Supercritical CO2 extraction of α-bisabolol from different parts of candeia wood (Eremanthus erythropappus)

Microemulsions strongly promoted the activity of α-bisabolol against different Leishmania species and its skin permeation

This study aimed to develop microemulsions (MEs) containing α-bisabolol for the topical treatment of cutaneous leishmaniasis (CL). Initially, pseudoternary phase diagrams were developed using α-bisabolol as the oil phase, Eumulgin® CO 40 as the surfactant, Polymol® HE as the co-surfactant, and distilled water as the aqueous phase. Two transparent liquid systems (TLS) containing 5% of α-bisabolol were selected and characterized (F5E25 and F5EP25). Next, skin permeation and retention assays were performed using Franz cells. The interaction of the formulation with the stratum corneum (SC) was evaluated using the FTIR technique. The cytotoxicity was evaluated in murine peritoneal macrophages. Finally, the antileishmanial activity of microemulsions was determined in promastigotes and amastigotes of L. amazonensis (strain MHOM/BR/77/LTB 0016). As a result, the selected formulations showed isotropy, nanometric size (below 25 nm), Newtonian behavior and pH ranging from 6.5 to 6.9. The MEs achieved a 2.5-fold increase in the flux and skin-permeated amount of α-bisabolol. ATR-FTIR results showed that microemulsions promoted fluidization and extraction of lipids and proteins of the stratum corneum, increasing the diffusion coefficient and partition coefficient of the drug in the skin. Additionally, F5E25 and F5EP25 showed higher activity against promastigotes (IC50 13.27 and 18.29, respectively) compared to unencapsulated α-bisabolol (IC50 53.8). Furthermore, F5E25 and F5EP25 also showed antileishmanial activity against intracellular amastigotes of L. amazonensis, with IC50 50 times lower than free α-bisabolol and high selectivity index (up to 15). Therefore, the systems obtained are favorable to topical administration, with significant antileishmanial activity against L. amazonensis promastigotes and amastigotes, being a promising system for future in vivo trials.

Dewatering of Juglans mandshurica Wood Using Supercritical Carbon Dioxide

Supercritical carbon dioxide (ScCO2), known for such features as good solubility and mass transfer properties, can be an efficient drying medium for various materials, such as wood, by filling the pore space and dissolving water in the cell cavity without altering the microstructure. In this study, two specimens of Juglans mandshurica wood with a length of 30 mm and 140 mm were subjected to ScCO2 dewatering under four different pressure and temperature conditions. The results showed that the drying rate is mainly influenced by pressure and temperature, with pressure having the more significant effect. Moreover, the efficiency of dewatering was not dependent on the sample length under the same conditions. The moisture content (MC) was the same along the longitudinal direction throughout both the surfaces and core of the wood. While there were no significant differences in dewatering rate between tangential and radial directions and lengths of samples, significant MC gradient differences were noted along wood in radial and tangential directions. During ScCO2 dewatering, the dominant water transfer occurred from the middle towards the end surfaces along the wood's longitudinal directions. Furthermore, ScCO2 dewatering did not result in any shrinkage or significant drying stress, but it did cause some swelling in Juglans mandshurica wood.

Green and Efficient Processing of Wood with Supercritical CO2: A Review

Wood processing is a crucial step of wood utilization, but the adding of environmentally hazardous feedstocks and the use of unreasonable technology allow it to harm the environment and human health. Supercritical CO2 (scCO2) is a non-toxic, odorless, and safe solvent, which is widely used in studies and industrial production, but there is no review summarizing wood processing with scCO2. The unique structure and chemical properties of wood combined with scCO2 technology produce positive results. In this paper, wood processing with scCO2 is summarized, including wood impregnation, wood drying, wood thermochemical conversion, and wood extraction. The green and efficient characteristics of wood processing with scCO2 are explained in detail for researchers, engineers, and investors to provide a clean wood processing method. Further study is needed to reduce its energy consumption and commercialize it eventually.