Vieri Piazzini

Improving on Nature: The Role of Nanomedicine in the Development of Clinical Natural Drugs

Natural products have been used as a major source of drugs for millennia, and about half of the pharmaceuticals in use today are derived from natural products. However, their efficacy can be limited because of their low hydrophilicity and intrinsic dissolution rate(s), or physical/chemical instability. In addition, they can present scarce absorption, poor pharmacokinetics and bioavailability, scarce biodistribution, first-pass metabolism, trivial penetration and accumulation in the organs of the body, or low targeting efficacy. Novel nanoformulations based on drug delivery systems, namely nanoparticles, micelles, and vesicles, offer significant promise in overcoming these limitations. Nowadays, nanomedicine is crucial in developing appropriate therapeutic treatments of essential drugs, specifically antitumor and antiparasistic agents (i.e., Taxol, vincristine, camptothecin, doxorubicin, artemisinin) and other emerging molecules with pleiotropic functions (i.e., resveratrol, curcumin, salvianolic acid B, honokiol). Additionally, the number of nanoformulations developed with flavonoids, in particular rutin, quercetin, silymarin, and green tea catechins, is constantly increasing, and a significant number of publications have appeared in the last decade pertaining to nanoformulations based on extracts and essential oils. Most of these studies report very promising nanoformulations with sustained release and improved bioavailability at much lower doses than conventional preparations, and in many cases, also a better safety profile.

Nanoemulsion for improving solubility and permeability of Vitex agnus-castus extract: formulation and in vitro evaluation using PAMPA and Caco-2 approaches

Abstract The purpose of this study was to develop new formulation for an improved oral delivery of Vitex agnus-castus (VAC) extract. After the optimization and validation of analytical method for quali-quantitative characterization of extract, nanoemulsion (NE) was selected as lipid-based nanocarrier. The composition of extract-loaded NE resulted in triacetin as oil phase, labrasol as surfactant, cremophor EL as co-surfactant and water. NE contains until 60 mg/mL of extract. It was characterized by DLS and TEM analyses and its droplets appear dark with an average diameter of 11.82 ± 0.125 nm and a polydispersity index (PdI) of 0.117 ± 0.019. The aqueous solubility of the extract was improved about 10 times: the extract is completely soluble in the NE at the concentration of 60 mg/mL, while its solubility in water results less than 6 mg. The passive intestinal permeation was tested by using parallel artificial membrane permeation assay (PAMPA) and the permeation across Caco-2 cells after preliminary cytotoxicity studies were also evaluated. NE shows a good solubilizing effect of the constituents of the extract, compared with aqueous solution. The total amount of constituents permeated from NE to acceptor compartment is greater than that permeated from saturated aqueous solution. Caco-2 test confirmed PAMPA results and they revealed that NE was successful in increasing the permeation of VAC extract. This formulation could improve oral bioavailability of extract due to enhanced solubility and permeability of phytocomplex.

Solid lipid nanoparticles for delivery of andrographolide across the blood-brain barrier: in vitro and in vivo evaluation

Andrographolide is a major diterpenoid of Andrographis paniculata and possesses several biological activities, including protection against oxidative stress mediated neurotoxicity, inflammation-mediated neurodegeneration, and cerebral ischemia. However, this molecule shows low bioavailability, poor water solubility, and high chemical and metabolic instability. The present study reports preparation of solid lipid nanoparticles (SLN) to deliver andrographolide (AG) into the brain. SLN were prepared using Compritol 888 ATO as solid lipid and Brij 78 as surfactant and applying emulsion/evaporation/solidifying method as preparative procedure. Nanoparticles have a spherical shape, small dimensions, and narrow size distribution. Encapsulation efficiency of AG-loaded SLN was found to be 92%. Nanoparticles showed excellent physical and chemical stability during storage at 4°C for one month. The lyophilized product was also stable at 25°C during the same period. SLN remained unchanged also in the presence of human serum albumin and plasma. In vitro release at pH 7.4 was also studied. The release of AG was prolonged and sustained when the compound was entrapped in SLN. The ability of SLN to cross the blood-brain barrier (BBB) was evaluated first in vitro by applying a permeation test with artificial membrane (parallel artificial membrane permeability assay, PAMPA) to predict passive and transcellular permeability through the BBB, and then by using hCMEC/D3 cells, a well-established in vitro BBB model. In vitro results proved that nanoparticles improved permeability of AG compared to free AG. Fluorescent nanoparticles were then prepared for in vivo tests in healthy rats. After intravenous administration, fluorescent SLN were detected in brain parenchyma outside the vascular bed, confirming their ability to overcome the BBB.

