Abstract The present study analyzes the relationship between people and plants in the caatinga region of Northeastern Brazil, considering the influence of socio-economic factors on different categories of plant use in the community. Thus, it aims to associate socio-economic factors and knowledge in the use dynamics of medicinal, food and timber plants in Brejo da Conceição community, Currais, Piaui, Brazil. The data set was obtained through semi-structured interviews, interviewing one-hundred-one persons: 46 women and 55 men. A generalized linear model analyzed socio-economic factors influencing the knowledge of plants, built using Poisson distribution and having as explanatory variable age, gender, number of residents in household and education; as a response variable, the number of plants cited per respondent. To better understand the distribution of plants in use categories, we verified which species are the most important locally and, for that, we calculated the plants’ Cultural Importance Index and Relative Importance Index. The interviewees cited 126 plant species. Among these species, 74 were native, and 52 were naturalized. Overlapping the categories of use, the most prominent species in the categories medicinal and food, according to the indices of cultural importance (CI) and relative importance (RII), were the buriti palm tree (Mauritia flexuosa L.f.), orange (Citrus sinensis (L.) Osbeck) and cashew (Anacardium occidentale L.). For the overlap of medicinal and timber uses, catinga de porco stood out (Terminalia brasiliensis (Cambess.) Eichler) and birro de cangalha (Diplopterys sp.). The lemon balm herb stood out as its medical use (Lippia alba (Mill.) N.E.Br. ex Britton & P.Wilson). Just the number of residents and gender factors influenced the plants’ knowledge of Brejo da Conceição in medicinal use, food and wood resources. Given the complexity of current discussions that guide related to these characteristics, the proposed results can serve as a reference for future research that incorporates more aspects of local ecological knowledge, including analyzing other essential variables that shape the distribution of knowledge in the distinct categories of use. Brazil socioeconomic socio economic community Thus Currais Piaui semistructured semi structured interviews onehundredone one hundred persons 4 5 men age education respondent 12 7 native naturalized CI (CI RII, RII , (RII) Mauritia L.f., Lf L.f. L f L.f.) Citrus L. (L. Osbeck Anacardium L.. . L.) uses Terminalia Cambess. Cambess (Cambess. Eichler Diplopterys sp.. sp sp. sp.) Lippia Mill. Mill (Mill. NEBr N E Br N.E.Br P.Wilson. PWilson P.Wilson P Wilson P.Wilson) resources characteristics 1 (RII L.f (L (Cambess (Mill

O teor de taninos em três espécies medicinais do semi-árido do Nordeste do Brasil foi determinado. A partir de amostras das cascas do caule e folhas de 10 indivíduos de Anadenanthera colubrina (Vell.) Brenam, Myracrodruon urundeuva (Engl.) Fr. All. e Caesalpinia pyramidalis Tul., os teores de fenóis totais e taninos foram determinados em extratos metanólicos 80% pelo método de Folin-Ciocalteau, seguido do método da precipitação de proteínas. Adicionalmente, testou-se a hipótese de que a concentração de taninos está diretamente relacionada com a altura e diâmetro das plantas. As espécies estudadas apresentaram expressivos teores de extrativos tânicos, e os resultados não ratificaram a hipótese testada.

A comparative study of tannin concentration in three medicinal plants from caatinga vegetation (Northeast Brazil) was carried out through colorimetric assays. Bark and leaf samples of 10 individuals of each species were extracted with 80% methanol. Tannin was determined by Folin-Ciocalteau analysis for total phenolic materials, followed by precipitation with casein. Additionally, it was tested the hypothesis that the tannin concentration is directly related with the height and diameter of the plants. The results show that the studied species contain an expressive amount of tannins.