Partitioning, solubility and solubilization of limonene into water or short‐chain phosphatidylcholine solutions

Abstract

Using headspace solid‐phase microextraction (HS–SPME), equilibrium distributions could be determined for hydrophobic solutes in closed systems containing vapor and aqueous solution, either in the absence or presence of two short‐chain phospholipids, dihexanoyl‐phosphatidylcholine (diC6PC) and diheptanoyl‐phosphatidylcholine (diC7PC). Without phospholipid, HS–SPME with short extraction times was used to measure water–vapor partition coefficients Kvw for d‐limonene at five temperatures within 15–40°C, with results in good agreement with existing literature. The temperature dependence of Kvw yielded the enthalpy of volatilization ΔvoltrueH¯= 34.5 kJ/mol for limonene. At 25°C, solubility values for d‐limonene, 1‐octanol, and n‐decane were obtained using similar measurements above aqueous solutions of various solute concentrations. Short‐time HS–SPME extraction of limonene in closed vials containing diC6PC or diC7PC micelles was also used to evaluate distributions of solute between vapor, aqueous dissolution, and micelles, for various surfactant concentrations at 15–40°C. Resulting vapor phase concentrations were analyzed using a mass balance and measured Kvw values, to obtain micelle–water partition coefficients Kmw and critical micelle concentrations. Kmw in diC6PC solutions (1–2 mM−1) weakly increased with temperature, but decreased significantly with increased temperature for diC7PC micelles (2–4 mM−1). Solubilization in short‐chain PC micelles has previously received little attention, and our results show that the extent of partitioning into these diacyl (i.e., two‐tailed) lipids is comparable to that for single‐tailed anionic or nonionic surfactants.

The Formation of Self-Assembled Nanoparticles Loaded with Doxorubicin and d-Limonene for Cancer Therapy

“…Recent studies have shown that d -limonene possesses anti-oxidant activity and protects lymphocytes from oxidative stress induced by hydrogen peroxide. , Moreover, numerous reports have shown that d -limonene has anticancer activity on various types of cancer as it can trigger apoptosis and regulate the cell cycle. , In addition, a study conducted by Rehman et al showed that d -limonene can be used as a protective agent against the nephrotoxic effect of DOX . However, d -limonene suffered from low water solubility due to its hydrophobic nature, which hampered its use and efficacy . Therefore, it is necessary to develop a suitable delivery system to improve the solubility, bioavailability, and encapsulation of d -limonene and DOX.…”

“… 30 However, d -limonene suffered from low water solubility due to its hydrophobic nature, which hampered its use and efficacy. 31 Therefore, it is necessary to develop a suitable delivery system to improve the solubility, bioavailability, and encapsulation of d -limonene and DOX. Herein, we aim to prepare three different self-assembled nanomaterials (nanoemulsion, niosomes, and polylactide (PDLLA) nanoparticles) and study their capability to encapsulate d -limonene and DOX.…”

Water Plays Multifunctional Roles in the Intervening Formation of Secondary Organic Aerosols in Ozonolysis of Limonene: A Valence Photoelectron Spectroscopy and Density Functional Theory Study

“…Because EtOH is highly volatile, EtOH evaporates more rapidly than water during the flight of limonene/EtOH/water aerosols to the photoionization region. On the contrary, because water exhibits an evaporation barrier and limonene exhibits a very low solubility in water (on the order of ∼10 –4 M), , water does not evaporate completely, thus retaining an aqueous interface for the remaining aqueous aerosols, allowing limonene to be adsorbed at the air–water interface. Previous studies have corroborated that volatile organic compounds (VOCs) tend to be adsorbed on or near the air–water interface, and the aqueous interface may affect the electronic properties and chemical activities of VOCs as a result of their interfacial solvation structure and hydrogen bond network. ,,, As limonene molecules become increasingly enriched at the surface of limonene/water mixed aerosols, they may encounter and thus be photoionized by VUV photons more readily, thereby increasing the TEYs of limonene aerosols.…”