oils Th. caespititius and T. capitata and, lower susceptibility to M. communis essential oil diluted in DMSO (1: 100). The essential oils of Th. caespititius and T. capitata were effective against fungi, showing better antifungal activity than Dermosoft® OMP for Candida albicans ATCC 10231. Three essential oils (Th. caespititius, T. capitata e M. communis) showed better activity against Gram-positive than Gram-negative bacteria, and these results are in accordance with previous studies. All essential oils showed better results than the two controls. In summary, Th. caespititius, T. capitata and M. communis essential oils were effective against fungi, Gram-positive and Gram-negative bacteria. Regarding the challenge test, emulsions with 1% T. caespititius essential oil and T. capitata essential oil and emulsion with 0.5% M. communis essential oil are in accordance with the acceptance criteria A (2 Log10 reduction) for the fungi (Candida albicans ATCC 10231 and Aspergillus brasiliensis ATCC 16404) as well as the bacteria (ATCCC 9027 Pseudomonas aeruginosa and Staphylococcus aureus ATCC 6538). Th. caespititius and T. capitata essential oils showed potential as alternative preservatives for use in topical formulations. Although the essential oil emulsion with M. communis is in accordance with criteria acceptance of the challenge test (FP 9), the percentage of allergen: methyl eugenol exceeds in percentage used (0.5% essential oil) the maximum concentration permitted by law (Regulation nº 1223/2009, Annex III). |
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| Autores principais: | Neves, Ana Maria da Silva |
| Assunto: | Essential oil Activity-antimicrobial Preservatives Emulsions Teses de mestrado - 2016 |
| Ano: | 2016 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Today, consumers are looking for effective, safe and natural products that contribute to your health, wellness and beauty. As a result, the consumer created the need to develop new cosmetic products formulated with natural ingredients such as essential oils. These are complex mixtures of volatile, odoriferous and lipophilic secondary metabolites which are biosynthesized in specialized cells (secretory cells, epidermal cells, glandular trichomes), mainly present in aromatic plants. As natural ingredients, essential oils are a growing market trend for perfumery and cosmetic. In addition to the pleasant odor, they can also be important preservatives due to the strong antimicrobial activity. However, the essential oils are rather volatile and some of its constituents may cause skin sensitivity, for example, contact dermatitis and photoallergy. Thus, Annex III of Regulation No 1223/2009, provides a list of substances which cosmetic products must not contain out of the laid down restrictions. Preservatives are added to cosmetic products so that they have an extended shelf-life, preventing the development of microorganism that cause diseases to consumers or harm the appearance of the product. However, legislation concerning chemical preservatives has undergone changes and updates as a result of the knowledge of sensitivity and toxicity problems inherent to these products. This work aims at highlighting the potential of essential oils, with antimicrobial activity, isolated from native plants in Portugal: Thymus caespititius Brot., Thymbra capitata (L.) Cav., e Myrtus communis L., by including them in topical formulations, in order to assess their capacity as preservatives. The three essential oils, obtained from Th. caespititius, T. capitata and M. communis were isolated from the aerial parts of different flowering plants by hydrodistillation, analyzed by gas chromatography for components quantification and by gas chromatography-mass spectrometry, for components identification. All essential oils showed faint yellow colours. The isolated essential oils were complex mixtures, in which 64 constituents for Th. caespititius, 30 in T. capitata and 34 in M. communis were identified. Monoterpenes were the dominant class of compounds (76%, 97% and 91 %, respectively), whereas sesquiterpenes ranged between 2 and 16%, and phenylpropanoids from traces to 3%. α-Terpineol was the dominant compound Th. caespititius essential oil, while carvacrol dominated the T. capitata essential oil. 1,8-Cineole was the major compound present in the essential oil of M. communis. Based on chemical characterization of the three essential oils, including constituents considered as allergens (linalool, limonene, methyl eugenol, citronellol, geraniol and eugenol) present in Regulation 1223/2009, Annex III, two essential oils (Thymus caespititius and Thymbra capitata) out of three were chosen to be incorporated at 1% as bioactive ingredients in topical formulations and the three essential oils (Thymus caespititius, Thymbra capitata and Myrtus communis) were chosen to be incorporated at 0.5% in topical formulation, to be assessed for physical-chemical parameters: pH, viscosity, phase separation and particle size. As healthy skin pH is of approximately 5, and topical application to healthy skin products presenting pH of 4-6, the pH values for the emulsions of essential oil were within limits. Concerning viscosity, the addition of essential oils greatly increases the breakage resistance of the structure when compared to placebo. These results were in accordance with the analysis of particle size, since the incorporation of essential oils either 1 or 0.5% decreases the particle size. All emulsions were stable. Antimicrobial activity was evaluated by the method of Kirby-Bauer and by the method of microdilution plate determining the minimum inhibitory concentration and minimum bactericidal concentrations for the three essential oils with or without dilution in DMSO and, for two controls: Dermosoft® OMP and benzyl alcohol. Pseudomonas aeruginosa ATCC 9027 was extremely susceptible to the essential oil of T. capitata without dilution in DMSO; Staphylococcus aureus ATCC 6538 showed greater susceptibility to essential oils Th. caespititius and T. capitata and, lower susceptibility to M. communis essential oil diluted in DMSO (1: 100). The essential oils of Th. caespititius and T. capitata were effective against fungi, showing better antifungal activity than Dermosoft® OMP for Candida albicans ATCC 10231. Three essential oils (Th. caespititius, T. capitata e M. communis) showed better activity against Gram-positive than Gram-negative bacteria, and these results are in accordance with previous studies. All essential oils showed better results than the two controls. In summary, Th. caespititius, T. capitata and M. communis essential oils were effective against fungi, Gram-positive and Gram-negative bacteria. Regarding the challenge test, emulsions with 1% T. caespititius essential oil and T. capitata essential oil and emulsion with 0.5% M. communis essential oil are in accordance with the acceptance criteria A (2 Log10 reduction) for the fungi (Candida albicans ATCC 10231 and Aspergillus brasiliensis ATCC 16404) as well as the bacteria (ATCCC 9027 Pseudomonas aeruginosa and Staphylococcus aureus ATCC 6538). Th. caespititius and T. capitata essential oils showed potential as alternative preservatives for use in topical formulations. Although the essential oil emulsion with M. communis is in accordance with criteria acceptance of the challenge test (FP 9), the percentage of allergen: methyl eugenol exceeds in percentage used (0.5% essential oil) the maximum concentration permitted by law (Regulation nº 1223/2009, Annex III). |
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