ABSTRACT
The quality and quantity of metabolites in plants responsible for biological activities are influenced by a multitude of factors, chief among them, environmental. Furthermore, part of the plant to be tested and selected extraction solvent affect these kinds of activities. Ethanol and water extracts of above ground and below ground parts of the Ornithogalum sigmoideum Freyn & Sint. collected from different altitudes of Ordu province at two different period (begining and end of flowering) were studied in terms of phenolic contents and antioxidative activities. Thus, the effect of four different factors (altitude, flowering period, plant section, extraction solvent) on these parameters were examined. Both the main effects and the interactions of these factors were evaluated separately, and it was concluded that quaternary interaction was statistically significant on the antioxidant activity tested according to the ferric reducing antioxidant power (FRAP) method. Binary interactions such as altitude*solvent and section*solvent were statistically significant on total phenolic content values. On the other hand, section*solvent and altitude*period*section interactions were statistically significant for 2,2-diphenyl-1- picrylhydrazyl (DPPH) scavenging activity.
ABSTRACT
ABSTRACT Objective The purpose of this study is to determine the phenolic and flavonoid contents, and antioxidant activities and neuroprotective effects of powdered coffee sample of a commercial coffee brand originated from Sivas, Turkey. Methods Total phenolic, flavonoid and antioxidant contents, enzymatic and non-enzymatic antioxidative activities based on 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity, metal chelating potential, reducing power, superoxide dismutase and catalase activity tests and lipid peroxidation inhibition potentials of the ethanolic and aqueous extracts of the coffee sample were assayed using the commonly preferred spectrophotometric methods. Furthermore the extracts' cholinesterase and tyrosinase inhibition potentials were evaluated. Phenolic profiles of the coffee sample were investigated using high performance liquid chromatography. Results Catechin was the most frequently detected phenolic acid. In addition, it was demonstrated that the water extract has a significant impact when compared with standard antioxidants. While the SC50 (sufficient concentration to obtain 50% of a maximum scavenging capacity) value for the scavenging activity of 2,2-diphenyl-1-picrylhydrazyl free radical was calculated as being 0.08mg/mL for water extract, the amount of chelating agents with half Fe2+ ions in the medium was found to be 0.271mg/mL. Additionally, it was shown that 0.1mg/mL concentration of both extracts prevents lipid peroxidation by 8%. Compared with standard drugs, inhibition potentials of cholinesterase and tyrosinase enzymes were considered as moderately acceptable in these samples. Conclusion Besides the extracts' enzymatic antioxidant activity, their inhibition potential on cholinesterase and tyrosinase enzymes - which are important clinical enzymes - reveal that this natural source can be used as a valuable resource in different fields, especially in medicine.
RESUMO Objetivo O objetivo deste estudo é determinar o conteúdo fenólico e flavonoide, bem como as atividades antioxidantes e os efeitos neuroprotetores de uma amostra de café em pó de uma promissora marca comercial proveniente de Sivas, Turquia. Métodos A partir dos métodos espectrofotométricos comumente utilizados, foram analisados os seguintes aspectos da amostra de café: teores de fenólicos totais, flavonoides e antioxidantes; atividades antioxidantes enzimáticas e não enzimáticas, baseadas na atividade de eliminação de radicais livres de 2,2-difenil-1-picrilhidrazila potencial quelante de metais; poder redutor; testes de atividade de superóxido dismutase e catalase; e potenciais de inibição da peroxidação lipídica dos extratos etanólicos e aquosos. Além disso, foram avaliados os potenciais de inibição da colinesterase e da tirosinase dos extratos. Os perfis fenólicos da amostra de café foram investigados por cromatografia líquida de alta eficiência. Resultados Entre os ácidos fenólicos estudados, o mais detectado foi a catequina. Especialmente, foi demonstrado que o extrato de água tem um impacto significativo quando comparado com os antioxidantes padrão. Determinou--se que o valor de SC50 (a concentração suficiente para obter 50% da capacidade máxima de eliminação) da atividade de eliminação do radical 2,2-difenil-1-picrilhidrazilab/para extrato de água era de 0,08mg/mL, enquanto a quantidade de agentes quelantes com metade de Fe2+ íons na média foi encontrada como 0,271mg/mL. Também foi demonstrado que a concentração de 0,1mg/mL de ambos os extratos inibe a peroxidação lipídica em cerca de 8%. Comparado com drogas padrão, os potenciais de inibição das amostras nas enzimas e tirosinase foram aceitáveis como moderados. Conclusão Os resultados mostram que, além de terem atividade antioxidante enzimática, os extratos apresentam potencial de inibição das enzimas colinesterase e tirosinase, que são importantes enzimas clínicas, o que revela que essa fonte natural pode ser usada como um recurso valioso em vários campos, principalmente na medicina.