1 2 Original Research Article 3 4 Tannin content of the bark and branch of Caatinga 5 species 6 7 8 ABSTRACT 9 This research aimed to determine the concentration of tannins in the bark and in the branches of ten species of Caatinga occurrence species. The study was carried out at the Laboratory of Plant Biochemistry of the Federal Rural University of Pernambuco. The Folin-Denis colorimetric method was used to determine the phenol content and the tannins are precipitated using a protein. The tannin content was obtained by the difference between the supernatant and the non-tannic phenol content. The data were subjected to an Analysis of Variance using a 2x10 factorial design and Turkeys’s test was used to detect differences. For bark sample, the species Parapiptadenia zehntneri, Parapiptadenia rigida and Libidibia ferrea presented the three highest percentages among the studied species, being 10.84%, 10.74% and 10.27%, respectively. For branch sample, Aspidosperma pyrifolium presented the highest percentage of tannins among the ten species, with 9.15% of these substances. Thus, it is possible to suggest the use of other parts of the tree to extract the tannins, such as the branches and their bark, offering an alternative for the extraction that is usually made from the main trunk and providing sustainability to the Caatinga. 10 11 Keywords: non-timber forest product; wood extractives; chemical composition and Brazilian semiarid Comment [AL1]: You have to avoid *and* in 12 Keywords. Correct it. 13 1. INTRODUCTION 14 15 Non-timber forest products (NTFPs) have been of great importance over time, as the reasons for this, 16 one can cite their association with rural communities. They are considered as agricultural products 17 and can be sold informally among the communities themselves, so they can be left out of statistics 18 and not treated with great prospects. 19 The northeastern Brazilian region has a range of products that can be used from the diversity of 20 species, generating employment and income. In addition, these products can assure the feeding of 21 the families, as these products have great possibility of use. These products can supply not only the 22 communities in the extraction areas but also the urban populations of large cities, including those in 23 other countries [1]. 24 More than 70 plant species were cataloged in the Caatinga, which have potential for use as NTFPs, 25 of which 18 are highlighted as being of intensive use. Among them, species such as Libidibia ferrea, 26 Myracrodruon urundeuva and Tabebuia aurea, are examples of species considered to be of priority of 27 use by communities for different purposes. However, the latter two are considered rarer species, 28 requiring tighter control in their exploitation to prevent extinction [2]. 29 Among the most well-known NTFPs, the tannins are highlighted, included in the group of phenolic 30 compounds present in wood. They can be defined as substances that have the capacity to precipitate 31 proteins and can be classified as natural or synthetic according to their origin [3]. 32 The tannins are responsible for conferring the astringent flavor on some fruits, the plants use these 33 substances for defense against fungi and other pathogens, due to their toxicity, which stimulates their 34 use also as a natural preservative. The species exploited for their high percentage of tannic 35 substances are generally used for medicinal purposes, aging of cachaças and wines, in leather 36 tanning process, manufacture of adhesives and paints [3,4,5]. 37 The tannin content varies according to the species, as well as their age, part of the plant collected, 38 season and place of collection, but in general the highest percentages are in the bark and leaves [6]. 39 Studies show that, in addition to the trunk, other parts of the trees may contain a number of tannins 40 that can be extracted for use in, for example, the industry [7]. 41 Some studies carried out with Caatinga species that presented considerable levels of potential 42 tannins for extraction were M. urundeuva, for medicinal use and leather tanning; P. pyramidalis for its 43 anti-inflammatory, antioxidant and antimicrobial properties; P. rigida and P. zehntneri, present a high 44 percentage of tanantes substances, which confers resistance to the attack of xylophages [8,9,10,11]. 45 This research aimed to determine the concentration of tannins in the bark and in the branches of ten 46 species of Caatinga occurrence species. 47 48 2. MATERIAL AND METHODS 49 50 2.1 Study Area Characterization 51 52 The material was collected in the city of Piranhas (9º 37 'S and 37º 46' W, altitude of 110 m), located 53 in the State of Alagoas, located in the Meso-region of the Sertão and Alagoana Microregion of the 54 São Francisco Region. The city has a Tropical semiarid climate, according to the Köppen 55 classification, with an average rainfall of 492.2 mm / year and and - average annual air temperature of Comment [AL2]: correct 56 26.6 °C [12]. 