Psidium guajava (Myrtaceae), a common plant in Cariri region, Ceara, Brazil, as well as in various parts of the world, contains high concentrations of bioactive compounds and in many communities its parts are used for therapeutic purposes. activity carried out by DPPH method showed the mature fruits bearing the best results, whereas chelation of Fe2+ ions showed higher percentage for the immature fruit. The results obtained by lipidic peroxidation were not satisfactory. fruits at different stages of maturation. Materials and Methods Plant material fruits at Brefeldin A three maturity stages (immature, partially immature and mature) were collected in October 2012 at the Federal Institute of Education, Science and Technology of Ceara, Km Brefeldin A 15, city of Crato, CE-Brazil, under the coordinates 720’52.28″S, 3944’79.51″W. A voucher specimen was prepared and deposited under the registration number 9482 in the Drdano de Andrade Lima Herbarium of the Regional University of Cariri-URCA. Preparation of extracts The fruits were peeled, pulps removed (392.54 g of immature fruits; 603.28 g of partially mature fruits and 596.86 g of mature fruits), and milled with distilled water to prepare the aqueous extract. The yields after lyophilization were: immature pulp (55.97 g; 14.26 %), partially mature pulp (61.05 g; 10.12 %) and mature pulp (59.56 g; 9.98 %). To obtain the methanolic fractions the lyophilized aqueous extracts (5 g of each maturity stage) were fractionated with methanol. The ethanol was removed using a rotary vacuum evaporator (Model Q-344B, Quimis, Brazil) and an ultra-thermal bath (Model Q-214M2, Quimis) under room temperature and reduced pressure. The yields to the lyophilized extracts were: immature (1.45 g; 29.1 %), partially mature (1:34 g; 26.73 %) and mature (1.24 Rabbit Polyclonal to ZC3H13 g; 24.84 %). Chemical analysis Chemicals The chemicals used were of analytical grade. Tris-HCl, 1-1-diphenyl-2-pycrylhydrazyl (DPPH), thiobarbituric acid (TBA), malonaldehyde bis-dimethyl acetal (MDA), trichloroacetic acid (TCA), quercetin, rutin and phenanthroline were obtained from Sigma (St. Louis, MO, USA). Methanol (HPLC grade), ethanol, iron(II)sulphate, gallic, caffeic and chlorogenic acids were purchased from Merck (Rio de Janeiro, Brazil). The water used was purified in Milli-Q plus system from Millipore (Milford, MA, USA). The membranefilter (PRFE 0:45 mm) was obtained from Waters Co. (Milford, MA, USA). pH and acidity The determination of pH was performed using the potentiometric method under the rules of the Instituto Adolfo Lutz (1985[20]) and the total acidity was carried out according to titrimetric analysis using NaOH solution 0.1 M (Helrich, 1990[19]). Total phenols The concentration of total phenols was determined by the spectrophotometric method based on procedures described by Singleton et al. Brefeldin A (1999[35]). Varying concentrations of methanolic fractions were mixed with 200 of Folin-Ciocalteu solution 10 %10 % and 400 uL of 7.5 % sodium carbonate solution. The mixture was incubated at 45 C and reacted protected from light for 15 minutes. The blank test was simultaneously prepared using distilled water instead of the samples. The absorbance was determined in spectrophotometer with wavelength adjusted to 765 nm. The same procedure was repeated for the gallic acid used as standard for comparison of phenolic compounds. Total flavonoids The total concentration of flavonoids was Brefeldin A determined by the spectrophotometric method of aluminum chloride based on procedures described by Venkatachalam et al. (2012[37]). Concentration of the methanolic fractions were prepared in distilled water and mixed with 40 uL of sodium acetate, 0.1 M solution and 40 uL of a 10 %10 % solution of aluminum chloride. The mixture was incubated at room temperature for 45 minutes and reacted protected from light. The blank test was prepared concurrently by using distilled water instead of the samples. The absorbance was measured at wavelength of 415 nm. The same procedure was repeated to obtain the standard curve with rutin. Ascorbic acid The concentration of ascorbic acid was determined by the spectrophotometric method described in Leme Junior and Malavolta (1950[24]). 10 grams of lyophilized pulp in the three stages of maturation were immersed in the Brefeldin A oxalic acid solution at 2 %. After 24 hours of extraction, the samples.