IJTech International Journal of Technology

Mangosteen (Garcinia mangostana L.) is a fruit that is rich in xanthones, utilized as health supplements or additives in food products due to their high antioxidant activities. Choline chloride (ChCl)-based deep eutectic solvents (DESs) with polyalcohols (ethylene glycol, glycerol, propanediols, and butanediols) as hydrogen bonding donors (HBDs) were used to extract the xanthones from the pericarp of mangosteen. DESs with 1,2-propanediol, 1,3-propanediol, and 1,2-butanediol as HBDs (ChCl to HBD mole ratio of 1:3) afforded the highest extraction yields (2.40-2.63%) of α-mangostin, the most abundant component that represents xanthones. These DESs have intermediate Nile Red polar parameter values similar to that of ethanol and provide extraction yields with a quadratic dependence on the polar parameter. Polarity and viscosity, the important physicochemical properties to consider in the selection of DES as an extraction solvent, could be adjusted based on the consideration of the molecular structure of the polyalcohols. The following factors qualifies the ChCl-1,2-propanediol DES as a designer solvent for green extraction: It is selected from a set of DESs having a homologous class of HBDs to deliver the highest α-mangostin extraction yield, its extract composition similar to that obtained using ethanol, it has low or negligible vapor pressure, both of its components are generally recognized as safe chemicals so that direct utilization of a DES extract is possible, and this DES is used for utilization of agricultural waste products as the resource of bioactive compounds.

This study was conducted to determine the effectiveness of Natural Deep Eutectic Solvent (NADES), consisting of choline chloride and a hydrogen bonding donor (HBD) compound, in terms of carbon dioxide absorption. Solubility of carbon dioxide in NADES was found to be influenced HBD compound used and choline chloride to HBD ratio, carbon dioxide pressure, and contact time. HBD and choline/HBD ratios used were 1,2-propanediol (1:2), glycerol (1:2), and malic acid (1:1). The carbon dioxide absorption measurement was conducted using an apparatus that utilizes the volumetric method. Absorption curves were obtained up to pressures of 30 bar, showing a linear relationship between the amount absorbed and the final pressure of carbon dioxide. The choline and 1,2-propanediol eutectic mixture absorbs the highest amount of carbon dioxide, approaching 0.1 mole-fraction at 3.0 MPa and 50°C. We found that NADES ability to absorb carbon dioxide correlates with its polarity as tested using Nile Red as a solvatochromic probe.

Chitosan-alginate microparticles loaded with hydrophobic mangostins present in the mangosteen rind extract have been formulated and optimized for colon-targeted bioactive drug delivery systems. The chitosan–mangostin microparticles were prepared using the ionotropic gelation method with sodium tripolyphosphate as the cross-linking agent of chitosan. The chitosan–mangostin microparticles were then encapsulated in alginate with calcium chloride as the linking agent. The mangostin release profile was optimized using the Box–Behnken design for response surface methodology with three independent variables: (A) chitosan–mangostin microparticle size, (B) alginate:chitosan mass ratio, and (C) concentration of calcium chloride. The following representative equation was obtained: percent cumulative release of mangostins (10 h) = 59.51 − 5.16A + 20.00B − 1.27C − 1.70AB − 5.43AC − 5.04BC + 0.0579A² + 10.25B² + 1.10C². Cumulative release of 97% was obtained under the following optimum condition for microparticle preparation: chitosan–mangosteen particle size < 100 µm, alginate:chitosan mass ratio of 0.5, and calcium chloride concentration of 4% w/v. The alginate to chitosan mass ratio is the statistically significant variable in the optimization of sequential release profile of mangostins in simulated gastrointestinal fluids. Furthermore, a sufficient amount of alginate is necessary to modify the chitosan microparticles and to achieve a complete release of mangostins. The results of this work indicate that the complete release of mangostins to the colon area can be achieved using the chitosan–alginate microparticles as the bioactive delivery system.