S. Thenesh Kumar, Oshin Sebastian, C. R. Sudharson


Objective: The main purpose of this study is to assess quantitatively, the effect of the addition of hydrotropes, namely urea, sodium salicylate, and sodium benzoate on the solubility of forskolin in water, and to compare the efficacy of hydrotropes in increasing aqueous solubility of forskolin. Hydrotropes were chosen for this study, based on their wavelengths, and physical properties.

Methods: The maximum wavelength of absorption of forskolin was determined spectrophotometrically, using a UV-Vis spectrometer. It was found to be 220 nm and was instrumental in the selection of hydrotropes for this experiment. Physical properties (viscosity, specific gravity and surface tension) of the chosen hydrotropes, namely sodium salicylate, urea, and sodium benzoate, were measured, over a range of concentrations and they indicated the approximate value of the minimum hydrotrope concentration of each hydrotrope. Stock solutions (1M) of the hydrotropes chosen, were prepared, and this was followed by, preparation of standard samples of forskolin, in hydrotropic solutions. These samples were analyzed spectroscopically, to obtain the characteristic calibration curves, for each hydrotrope. Solubility studies were then conducted, and the data obtained, was used to calculate enhancement ratios, which is a measure of the efficacy of a hydrotrope, in increasing aqueous solubility of a solute.

Results: The addition of hydrotropes showed a remarkable increase in aqueous solubility of forskolin. Sodium salicylate proved more effective registering an enhancement ratio of 297.02, compared to sodium benzoate, which recorded a ratio of 296.97 and urea which showed a ratio of 43.35.

Conclusion: Sodium salicylate and sodium benzoate showed very high enhancement ratios when compared to urea. This enhanced performance can be attributed to the large number of carbon atoms and the cyclic structure, which increases the hydrophobic nature of the hydrotrope. Higher efficacy of sodium salicylate can be ascribed to, the presence of hydroxyl group which increases the aqueous solubility of sodium salicylate, leading to better hydrotropic action.

Keywords: Forskolin, Hydrotropy, Solubility, UV Spectrometry, Sodium salicylate, Sodium benzoate, Urea

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International Journal of Applied Pharmaceutics
Vol 8, Issue 2, 2016 Page: 1-4

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Authors & Affiliations

S. Thenesh Kumar
Department of Chemical Engineering, S R M University, Kattankulathur, Chennai 603203, India

Oshin Sebastian

C. R. Sudharson