Recently, essential oil from Amomum kravanh (AMO) was reported to exert anti-oral cancer effects. Although it was more effective after being loaded into nanoemulsions, AMO without an Ostwald ripening inhibitor was unable to form stable nanoemulsions because of the Ostwald ripening phenomenon. In this study, we examined the influence of Ostwald ripening inhibitors, such as fixed oils and polyethylene glycol 4000 (PEG 4000), on nanoemulsion properties prepared by a phase inversion temperature method. Several fixed oils, including virgin coconut oil (VCO), palm oil (PMO), olive oil (OLO), and PEG 4000, were evaluated, and their Ostwald ripening inhibitory effects were compared. The results suggest that the type and ratio of AMO:fixed oils influence the formation and characteristics of nanoemulsions. PEG 4000 was unable to produce nanoemulsions; however, stable nanoemulsions with small droplet sizes were observed in preparations containing OLO and VCO at an AMO:fixed oil ratio of 80:20, which may be the result of specific molecular interactions among the components. Using an MTT assay, we demonstrated that the AMO:OLO (80:20) nanoemulsion produced the most significant cytotoxic effect on oral cancer cells with a percentage of 99.68 ± 0.56%. Furthermore, the AMO:OLO 80:20 nanoemulsion inhibits metastasis and induces oral cancer cell death through the intrinsic apoptosis pathway. In conclusion, AMO nanoemulsion with anti-oral cancer activity was successfully produced by varying the amount and type of fixed oils. In the future, this discovery may lead to the development of stable nanoemulsions employing additional volatile oils.

Quercetin (QCT), a natural flavonoid, is of research interest owing to its pharmacological properties. However, its pharmacokinetic limitations could hinder its widespread therapeutic use. Nanocarriers, especially solid lipid nanoparticles (SLNs), might overcome this constraint. This study aimed to investigate QCT-loaded SLNs prepared via a new approach using a volatile oil. The phase-inversion temperature method was used to incorporate rosemary oil (RMO) into SLNs prepared using solid lipids possessing different chemical structures. Among the solid lipids used in the formulations, trilaurin (TLR) exhibited the smallest particle size and good stability after a temperature cycling test. SLNs prepared with a ratio of RMO to TLR of 1:3 could load QCT with an entrapment efficiency of >60% and drug loading of ~2% w/w. The smallest particle size was achieved using the polyoxyethylene-hydrogenated castor oil RH40, and the particle size depended on the concentration. The drug-release profile of QCT_TLR exhibited prolonged biphasic release for >24 h. QCT_TLR was a safe formulation, as indicated by a cell viability percentage of >75% at <2% v/v. In a computer simulation, the system with RMO enabled smaller sized SLNs than those without RMO. This new discovery shows great promise for producing SLNs via the phase-inversion temperature method with incorporation of volatile oil, particularly for delivering compounds with limited water solubility.

Kaempferia parviflora, a medicinal herb, treats hypertension and promotes longevity with good health and well-being. Its bioactive component is poorly soluble in water, resulting in poor absorption. This study aimed to enhance the bioavailability of K. parviflora dichloromethane extract (KPD) using a self-nanoemulsifying drug delivery system (SNEDDS). KPD was dissolved in diethylene glycol monoethyl polyoxyl-35 castor oil and caprylic/capric glyceride, and clear yellow SNEDDS solution was obtained. The methoxyflavone markers were used for content and dissolution analysis. Solid SNEDDS was prepared by stepwise mixing of KPD using a mortar and pestle (1:1 ratio) with five solid carriers: Aerosil® 200, Florite^® RE, Neusilin^® US2 (NEUS), Fujicalin^®, and Neusilin^® UFL2. The USP apparatus II with simulated gastric fluid USP (SGF without pepsin, pH 1.2) was used in order to perform the in vitro dissolution. The methoxyflavones dissolution at 60 min from KPD, SEDDS, and SNEDDS/NEUS were approximately 16%, 92%, and 73%, respectively. The pharmacokinetic profiles of methoxyflavones for oral administration were studied using Wistar rats; the areas under the curve of SNEDDS/NEUS (1.77-fold) and SNEDDS (5.38-fold) were significantly higher than that of KPD. The developed formulations showed good stability after storage for 6 months under accelerated and normal conditions.

Ternary solid solutions composed of nifedipine (NDP), amino methacrylate copolymer (AMCP), and polysorbate (PS) 20, 60, or 65 were prepared using a solvent evaporation method. The dissolution profiles of NDP were used to study the effect of the addition of polysorbate based on hydrophilic properties. A solid solution of NDP and AMCP was recently developed; however, the dissolution of NDP was <70%. In the present study, polysorbate was added to improve the dissolution of the drug by altering its hydrophilicity. The suitable formulation contained NDP and AMCP at a ratio of 1:4 and polysorbate at a concentration of 0.1%, 0.3%, or 0.6%. Differential scanning calorimetry and powder X-ray diffraction were used to examine the solid solutions. No peak representing crystalline NDP was observed in any solid solution samples, suggesting that the drug was molecularly dispersed in AMCP. The NDP dissolution from NDP powder and solid solution without PS were 16.82% and 58.19%, respectively. The highest dissolution of NDP of approximately 95.25% was noted at 120 min for the formulation containing 0.6% PS20. Linear correlations were observed between the surface free energy and percentages of dissolved NDP (R² = 0.7115–0.9315). Cellular uptake across Caco-2 was selected to determine the drug permeability. The percentages of cellular uptake from the NDP powder, solid solution without and with PS20 were 0.25%, 3.60%, and 7.27%, respectively.

Among natural sources, guava leaf oil (GLO) has emerged as a potential anticancer agent. However, its limited water solubility poses a significant challenge for its use. Oil-in-water nanoemulsions are used to address the limitation of water solubility of GLO prior to its incorporation into orodipersible films. Nanoemulsions containing GLO:virgin coconut oil (VCO) at a ratio of 50:50 to 70:30 presented a small droplet size of approximately 50 nm and a relatively low zeta potential. GLO:VCO at a ratio of 70:30 was selected for incorporation into sodium alginate film at various concentrations ranging from 1% to 30% w/w. Tensile strength and elongation at break relied on the concentration of nanoemulsions as well as the internal structure of films. Fourier transform infrared spectroscopy revealed that GLO was compatible with sodium alginate. Film containing 2% w/w of nanoemulsions (2G_ODF) exhibited effective in vitro antioral cancer activity, with an IC₅₀ of 62.49 ± 6.22 mg/mL; furthermore, its anticancer activity showed no significant difference after storage at 25 °C for 1 year. Moreover, 2G_ODF at IC₆₀ arrested colony formation and cell invasion. There is also evidence that cell death occurred via apoptosis, as indicated by nuclear fragmentation and positive Annexin-V staining. These findings highlight the potential of orodispersible films containing GLO nanoemulsions as a prospective oral anticancer agent.