Solubility, Solution Thermodynamics, and Preferential Solvation of Amygdalin in Ethanol + Water Solvent Mixtures.

Abdelkarim Aydi,Kaouther Ghachem,Mohammad Alnaief,Daniel Delgado,Lioua Kolsi,Abdulaal Al-Khazaal,Cherifa Ayadi

doi:10.3390/ph13110395

Abstract

The equilibrium solubility of amygdalin in [ethanol (1) + water (2)] mixtures at 293.15 K to 328.15 K was reported. The thermodynamic properties (standard enthalpy ΔsolnH°, standard entropy ΔsolnS°, and standard Gibbs energy of solution ΔsolnG°) were computed using the generated solubility data via van’t Hoff and Gibbs equations. The dissolution process of amygdalin is endothermic and the driving mechanism in all mixtures is entropy. Maximal solubility was achieved in 0.4 mole fraction of ethanol at 328.15 K and the minimal one in neat ethanol at 293.15 K. Van’t Hoff, Jouyban–Acree–van’t Hoff, and Buchowski–Ksiazczak models were used to simulate the obtained solubility data. The calculated solubilities deviate reasonably from experimental data. Preferential solvation parameters of amygdalin in mixture solvents were analyzed using the inverse Kirkwood–Buff integrals (IKBI) method. Amygdalin is preferentially solvated by water in ethanol-rich mixtures, whereas in water-rich mixtures, there is no clear evidence that determines which of water or ethanol solvents would be most likely to solvate the molecule.

Highlights

Amygdalin (Figure 1) is a naturally occurring cyanogenic diglycoside with a molecular formula of C20H27NO11 and a molecular mass of 457.4 g mol−1
The use of amygdalin can lead to the release of toxic hydrogen cyanide (HCN) through the action of emulsin enzyme from the human intestinal microflora [3]
Highly purified amygdalin used in therapeutic dosage levels has antioxidant, anti-fibrosis [7], anti-inflammatory, analgesic [8,9], anti-atherosclerosis [10,11,12], anti-cardiac

Summary

Introduction

Amygdalin (Figure 1) is a naturally occurring cyanogenic diglycoside with a molecular formula of C20H27NO11 and a molecular mass of 457.4 g mol−1. It is a major bioactive component present mostly in kernels and seeds of “Rosaceae” plants such as peaches, apples, cherries, and more [1,2]. 0.6F0or the2.a2b0ove-me2n.5t8ioned r3e.a1s7ons, th3e.9so4lubilit4y.1a4nd solu4t.i8o1n therm5.o5d5ynami6c.s3o0f amyg7d.8a9lin in pmui00rxe..t78uTa00rhnedussas,ort11elhv..t50eeh30ngetommaloissxtot11ufv..82rete81hrssisaatrsietleuqda21uny..i13td46ewmeesroseset(n1ut21)is..a57telo20daensxodtlevmnedu21n..st87tths36byeesdtdeamettaes32br..fam20os52rientohendes.tehT32peh..74rese74obvliiunobauirslyipt42ywu..16ora22ptfeoarsmaesnyd[g522d..e449at–53hl2ian7n].ionl sev0e.9ra0l etha0n.o7l1(1) + w0a.8te3r (2) m0ix.9tu1res ove1r.1a2temper1a.1tu5re rang1e.2o7f 298.1015.3t5o 328.151.K57, (2) to s1t.u7d0y the effe1c.0t0of solv0e.5n1t comp0o.s5i6tion on0t.h6e1solubi0li.t6y5and so0l.u6t9ion the0rm.77odynam0i.9cs of amy0g.9d4alin in1a.q0u3eous ethana oAlvmeriaxgteurreesla, t(i3v)etounccaelrctualinattey tihnemaoplpeafrreancttiothnesromluobdilyitnyaims uic(xf3u)n=ct0i.o0n25s.obfSstoalnudtaiordn uinnctheretaiinnvtyesitnigated pressure u(p) = 0.001 MPa. c x1 is the mole fraction of ethanol (1) in the {ethanol (1) + water (2)}. Some models were used to predict the solubility of amygdalin in ethanol–water mixtures at different temperatures

Results and Discussion

Computational Validation

Enthalpy–Entropy Compensation

Preferential Solvation