Publicação
Unravelling new ethnopharmacological roles of Plectranthus species: biological activity screening
| Resumo: | This dissertation focused on the biological activity screening of several Plectranthus spp. plants, aiming to unravell novel ethnopharmacological roles and further research, of several extracts (methanol, ethyl acetate, acetone and water) and isolated compounds. Previous evidences on interesting biological activities of Plectranthus spp. constituents, directed the study for antioxidant, anti-skin ageing, anti-inflammatory, and anti-mycobacterial activities. Antioxidant results revealed an increased activity of the methanol extracts (20-76%), due to the presence of polyphenols widely known as antioxidants. Moreover, P. grandidentatus (62.3 ± 0.43%) and P. ecklonii (55.5 ± 1.66%) registered a high scavenging activity in the ethyl acetate extract, in comparison with quercetin (89.0 ± 2.5%), most likely due to the presence of abietane diterpenes. Acetylcholinesterase (AChE) was studied in vitro to evaluate the enzymatic inhibition, due to recent discoveries on non-neuronal cholinergic system in the skin. This assay showed that the Plectranthus spp. organic extracts did not significantly inhibited AChE. Concerning the tyrosinase inhibition assay, it was observed a high inhibition for the P. ecklonii methanol (65.9 ± 3.42%), P. grandidentatus acetone (67.9 ± 3.55%), and P. saccatus acetone (56.5 ± 5.68%) organic extracts. On the other hand, the aqueous extract of P. porcatus was the only one that showed enzymatic inhibition (65.0 ± 8.67%). From the tested isolated compounds, abietane diterpenes, mainly present in the organic extracts of P. grandidentatus, P. madagascariensis, and P. ecklonii were highly active against tyrosinase, in more than 46% and up to 75%, especially compared to kojic acid (92.9 ± 7.28%). In the collagenase assay, all tested extracts and compounds showed a high enzymatic inhibition which was in the range of 28-76%. The higher inhibition results were obtained from P. neochilus methanol extract (76.4 ± 2.09%), P. ecklonii aqueous extract inhibited (75.59 ± 6.5%) and rosmarinic acid (44.78 ± 4.53%), in comparison with epigallocatechin gallate (93.1 ± 5.27%). In contrast to the results of the previous enzymatic assays, the anti-elastase assay revealed that in general the extracts did not decrease elastase activity (30-42%). Nonetheless, the isolated compounds were tested, and they were able to highly inhibit elastase activity. Particularly, the oleanolic:ursolic acids mixture (1:4) with 63.4 ± 2.56% and Parvifloron D with 52.8 ± 3.76%, were the most efficient in elastase inhibition specially compared with ursolic acid used as positive control (69.9 ± 3.65%). The anti-inflammatory assay was performed by the quantification of NO production using the Griess reaction. The non-cytotoxic isolated compounds revealed to be unable to reduce NO production, after LPS stimulated inflammation (ranging from 16-23 μM), in comparison with the normal quantities of NO production within the cells (17.7 ± 0.67 μM), and with the positive control L-NAME that decreased NO until reaching 3.9 ± 0.24 μM. Finally, the preliminary results of Mycobacterium tuberculosis H37Rv growth assay, revealed low CFU/mL (dilution 10-3) especially regarding one halimane diterpene compound (2.1×105 CFU/mL), similar to the positive controls isoniazid (1.2×105 CFU/mL), and ethambutol (2.0×105 CFU/mL), suggesting a potential alternative for further anti-tubercular studies. Overall, according to the references of this study, this was the first report on Plectranthus spp., concerning the assays of skin-related enzymatic inhibition in vitro, anti-inflammatory assay, and Mycobacterium tuberculosis H37Rv growth, with a preliminary scientific validation upon known ethnopharmacological uses. |
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| Autores principais: | Andrade, Joana Eulália da Cruz Marçalo de |
| Assunto: | Plectranthus spp. Anti-inflammatory Antioxidant Skin enzymatic inhibition Mycobacterium tuberculosis 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: | This dissertation focused on the biological activity screening of several Plectranthus spp. plants, aiming to unravell novel ethnopharmacological roles and further research, of several extracts (methanol, ethyl acetate, acetone and water) and isolated compounds. Previous evidences on interesting biological activities of Plectranthus spp. constituents, directed the study for antioxidant, anti-skin ageing, anti-inflammatory, and anti-mycobacterial activities. Antioxidant results revealed an increased activity of the methanol extracts (20-76%), due to the presence of polyphenols widely known as antioxidants. Moreover, P. grandidentatus (62.3 ± 0.43%) and P. ecklonii (55.5 ± 1.66%) registered a high scavenging activity in the ethyl acetate extract, in comparison with quercetin (89.0 ± 2.5%), most likely due to the presence of abietane diterpenes. Acetylcholinesterase (AChE) was studied in vitro to evaluate the enzymatic inhibition, due to recent discoveries on non-neuronal cholinergic system in the skin. This assay showed that the Plectranthus spp. organic extracts did not significantly inhibited AChE. Concerning the tyrosinase inhibition assay, it was observed a high inhibition for the P. ecklonii methanol (65.9 ± 3.42%), P. grandidentatus acetone (67.9 ± 3.55%), and P. saccatus acetone (56.5 ± 5.68%) organic extracts. On the other hand, the aqueous extract of P. porcatus was the only one that showed enzymatic inhibition (65.0 ± 8.67%). From the tested isolated compounds, abietane diterpenes, mainly present in the organic extracts of P. grandidentatus, P. madagascariensis, and P. ecklonii were highly active against tyrosinase, in more than 46% and up to 75%, especially compared to kojic acid (92.9 ± 7.28%). In the collagenase assay, all tested extracts and compounds showed a high enzymatic inhibition which was in the range of 28-76%. The higher inhibition results were obtained from P. neochilus methanol extract (76.4 ± 2.09%), P. ecklonii aqueous extract inhibited (75.59 ± 6.5%) and rosmarinic acid (44.78 ± 4.53%), in comparison with epigallocatechin gallate (93.1 ± 5.27%). In contrast to the results of the previous enzymatic assays, the anti-elastase assay revealed that in general the extracts did not decrease elastase activity (30-42%). Nonetheless, the isolated compounds were tested, and they were able to highly inhibit elastase activity. Particularly, the oleanolic:ursolic acids mixture (1:4) with 63.4 ± 2.56% and Parvifloron D with 52.8 ± 3.76%, were the most efficient in elastase inhibition specially compared with ursolic acid used as positive control (69.9 ± 3.65%). The anti-inflammatory assay was performed by the quantification of NO production using the Griess reaction. The non-cytotoxic isolated compounds revealed to be unable to reduce NO production, after LPS stimulated inflammation (ranging from 16-23 μM), in comparison with the normal quantities of NO production within the cells (17.7 ± 0.67 μM), and with the positive control L-NAME that decreased NO until reaching 3.9 ± 0.24 μM. Finally, the preliminary results of Mycobacterium tuberculosis H37Rv growth assay, revealed low CFU/mL (dilution 10-3) especially regarding one halimane diterpene compound (2.1×105 CFU/mL), similar to the positive controls isoniazid (1.2×105 CFU/mL), and ethambutol (2.0×105 CFU/mL), suggesting a potential alternative for further anti-tubercular studies. Overall, according to the references of this study, this was the first report on Plectranthus spp., concerning the assays of skin-related enzymatic inhibition in vitro, anti-inflammatory assay, and Mycobacterium tuberculosis H37Rv growth, with a preliminary scientific validation upon known ethnopharmacological uses. |
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