Solubility of commercial octacosanol in organic solvents and their correlation by thermodynamic models at different temperatures

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Highlights

  • Solubility data of commercial octacosanol in organic solvents were determined from 298.2 to 333.2 K.

  • Commercial octacosanol extraction can be maximized at higher temperatures and using toluene as solvent.

  • Use of alcoholic solvents with the longest carbon chain increases commercial octacosanol solubility.

  • UNIQUAC model presented the best performance in the correlation of the experimental data.

Abstract

Octacosanol is a high-molar-mass primary aliphatic alcohol that has shown promising effects in diabetes treatment and in lowering cholesterol. Although this compound has been obtained from non-saponifiable matter of vegetable materials by extraction with solvents, there are no solubility data in the literature. This study presents experimental values for commercial octacosanol solubility in three pure solvents (1-pentanol, 1-hexanol, and toluene) from 298.2 to 333.2 K. Solubility obtained in this study ranges from 0.0006 to 0.0602 in mole fractions. In addition, solid–liquid equilibrium results were correlated using four thermodynamic models: Van Laar, three-suffix Margules, NRTL, and UNIQUAC. Results show that high temperatures and the use of alcoholic solvents with the longest carbon chain or hydrocarbons are required to maximize commercial octacosanol solubility. The UNIQUAC model provides the best performance in the correlation of the experimental values; however, all thermodynamic models could be used to describe commercial octacosanol solubility.

Introduction

Policosanol is a mixture of long-chain primary aliphatic alcohols containing 20–36 carbons that is commonly found in non-saponifiable matter such as sugar cane wax and beeswax [1]. Another source of this compound is the non-saponifiable matter of vegetable oils, some of which, such as perilla seed, grape seed and rice bran oils, can provide high quantities of this compound; oils of corn germ, sesame and soybean present lower amounts of policosanol [2].

The main component of policosanol (octacosanol) can be used as a feed supplement for athletes since it improves stamina and, consequently, exercise capability [3], [4]. On the other hand, the effectiveness of policosanol as a lipid-lowering agent in hypercholesterolemia treatment is still under debate [5], [6], [7]. In this context, it is important to highlight that the mixture of higher aliphatic alcohols in policosanol can show variation, so the results of clinical trials can diverge [8].

Since long-chain primary aliphatic alcohols can be obtained using solvent extraction, it is important to have knowledge of its solubility in different solvents. However, octacosanol solubility data are not found in the literature. Presented in this work are experimental values for commercial octacosanol solubility in three pure solvents (1-pentanol, 1-hexanol and toluene) from 298.2 K to 333.2 K. The solid–liquid equilibrium is correlated using four thermodynamic models, Van Laar, Margules three-suffix, NRTL and UNIQUAC, allowing the evaluation of model performance.

Section snippets

Reagents

Commercial octacosanol was supplied by Huzhou Nanxun Shengtao Botanical Co. Ltd. (Shuanglin, Huzhou, China). 1-Pentanol (71-41-0, Merck, Germany), 1-hexanol (111-27-3, Merck, Germany), toluene (108-88-3, M-Tedia, USA), and chloroform (67-66-3, Sigma-Aldrich, USA) were used as solvents, without further purification.

The following long-chain primary aliphatic alcohols were used as standards in the characterization of commercial octacosanol: 1-docosanol (661-19-8), 1-tetracosanol (506-51-4),

Commercial octacosanol characterization

As mentioned in item 2.2, the chemical characterization of commercial octacosanol was performed aiming to determine the impurities that may be present in the reagent. In order to achieve this aim, the compounds were identified by CG-MS and NMR and quantified by CG-FID. Fig. 1, Fig. 2 show the chromatograms and mass spectra, respectively.

The GC–MS and GC-FID analysis enabled the identification and quantification of the components of commercial octacosanol as 1-octacosanol (94.83% in mass) and

Conclusions

Solid-liquid equilibrium for systems containing commercial octacosanol in three different organic solvents (toluene, 1-pentanol, 1-hexanol), from 298.2 to 333.2 K, was experimentally determined. Commercial octacosanol was successfully characterized by the GC–MS and 1H NMR techniques, which allowed us to confirm the presence of octacosanal as an impurity. The solubility values in alcohols and hydrocarbon ranged from 0.0006 up to 0.0602, in mole fractions, and it was possible to observe that

Acknowledgments

The authors wish to acknowledge Prof. Antonio Eduardo Miller Crotti (FFCLRP/USP) for his assistance in the GC–MS analysis. FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo – 07/06170-4; 08/56258-8; 14/09446-4; 14/21252-0; 15/07370-3) and CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico – 303797/2016-9), for their financial support.

References (26)

  • S. Irmak et al.

    Food Chem.

    (2006)
  • J.C. Taylor et al.

    Nutrition

    (2003)
  • W. Tang et al.

    J. Chem. Thermodyn.

    (2015)
  • D. Wei et al.

    Fluid Phase Equilibr.

    (2010)
  • M.D.A. Saldaña et al.

    J. Chem. Thermodyn.

    (2012)
  • A.P. Carneiro et al.

    J. Chem. Thermodyn.

    (2012)
  • M.C. Pérez-Camino et al.

    J. Chromatogr. A

    (2003)
  • S. Feng et al.

    Food Chem.

    (2015)
  • D.M. Jung et al.

    J. Food Sci.

    (2011)
  • H. Kim et al.

    J. Med Food

    (2003)
  • F. Francini-Pesenti et al.

    Complement. Ther. Med.

    (2008)
  • M.F. Dulin et al.

    Am. J. Clin. Nutr

    (2006)
  • H.K. Berthold et al.

    JAMA

    (2006)
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