Isolamento em escala preparativa de ácidos anacárdicos provenientes do líquido da casca da castanha do caju (LCC)

Abstract

The shells of cashew nut are raw material for obtaining cashew nut shell liquid (CNSL) , a brownish viscous substance with important applications in the chemical and pharmaceutical industry . Several compounds are found in CNSL, such as cardol, cardanol, methyl - cardol and anacardic acids (AnAc). The A nAc are compounds considered as phenolic lipids, due they have a long carbonic chain with different degrees of instauration. Studies in several sc ientific areas show positive results of A nAc for the treatment and prevention of some diseases and their vectors. Therefore, there is a need for more specific studies to monitor, quantify and isolate these compounds in the CNSL. In this work a chromatograp hic separation method was developed, able to isolate the A nAc present in the CNSL . A fractionation of the CNSL was also performed to obtain a fraction containing only A n A c . Samples of CN SL were solubilized in methanol, injected into a high performance liquid chromatograph coupled a diode array detector (HPLC – DAD), monitored at 280 nm, equipped with C 18 column , using as the mobile phase acetonitrile, H 2 O, acetic acid in isocratic mode . The chromatographic method developed showed adequate selectivity to be able to separate anacardic acids triene (15:3 ) , diene ( 15:2 ) and monoene ( 15:1) efficiently presents in the CNSL at the retention times 7.68, 11.09 and 17.85 min, respectively. For the preparative scale chromatographic conditions was used a HPLC – DAD mon itored at wavelength 280 nm, equipped with a C 18 column , using as the mobile phase methanol, H 2 O, acetic acid in isocratic mode . The method was mathematically adjusted to obtaining a greater similarity with the analytical method. The calibration curve w ith linear interval (50 to 1000 μg.mL - 1 ) and validation of the analytical method were made from the external anacardic acid standard (15: 3). The results obtained for method validation were satisfactory for intra - day (CV = 0.60 %) and inter - day (CV = 0.67 %) precision, linearity (y = 2670.8x - 26949, r 2 > 0.9998), repeatability for the retention time (CV = 1.02 %) and area (CV = 0.24 %), selectivity and limits of detection (19,8 μg.mL - 1 ) and quantification (60.2 μg.mL - 1 ). The recovery results obtained by th e purification of the anacardic acid on a preparative scale were 94.02, 87.63 and 97.35 %, for the triene, dieno and monoene, respectively . The data for purity were 99.11, 95.56 and 92.59 % , for the triene, diene and monoene, respectively. The s olvent consumption was 60.52 and 11.09 mL.mg - 1 for analytical and preparative scale, respectively. The productivity was 0.06 and 1.63 g.h - 1 by each g of adsorbent to analytical and preparative scale, respectively. The chromatographic method developed and i ts respecti ve scale - up were adequate for the quantification, monitoring and isolation of the an acardic acids present in the CNSL. The method was validated according to the required standards and the isolation of the analytical standard s was obtained with a n high degree of purity, recovery, low solvent consumption and good productivity.