Enhanced Solubility and Permeability of Salicis cortex Extract by Formulating as a Microemulsion

Abstract

A microemulsion system was developed and investigated as a novel oral formulation to increase the solubility and absorption of Salicis cortex extract. This extract possesses many pharmacological activities, in particular, it is beneficial for back pain and osteoarthritic and rheumatic complaints. In this work, after qualitative and quantitative characterization of the extract and the validation of an HPLC/diode array detector analytical method, solubility studies were performed to choose the best components for microemulsion formulation. The optimized microemulsion consisted of 2.5 g of triacetin, as the oil phase, 2.5 g of Tween 20 as the surfactant, 2.5 g of labrasol as the cosurfactant, and 5 g of water. The microemulsion was visually checked, characterized by light scattering techniques and morphological observations. The developed formulation appeared transparent, the droplet size was around 40 nm, and the -potential result was negative. The maximum loading content of Salicis cortex extract resulted in 40 mg/mL. Furthermore, storage stability studies and an digestion assay were performed. The advantages offered by microemulsion were evaluated using artificial membranes and cells, i.e., parallel artificial membrane permeability assay and a Caco-2 model. Both studies proved that the microemulsion was successful in enhancing the permeation of extract compounds, so it could be useful to ameliorate the bioefficacy of Salicis cortex.

Formulation of Nanomicelles to Improve the Solubility and the Oral Absorption of Silymarin

“…The Parallel Artificial Membrane Permeability Assay (PAMPA) permits the fast in vitro determination of the ability of a compound to permeate artificial membranes by passive diffusion and therefore to estimate the gastrointestinal absorption after oral administration [51]. PAMPA gives information not only on the permeability of single molecules, but also on the behavior of the extracts, and recently the test was introduced to study formulated drugs [24,26,52,53,54,55]. In this work, PAMPA was used to evaluate to effect of nanomicelles on SLM permeability.…”

“…After the application of the artificial membrane, 0.25 mL of SLM-PNM, SLM-MNM and SLM solution was added to each well of the donor compartment, and 0.25 mL of 5% DMSO solution in PBS was added to each well acceptor compartment. Then, after placing the donor compartment into the acceptor compartment, the system was transferred into a sealed container and incubated at room temperature for 2 h. After the incubation, SLM concentration in the donor and acceptor compartment was determined by HPLC [24,26,52,53,55,56]. The effective permeability ( P e , cm/s) was estimated with the following equation, Pe=−ln[1−CAtCeq]A(1VD+1VA)t where A is the active surface area, V D and V A the well volume of the donor and acceptor plate, respectively, t the incubation time (s), C At and C Dt the concentration of SLM in the acceptor and donor plate at time t , respectively.…”

Nanostructured Lipid Carriers as Promising Delivery Systems for Plant Extracts: The Case of Silymarin

“…The permeation of SLM alone and SLM-NLCs through artificial membranes was determined using the protocol optimized in our previous studies [10,15,16,34]. The 96-well microtiter PVDF filter plate was impregnated with 10 µL of a lecithin (1% w/v) and cholesterol (0.8% w/v) in 1,7-octadiene solution.…”

“…Permeation studies were performed using a cell-based model in order to complete in vitro characterization of NLCs and understand oral absorption mechanisms. For this aim, Caco-2 cells are considered the most predictive in vitro model to estimate not only passive intestinal diffusion, as previously described for PAMPA, but also active transport processes, paracellular permeability and active efflux [10,15,16].…”

“…Furthermore, plant extracts present critical issues due to the wide variety of the compounds contained therein. There are numerous examples of application of the drug delivery systems in this field related to isolated products or herbal extracts [8][9][10][11][12][13]. In particular, oral absorption of lipophilic extract can be significantly improved using lipid-based non-particulate drug delivery systems, which avoid the dissolution step.…”