57 Branches of the following species were used for the research: Parapiptadenia zehntneri (Harms) 58 M.P.Lima & Lima), Parapiptadenia rigida (Benth.) Brenan, Myracrodruon urundeuva Allemão, Mimosa 59 hexandra Micheli, Poincianella pyramidalis (Tul.) L.P. Queiroz, Tabebuia aurea (Silva Manso) Benth. 60 & Hook. f ex S. Moore, Commiphora leptophloeos (Mart.) J.B. Gillett, Erythrina velutina Wild., Libidibia 61 ferrea (Mart. ex Tul.) L.P. Queiroz and Aspidosperma pyrifolium Mart. & Zucc. All the species used 62 are of occurrence of the Caatinga biome and were chosen from the use history for de extraction of 63 non-timber forest products. The branches were collected from adult trees, 64 during the summer, from an area of managed native forest. No information is available regarding the 65 age of the trees. 66 67 2.2 Sample Preparation 68 69 The tannins were then extracted according to the methodology described by [4] under controlled Comment [AL3]: Methodology is the systematic, 70 laboratory conditions. The barks were removed from the branches with the help of knives and theoretical analysis of the methods applied to a field 71 reduced to smaller pieces. The branches were fragmented and then milled in a knife mill (Willey) with of study. It comprises the theoretical analysis of the body of methods and principles associated with a 72 a 2 mm particle selection screen to obtain sawdust. After processing, the materials were packaged in branch of knowledge. 73 hermetically sealed containers and kept at room temperature. 74 You use the method. 75 2.3 Obtaining the Plant Extract Comment [AL4]: Values of temperature, 76 humitidy, pressure? 77 For the preparation of the plant extracts, 0.2 g of sawdust or barks were used, to which 20 mL of Comment [AL5]: Value? 78 ethanol (80%) in Erlenmeyer flask were added, remaining for a period of 30 minutes under constant 79 agitation. The extract obtained was filtered on filter paper into a 50 ml volumetric flask, then the 80 residue was washed and the volume of the flask filled with distilled water. Five replicates were 81 performed for each sample, for both bark and branches. The extract was homogenized and Comment [AL6]: For each species? 82 transferred to a bottle, identified and kept refrigerated until the following ingredients were used. 83 84 2.4 Determination of Total Phenolic Compounds 85 86 For the determination of total phenols, the following solutions were used: saturated sodium carbonate 87 solution, standard tannic acid solution, dilute standard solutions and the Folin-Denis reagent. All of 88 them were previously prepared. 89 Using a pipette, 0.2 ml of standard tannic acid solution (concentrations: 25, 50, 100 and 200 mg.L-1) 90 was transferred to a tube, then 5 ml of distilled water, 1.0 ml of saturated sodium carbonate solution 91 (350 g / L) and 0.5 ml of the Folin-Denis reagent were also added in the tube. The same procedure 92 was performed for the plant extracts obtained in step 2.3. 93 The spectrophotometric reading of the vegetable extracts and standard solutions was performed in 94 the 760 nm range, using a spectrophotometer (Spectrum brand, model SP 1105 335 at 1000 nm), to 95 obtain the absorbance values and the standard curve preparation. 96 97 2.5 Tannin Precipitation 98 99 After the determination of the total phenols, the same samples were used to precipitate the tannins, 100 adding in each one 50 mg of protein (bovine serum albumin), responsible for reacting with the tanic 101 substances and performing the precipitation. The tube was sealed and shaken for one minute. The 102 mixture was allowed to stand for a period of 24 hours in a refrigerator and then centrifugation was 103 performed for 10 minutes at a speed of 2000 rpm. Then, the spectrophotometric reading of the plant Comment [AL7]: rotation speed 104 extracts was made, also in the 760 nm range, was carried out to determine the supernatant. 105 From the supernatant the total non-tannin phenols content was determined. The tannins present were 106 calculated by difference between the supernatant and the precipitate. 107 108 2.6 Experimental Design and Statistical Analysis 109 110 For the statistical analysis, the software Assistat 7.7 beta was used. The results were submitted to 111 Variance Analysis, considering a factorial 2x10, where the sources of variation were the parts of the Comment [AL8]: Do you know when you can 112 tree (bark of the branch and branch), the species and the interaction of the factors (parts of the tree x use the Variance Analysis. Did you check the 113 species).