Physicochemical characterization of herbal drug from bole and solid waste resulting from decortication of Agave sisalana leaves

Only 5% of the whole mass from decortication of Agave sisalana Perrine leaves, which is constituted by a hard fiber, is exploited, while the remaining 95% consisting of solid and liquid wastes is normally discarded by sisal farms. Studies demonstrated the potential of products from A. sisalana in different pharmaceutical applications, but the quality of herbal raw materials is essential to reach the desired specifications of intermediate and final products. The aim of this work was to analyze physicochemical quality parameters of materials and extracts from bole and solid waste from A. sisalana collected in Monteiro, Paraíba-PB. Materials were dried in a forced circulation oven at 40°C up to constant weight to obtain herbal drugs from bole (HDB) and solid waste (HDSW). Both HDB and HDSW were extracted with distilled water by dynamic maceration at 80°C for 2 hours (7:1 w/v) to obtain the corresponding liquid extracts (HDB-LE and HDSW-LE, respectively). Physicochemical analyses were done according to pharmacopoeia methods either on materials (pH, particle size, density, loss on drying and ash content) or extracts (pH, dry residue, density by pycnometer, °Brix and spectrophotometric scanning at 200-800 nm). Since HDSW had larger particles size than HDB, the fact that the HDSW-LE volume (206.5 mL) was lower than that of HDB-LE (268.0 mL) under the same extraction conditions suggests a direct influence of the extraction protocol on the efficiency, as reported in the literature. Higher values of density (0.55 g.mL-1 ± 0.03) and water content (6.62 % ± 0.12) for HDSW-LE compared with HDB-LE (0.43 g.mL-1 ± 0.01 and 4.33 % ± 0.15, respectively) may reflect the larger particle size of HDB. Ash content of HDSW (16.62 ± 0.07%) was higher than that of HDB (6.43 ± 0.12%), thereby pointing out the presence of impurities resulting from decortication. The extraction efficiency from HDSW (31.5 % ± 9.1) was remarkably lower than from HDB (79.3 % ± 18.5), likely due to the high content in water-soluble carbohydrates of agave species boles. This inference seems to be confirmed by the higher values of °Brix (5.47 ± 0.55) and dry residue (6.14 % ± 0.38) for HDB-LE compared with HDSW-LE (2.3 ± 0.52 and 2.48 % ± 0.16, respectively). Spectrophotometric scanning suggested different compositions of these extracts. The quality control parameters established for A. sisalana in this study could be of some interest to guarantee quality and safety in herbal medicine.