Evaluation of Fungi Toxic Activity of Tannins and a Tannin-Copper Complex from the Mesocarp of Cocos Nucifera Linn

María Guadalupe Lomelí Ramírez, Héctor Guillermo Ochoa Ruiz, Fernando Navarro Arzate, Martha Alejandra Cerpa Gallegos, Salvador García Enriquez

Abstract


The fibrous envelope of the coconut tree is an agroindustrial waste product that possesses relevant properties, such as a high resistance to biological degradation, because of its phenolic compound composition. In this study, the fungitoxic activity of tannins and a tannin-copper complex from the mesocarp of Cocos nucifera Linn was conducted. An extract from the coconut mesocarp was obtained in acidic media using a 2.0 wt % solution of NaHSO3. Bioassays were conducted on alder wood (Alnus acuminata ssp. glabrata H.B.K.) using two types of aqueous solutions: 1) crude extract from the coconut mesocarp diluted at several concentrations (0.5, 1.0, 2.0, and 4.0 wt %); and 2) a tannin-copper complex formed in two stages by impregnation of the alder wood samples, first with the coconut mesocarp extract solutions followed by addition of a CuCl2 solution. The fungitoxic capacity of the tannin and tannin-copper complex solutions was evaluated by means of bioassays with Trametes versicolor (L. ex. Fr.) Pilát according to ASTM D 1413-07. The bioassays showed poor fungal inhibition for the wood samples impregnated with the crude extract solutions. However, the tannin-copper complex solutions showed greater fungal inhibition. Retention values of 4.03 and 1.76 kg m-3 were obtained. These values revealed high fungal inhibition for Trametes versicolor.

Keywords


<i>Cocos nucifera</i> Linn;tannin;tannin-copper complex;decay;xylophagus fungi

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