Bioactive aqueous extract of Nigella sativa L. seed waste: Formulation and evaluation

The bioactive aqueous extract of Nigella sativa L. seed waste was formulated into soft gelatin capsules (Su1-Su6) in a dose of 200 mg/kg b. w. using different pharmaceutical excipients: soya lecithin/ span80/ sodium taurocholate, PEG 400, and Meglyol 810. The formulations were evaluated for their immunostimmulant and hepatoprotective activities using biochemical methods and for their release by dissolution studies according to USP XXII. Formula Su3 showed a potent effect by significantly reducing tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (INF-γ) and interlukin-beta (IL-1β) levels compared to CCl4-treated animals. A significant reduction in the glutamic pyruvic transaminase (GPT) and bilirubin levels and a decrease in both lipid peroxidases (LP) and glutathione content (GSH) have been noticed when compared to CCl4-treated mice. Formula Su3 revealing the highest activity and optimum release, was selected and coated with two films – coating solutions (Su3: Eu. L-100, Su3: Eu. S100) for site-specific delivery and sustained release. Eudragit L-100 and Eudragit S-100 were selected as coating materials and PEG 4000 as plastifing agent. Dissolution and disintegration tests were carried out for coated Su3 in order to verify the gastric-resistant properties of the coated product in simulated gastric medium (SGM) at pH 1.2 for 2 h and in simulated intestinal medium (SIM) at pH 7.4 for additional 2 h using a normal basket-rack. Quality control of the formulated extract, either uncoated or coated was performed using protein as active marker by adopting Bradford protein assay for comparison with plain extract in both SGM and SIM.