Abstract Plants are well known throughout the world for their medical activities. The history of orchids used in many different countries around the world probably started with their use for medicinal purposes thanks to their therapeutic properties. The aim of this study, to investigate antioxidant and antimicrobial activity of ethanol extracts of plant and tuber parts of eight different epiphytic orchids from Turkey as well as their chemical composition. The antimicrobial screening of extracts was performed against 8 bacterial and 2 fungal species. To determine general chemical profile of them gas chromatography-mass spectrometry analysis was done. Antioxidative potentials of the species were proved based on 2,2-Diphenyl-1-picrylhydrazyl radical scavenging and ferric reducing antioxidant power assays. All tested extracts prepared from orchid species especially showed intermediate inhibition activity against Proteus vulgaris and Yersina enterocolitica. The Gas Chromatography and Mass Spectrometry results showed that the phytoconstituent contents of the samples were high. In the case of all extracts, more than 100 compounds were identified. But, distinctive differences in composition between each orchid species were not observed. A good correlation degree between the results of the two antioxidant tests was calculated. These well - determined antioxidant activity values can be attributed to the total phenolic content in terms of gallic acid equivalent, determined in a relatively high range (491.41-14082.94 mg GAE/g sample). These data show that different parts of the orchid samples obtained from Turkey with a past history have remarkable antimicrobial and antioxidant activity.

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.

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.