Analysis of condensed tannins: a review

Schofield, P; Mbugua, David; Pell, Alice N.

doi:10.1016/s0377-8401(01)00228-0

Cited by 769 publications

(606 citation statements)

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“…However, other non-tannin phenolics with the same functional group may interfere to give variable values. A lack of an appropriate standard for the condensed tannin determination was also a major setback due to heterogeneity of condensed tannin and the use of vanillin as indicator may result in unrealistic values (Schofield et al, 2001). …”

Section: Phenolic Constituents Of the Crude Extractsmentioning

confidence: 99%

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Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

Ahmed

McGaw

Elgorashi

et al. 2014

Journal of Ethnopharmacology

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Graphical abstractPhenolic-enriched extracts of four Combretum species namely Combretum bracteosum, Combretum padoides, Combretum vendae and Combretum woodii used in South African traditional medicine to treat various ranges diseases were evaluated against some diarrhoeal aetiologies. All the crude extracts and their fractions of varied polarities had good antimicrobial (non-polar fractions) or good antioxidant (polar fractions) activity. The crude extract of all the plant species were cytotoxic to Vero cell lines but did not lead to COX enzyme inhibition. Phenolic-enriched extractsFour Combretum species traditionally used for treating infectious and gastrointestinal complications in southern Africa In vitro assays: antioxidant, anti-inflammation, antimicrobial, cytotoxicity AbstractEthnopharmacological importance: Infections and gastrointestinal (GIT) disorders such as diarrhoea causes many problems in human health and animal production. Many Combretum species are used in traditional medicine to treat various diseases by rural people in Africa and Asia. Much of the work done to date on some species to validate their ethnopharmacological use was on the non-polar or intermediate polarity components. Many species are yet to be studied against relevant disease parameters using more polar extracts. Aims:The polar components were extracted and fractionated by solvent-solvent fractionation to yield fractions of different polarities. The activity of these fractions on different parameters that could be involved in infectious and gastrointestinal track (GIT) disorders was investigated. The cytotoxic activities of the extracts were also determined to evaluate the potential of these extracts to combat diarrhoea in production animals. Materials and Methods:Phenolic-enriched leaf extracts of Combretum bracteosum (Cob), Combretum padoides (Cop), Combretum vendae (Cov) and Combretum woodii (Cow) were obtained by extracting with a mixture of 70% acetone acidified with 1% HCl and n-hexane. The extract was sequentially treated by solvent-solvent fractionation with dichloromethane, ethyl acetate, and butanol to yield fractions with a large variation in polarity. The phenolic constituents of the extracts and fractions were determined using standard procedures. The antioxidant activities were determined using various standard methods. The minimum inhibitory concentrations (MICs) of the crude extracts and fractions against four bacterial and three fungal strains were assessed with a microplate serial dilution method.Cyclooxygenase (COX) and lipoxygenase (LOX) enzyme inhibitory assays and cytotoxicity studies against Vero cells were also carried out.Result: Some of the fractions had much higher antioxidant activity than the positive controls. The average EC 50 values of the extracts for the DPPH and ABTS antioxidant assays were 0.21-12 µg/ml (Cop), 0.25-16 µg/ml (Cov), 0.33-9.41 µg/ml (Cow) and 4.97-85 µg/ml (Cob) respectively while the mean EC 50 values for the positive controls ascorbic acid and trolox were 1.28-1.51 and 1.02-1.19 ...

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Section: Phenolic Constituents Of the Crude Extractsmentioning

confidence: 99%

“…However, there is no appropriate standard to compare the result. The reaction is sensitive to water content, transition metal ions and the ratio of the butanol/HCl to sample in the reaction medium, therefore unreliable data may be obtained if proper precautions are not taken (Schofield et al, 2001). …”

Section: Phenolic Constituents Of the Crude Extractsmentioning

confidence: 99%

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

Ahmed

McGaw

Elgorashi

et al. 2014

Journal of Ethnopharmacology

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“…Entre os métodos colorimétricos, o método de Folin-Denis é bem reconhecido e largamente usado, mas não faz distinção entre compostos fenólicos e outros materiais redutores ou antioxidantes, como o ácido ascórbico, formando precipitados que interferem na leitura espectrofotométrica 32 . O método Folin-Denis foi aperfeiço-ado e modificado para o Folin-Ciocalteau 33 .…”

Section: Determinação Do Teor De Taninosunclassified

“…Para quantificar taninos condensados os métodos mais utilizados são o butanol-HCl e o vanilina 32,35,36 . De acordo com Schofield e colaboradores 32 , o método vanilina depende da reação da vanilina com os taninos condensados para formação de complexos coloridos.…”