Albumin Nanoparticles for Brain Delivery: A Comparison of Chemical versus Thermal Methods and in vivo Behavior.

Human serum albumin nanoparticles (NPs) have gained considerable attention owing to their high loading capacity for various drugs and the fact that they are well tolerated. The aim of this work was to investigate two different methods to produce NPs without the use of organic solvents and to obtain useful drug‐delivery systems to cross the blood–brain barrier. NPs were obtained by coacervation, using both chemical and thermal cross‐linking processes. They were developed and optimized to target brain tissues after parenteral administration in healthy rats. Furthermore, their distribution, cellular uptake, and fate were investigated in vivo after intracerebral injection in healthy rats. The toxicity of the developed carriers was estimated by behavioral tests. All NPs were chemically and physically characterized by dynamic light scattering, transmission electron microscopy, and high‐performance liquid chromatography coupled with diode array and fluorimetric detectors. Their distribution and fate in the brain were evaluated by fluorescence microscopy. NPs were observed to be located in different brain tissues depending on the mode of injection, and did not induce an inflammatory response. Behavioral tests demonstrated no locomotor, explorative, or cognitive function impairment induced by the NPs.

Prediction of Permeation and Cellular Transport of Silybum marianum Extract Formulated in a Nanoemulsion by Using PAMPA and Caco-2 Cell Models.

The present study explores the potential of nanoemulsion, a lipid drug delivery system, to improve solubility and oral absorption of Silybum marianum extract. The optimized formulation contained 40 mg/mL of commercial extract (4 % w/w) and it was composed of 2.5 g labrasol (20 %) as the oil phase, 1.5 g cremophor EL as the surfactant, and 1 g labrafil as the cosurfactant (mixture surfactant/cosurfactant, 20 %).The system was characterized by dynamic light scattering, transmission electron microscopy, and HPLC-DAD analyses in order to evaluate size, homogeneity, morphology, and encapsulation efficiency. Physical and chemical stabilities were assessed during 40 days at 4 °C and 3 months at 25 °C. Stability in simulated gastric fluid followed by simulated intestinal conditions was also considered. In vitro permeation studies were performed to determine the suitability of the prepared nanoemulsion for oral delivery. Different models such as the parallel artificial membrane permeability assay and Caco-2 cell lines were applied.The nanoemulsion showed a good solubilizing effect of the extract, with a pronounced action also on its permeability, in respect to a saturated aqueous solution. The Caco-2 test confirmed the parallel artificial membrane permeability assay results and they revealed the suitability of the prepared nanoemulsion for oral delivery.

Andrographolide-loaded nanoparticles for brain delivery: Formulation, characterisation and in vitro permeability using hCMEC/D3 cell line

