Publicação
Evaluation of the neuroprotective effect of medicinal plants
| Resumo: | Given their therapeutic activity, natural products have been used in traditional medicines throughout the centuries. The growing interest of the scientific community in phytopharmaceuticals has resulted in a significant number of research efforts towards in understanding their effect in the potential treatment of neurodegenerative disorders. An approach to develop new ways of treatment concerns facing the context of neuroinflammation/oxidative stress on these group of diseases. This regards to a pre-pathological condition characterized by a chronic and systemic oxidative stress associated to a mild-subclinical chronic inflammation which causes neuronal cell loss. Thus, by reverting and/or attenuating this state, natural products can prevent and treat neurodegenerative diseases through modulation of microglia, the cells from brain innate system, inhibiting or reducing its inflammatory or oxidative status. The main goal of this work is to evaluate the pharmacological potential of plants used in Traditional Chinese Medicine as Hemerocallis citrina and Dendrobium nobile extracts, as well as Panax ginseng compounds and alkaloids from Nelumbo nucifera, regarding to its anti-inflammatory and antioxidant properties. For that, the scavenging activities on DPPH and NO radicals as well as the anti-acetylcholinesterase activity were evaluated. In silico methods were carried out to perform structure-activity relationships of pure compounds. Moreover, using a BV2 murine microglia cell line, the following parameters were evaluated: i) their citoxicity; ii) their antioxidant potential evaluating their ability in reverting oxidative insults and iii) their anti-inflammatory potential evaluating the capacity in decreasing proinflammatory compounds after inflammatory stimulation (bacterial lipopolysaccharide) . Finally, phytochemical analysis was performed for the extracts in order to characterize them. Although Dendrobium nobile extract and Nelumbo nucifera alkaloids have DPPH and NO radical-scavenging activity, as well as weak antiacetylcholinesterase activity, their toxicity in the BV2 cells did not enable their study in subsequent assays. Moreover, Panax ginseng compounds have been shown to have antioxidant and anti-inflammatory properties, mostly through indirect effects, probably through regulation of genetic machinery. In addition, our studies and others indicated that, in most cases, the sugar groups may not be necessary for the biological and pharmaceutical activity. In the end, all planned assays were carried out with extracts of Hemerocallis citrina. Its high content of phenolic and flavonoid acids such as caffeoylquinic acids, quercetin and apigenin derivatives can contribute to its antioxidant and anti-inflammatory activity. This last activity seems to be related to a decrease in the expression of pro-inflammatory cytokines and in the nitric oxide-producing enzyme, iNOS. Eventually, these extracts may have a therapeutic potential in living organisms in reversing neuroinflammation / oxidative stress and in the treatment of neurodegenerative diseases. |
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| Autores principais: | Silva, Ana Rita Guimarães Machado Vaz da |
| Assunto: | Ciências Naturais::Outras Ciências Naturais |
| Ano: | 2020 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Given their therapeutic activity, natural products have been used in traditional medicines throughout the centuries. The growing interest of the scientific community in phytopharmaceuticals has resulted in a significant number of research efforts towards in understanding their effect in the potential treatment of neurodegenerative disorders. An approach to develop new ways of treatment concerns facing the context of neuroinflammation/oxidative stress on these group of diseases. This regards to a pre-pathological condition characterized by a chronic and systemic oxidative stress associated to a mild-subclinical chronic inflammation which causes neuronal cell loss. Thus, by reverting and/or attenuating this state, natural products can prevent and treat neurodegenerative diseases through modulation of microglia, the cells from brain innate system, inhibiting or reducing its inflammatory or oxidative status. The main goal of this work is to evaluate the pharmacological potential of plants used in Traditional Chinese Medicine as Hemerocallis citrina and Dendrobium nobile extracts, as well as Panax ginseng compounds and alkaloids from Nelumbo nucifera, regarding to its anti-inflammatory and antioxidant properties. For that, the scavenging activities on DPPH and NO radicals as well as the anti-acetylcholinesterase activity were evaluated. In silico methods were carried out to perform structure-activity relationships of pure compounds. Moreover, using a BV2 murine microglia cell line, the following parameters were evaluated: i) their citoxicity; ii) their antioxidant potential evaluating their ability in reverting oxidative insults and iii) their anti-inflammatory potential evaluating the capacity in decreasing proinflammatory compounds after inflammatory stimulation (bacterial lipopolysaccharide) . Finally, phytochemical analysis was performed for the extracts in order to characterize them. Although Dendrobium nobile extract and Nelumbo nucifera alkaloids have DPPH and NO radical-scavenging activity, as well as weak antiacetylcholinesterase activity, their toxicity in the BV2 cells did not enable their study in subsequent assays. Moreover, Panax ginseng compounds have been shown to have antioxidant and anti-inflammatory properties, mostly through indirect effects, probably through regulation of genetic machinery. In addition, our studies and others indicated that, in most cases, the sugar groups may not be necessary for the biological and pharmaceutical activity. In the end, all planned assays were carried out with extracts of Hemerocallis citrina. Its high content of phenolic and flavonoid acids such as caffeoylquinic acids, quercetin and apigenin derivatives can contribute to its antioxidant and anti-inflammatory activity. This last activity seems to be related to a decrease in the expression of pro-inflammatory cytokines and in the nitric oxide-producing enzyme, iNOS. Eventually, these extracts may have a therapeutic potential in living organisms in reversing neuroinflammation / oxidative stress and in the treatment of neurodegenerative diseases. |
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