Section: Determinação Do Teor De Taninosunclassified

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Taninos: uma abordagem da química à ecologia

et al. 2005

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. Prof. Nelson Chaves, s/n, 50670-901 Recife -PE Recebido em 31/3/04; aceito em 19/1/05; publicado na web em 13/4/05 TANNINS: FROM CHEMISTRY TO ECOLOGY. Tannins are compounds of great interest in chemistry and ecology. They have various effects on food digestibility and the performance of animals. In this work, the chemistry, the biological activity and the ecology of tannins are examined. A brief discussion of several analytical methods for the determination of tannins is presented.Keywords: tannins; colorimetric assay; biological activity. INTRODUÇÃOOs compostos do metabolismo secundário vegetal ou metabolismo especial apresentam um amplo valor nas interações entre a planta e seu ecossistema exercendo, por ex., o papel de fagoinibidores contra herbívoros ou como agentes antimicrobianos 1 . Como metabólitos secundários, os taninos são compostos fenólicos de grande interesse econômico e ecológico. Apresentam solubilidade em água e peso molecular compreendido entre 500 e 3000 Dalton, possuindo a habilidade de formar complexos insolúveis em água com proteínas, gelatinas e alcalóides 2 . Tais compostos são responsáveis pela adstringência de muitos frutos e produtos vegetais, devido à precipitação de glucoproteínas salivares, o que ocasiona a perda do poder lubrificante 3 .A ligação entre taninos e proteínas ocorre, provavelmente, através de pontes de hidrogênio entre os grupos fenólicos dos taninos e determinados sítios das proteínas, emprestando uma duradoura estabilidade a estas substâncias. Para a formação destas ligações é necessário que o peso molecular dos taninos esteja compreendido entre limites bem definidos; se este é demasiadamente elevado, a molécula não pode se intercalar entre os espaços interfibrilares das proteínas ou macromoléculas; se é muito baixo, a molécula fenólica se intercala, mas não forma um número suficiente de ligações que assegure a estabilidade da combinação 3 . Os taninos têm sido alvo de diversos estudos, sendo que a maioria vem abordando interações ecológicas entre vegetais e herbívoros, visto que se têm sugerido que os teores de taninos podem diminuir a taxa de predação por se tornarem impalatáveis, afastando seus predadores naturais 4-8 . Pesquisas sobre atividade biológica dos taninos evidenciaram importante ação contra determinados microrganismos 4 , como agentes carcinogênicos e causadores de toxicidade hepática 9 . Estes últi-mos efeitos, sem dúvida, dependem da dose e do tipo de tanino ingerido. A ingestão de chá verde e de dietas ricas em frutas que contêm taninos, por ex., tem sido associada com atividade anticarcinogênica 9 . Além disso, podem agir como antiinflamatórios e cicatrizantes 2 , e até como inibidores da transcriptase reversa em HIV 10 .Alguns trabalhos têm tratado do aspecto antinutricional de cultivares com altos teores de taninos e sua resistência a pragas 11,12 . Outros trabalhos têm avaliado a influência de diferentes variáveis nos teores de taninos em espécies de interesse econômico 13,14 . A sazonalidade tem sido apontada como um interessante fator para a...

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HPLC Separation of Polyphenolics

Kim

Lee

2002

Current Protocols in Food Analytical Chemistry

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The polyphenolics, ubiquitous phytochemicals in the plant kingdom, are important aromatic secondary metabolites of plants. Diverse combinations of polyphenolics are found in plant-based materials. Polyphenolics are important because they are responsible for the color and flavor of fresh and processed products. Some have strong antioxidant and anticancer activities. They are routinely consumed in the human diet in significant quantities.In this unit, methods for reversed-phase high-performance liquid chromatography (HPLC) are described for the analysis of polyphenolics. HPLC analysis can be employed in an easy and fast manner to obtain an accurate elucidation and quantification of individual polyphenolic compounds found in plant-based materials. The separation of each polyphenolic is based on the polarity differences among polyphenolics with structural similarities and uses various combinations of mobile and stationary phases.The Basic Protocol describes the reversed-phase HPLC analysis of polyphenolic compounds isolated into nonanthocyanin and anthocyanin fractions by solid-phase extraction. The Alternate Protocol describes the HPLC separation of acidic and neutral polyphenolic fractions. Fractionated samples are used because significant amounts of interfering compounds are extracted along with polyphenolics from plant materials. Solid-phase extraction with C18 Sep-Pak cartridges (UNIT I1.2) is used to selectively eliminate undesired components from crude extracts, and may minimize the effects of sample cleanup or preparation on the integrity of polyphenolics. The isolation and purification step using solid-phase extraction of polyphenolics will make possible the efficient analysis of individual polyphenolics by reversed-phase HPLC.NOTE: Deionized and distilled or HPLC-grade water should be used in these protocols. Reagents (solvetns) should also be HPLC grade.

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Analysis of condensed tannins: a review

Cited by 769 publications

References 64 publications

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

Polarity of extracts and fractions of four Combretum (Combretaceae) species used to treat infections and gastrointestinal disorders in southern African traditional medicine has a major effect on different relevant in vitro activities

Taninos: uma abordagem da química à ecologia

HPLC Separation of Polyphenolics

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