Qualitative and Quantitative Determination of Organic Acids in Crude Herbal Drugs and Medicinal Herbal Preparations for Quality Control in Russian Federation by Modern Physicochemical Methods

Background: Organic acids (malic, citric, tartaric, oxalic, acetic, formic, isovaleric, ascorbic acids) make up a large group of biologically active substances and play an important role in plant and human metabolism. They are found in large quantities in the fruits of Rosaceae family medicinal plants that included in State Pharmacopoeia of the Russian Federation. Standardization of crude herbal drugs containing organic acids by modern physicochemical methods is a high-priority task. Materials and Methods: The determination of total organic acids amount was carried out in aqueous extracts from different fruits of Rosaceae family plants by galvanostatic coulometry and potentiometry methods. Galvanostatic coulometry was performed with the help of the “Expert-006” coulometer with a current of 5 mA (integrated pH meter). Iodine as an electrogenerated titrant was used for ascorbic acid determination; electro generation of hydroxide ions was carried out for determination of total organic acids amount. A potentiometer “Aquilon pH-410” with attached glass and silver chloride electrodes was used for potentiometric determination of total organic acids amount. Individual organic acids have been determined by reverse-phase high-performance liquid chromatography with ultra-violet detection (RP-HPLCUV) method. The following conditions were established: Gilson HPLC system, Alltech OA- 1000 Organic Acids (6.5×300 mm, 9 μm) chromatography column, a gradient elution mode, component A of the mobile phase is 98% (0.1% phosphoric acid, 10 mM KH₂PO₄, solution in water) with 2% acetonitrile, component B is acetonitrile, the eluent feed rate is 1 ml/min. Results: Modern physicochemical methods for the analysis of biologically active substances, organic acids, for quality control of crude herbal drugs and medicinal herbal preparations, are developed and discussed. The optimal conditions for the qualitative and quantitative organic acid analysis are selected and described taking into account modern pharmacopoeial requirements. Conclusion: Galvanostatic coulometry and potentiometry methods, as well as RP-HPLC-UV, can be successfully used in the quality control of crude herbal drugs and medicinal herbal preparations, specifically fruits of Rosaceae family plants. Development and validation of analytical methods for monitoring the content of this BAS group is an important research area in the pharmacopoeial standardization of crude herbal drugs.