Authors:A. B. A. Ahmed, A. S. Rao, M. V. Rao, and R. M. Taha
Gymnemic acid (GA), a well known anti-diabetic compound has been detected in methanol extracts of intact leaves and in vitro callus cultures derived from leaf explants of Gymnema sylvestre. Callus biomass was developed in MS medium with optimum plant growth regulators (OPGRs) of 2,4-D (1.5 mg L−1) + KN (0.5 mg L−1) under abiotic stress conditions at 45 days determined by growth curve analysis. GA detection and quantification were carried out using thin-layer chromatography (TLC), highperformance thin-layer chromatography (HPTLC), high-performance liquid chromatography (HPLC), and gravimetric techniques. GA detection peak area and their absorption spectra were evaluated through HPTLC and HPLC with the standard GA. Quantification of GA had showed the linearity, accuracy, robustness and precision by HPLC. GA content was significantly higher in gravimetric method than HPLC. All these methods were found to be simple, accurate, selective and rapid and could be successfully applied for the determination of GA. It could have potential as a pharmaceutical drug for Type 1 diabetes mellitus (IDDM) and obesity.
Authors:Maha M. Abdelrahman, Nada S. Abdelwahab, Ahmed A. Taha, and John M. Boshra
The presented study was intended to design two validated, simple, and precise chromatographic methods for the determination of chlorzoxazone (CHZ) and diclofenac potassium (DIC) in the presence of chlorzoxazone nephrotoxic degradation product, 2-amino-4-chlorophenol (ACP) which was reported to be its main impurity. Reversed-phase high-performance liquid chromatography (RP-HPLC) was the first method where chromatographic separation was performed on ZORBAX Eclipse Plus C8 column using methanol—water—phosphoric acid (75:25:0.05, by volume) as the mobile phase at a flow rate of 1 mLmin−1. CHZ, DIC, and ACP retention times were found to be 4.26, 7.94, and 3.17, respectively, using photodiode array detector (DAD) at 230 nm. The calibration curves showed good linear relationships in the concentration ranges of 3–45 μg mL−1 for CHZ, 3–40 μg mL−1 for DIC, and 5–45 μg mL−1 for ACP. The second method was thin-layer chromatography (TLC) at which chromatographic separation was carried out on Merck TLC silica gel 60 F254 aluminum plates followed by measurement of separated bands at 230 nm and using chloroform—ethanol—triethylamine (9:1:0.1, by volume) as the developing system. The studied components were successfully separated with significantly different Rf values (CHZ, Rf = 0.63; DIC, Rf = 0.35; ACP, Rf = 0.42). Linearity was constructed in the range of 1.2–5 μg band−1 for CHZ, 0.5–4 μg band−1 for DIC, and 0.4–4 μg band−1 for ACP. The developed methods were applied to Declophen plus® capsules, and no interference from excipients was observed. The methods were validated as per the United States Pharmacopeia (USP) guidelines, and they were compared favorably with the reported method.