Graphical abstract Figure. No Caption available. HighlightsAndrographolide was loaded into albumin and poly‐ethylcyanoacrylate nanoparticles.Size, zeta‐potential, polydispersity and morphology were investigated.Blood brain barrier permeability was assessed using in vitro cell based model.UPLC‐MS/MS method was developed and validated according to EMA/FDA guidelines.Albumin nanoparticles improved permeation maintaining the integrity of cell layer. Abstract Andrographolide (AG) is a major diterpenoid of the Asian medicinal plant Andrographis paniculata which has shown exciting pharmacological potential for the treatment of inflammation‐related pathologies including neurodegenerative disorders. Conversely, the low bioavailability of AG still represents a limiting factor for its use. To overcome these limitations, AG was loaded into human serum albumin based nanoparticles (HSA NPs) and poly ethylcyanoacrylate nanoparticles (PECA NPs). HSA NPs were prepared by thermal (HSAT AG NPs) and chemical cross‐linking (HSAC AG NPs), while PECA AG NPs were produced by emulsion‐polymerization. NPs were characterized in terms of size, zeta (&zgr;)‐potential, polydispersity, and release studies of AG. In addition, the ability of free AG and AG‐loaded in PECA and HSAT NPs to cross the blood‐brain barrier (BBB) was assessed using an in vitro BBB model based on human cerebral microvascular endothelial cell line (hCMEC/D3). For BBB drug permeability assays, a quantitative UPLC‐MS/MS method for AG in Ringer HEPES buffer was developed and validated according to international regulatory guidelines for industry. Free AG did not permeate the BBB model, as also predicted by in silico studies. HSAT NPs improved by two‐fold the permeation of AG while maintaining the integrity of the cell layer, while PECA NPs temporarily disrupted BBB integrity.

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

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 ζ-potential result was negative. The maximum loading content of Salicis cortex extract resulted in 40 mg/mL. Furthermore, storage stability studies and an in vitro digestion assay were performed. The advantages offered by microemulsion were evaluated in vitro 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.

Lipid Nanocarriers for Oral Delivery of Serenoa repens CO2 Extract: A Study of Microemulsion and Self-Microemulsifying Drug Delivery Systems

The aim of this study was the development and characterization of lipid nanocarriers using food grade components for oral delivery of Serenoa repens CO2 extract, namely microemulsions (MEs) and self-microemulsifying drug delivery systems (SMEDDSs) to improve the oral absorption. A commercial blend (CB) containing 320 of S. repens CO2 extract plus the aqueous soluble extracts of nettle root and pineapple stem was formulated in two MEs and two SMEDDSs. The optimized ME loaded with the CB (CBM2) had a very low content of water (only 17.3%). The drug delivery systems were characterized by dynamic light scattering, transmission electron microscopy, and high-performance liquid chromatography (HPLC) with a diode-array detector analyses in order to evaluate the size, the homogeneity, the morphology, and the encapsulation efficiency. β-carotene was selected as marker for the quantitative HPLC analysis. Additionally, physical and chemical stabilities were acceptable during 3 wk at 4 °C. Stability of these nanocarriers in simulated stomach and intestinal conditions was proved. Finally, the improvement of oral absorption of S. repens was studied in vitro using parallel artificial membrane permeability assay. An enhancement of oral permeation was found in both CBM2 and CBS2 nanoformulations comparing with the CB and S. repens CO2 extract. The best performance was obtained by the CBM2 nanoformulation (~ 17%) predicting a 30 - 70% passive oral human absorption in vivo.

Stealth and Cationic Nanoliposomes as Drug Delivery Systems to Increase Andrographolide BBB Permeability

(1) Background: Andrographolide (AG) is a natural compound effective for the treatment of inflammation-mediated neurodegenerative disorders. The aim of this investigation was the preparation of liposomes to enhance the penetration into the brain of AG, by modifying the surface of the liposomes by adding Tween 80 (LPs-AG) alone or in combination with Didecyldimethylammonium bromide (DDAB) (CLPs-AG). (2) Methods: LPs-AG and CLPs-AG were physically and chemically characterized. The ability of liposomes to increase the permeability of AG was evaluated by artificial membranes (PAMPA) and hCMEC/D3 cells. (3) Results: Based on obtained results in terms of size, homogeneity, ζ-potential and EE%. both liposomes are suitable for parenteral administration. The systems showed excellent stability during a month of storage as suspensions or freeze-dried products. Glucose resulted the best cryoprotectant agent. PAMPA and hCMEC/D3 transport studies revealed that LPs-AG and CLPs-AG increased the permeability of AG, about an order of magnitude, compared to free AG without alterations in cell viability. The caveolae-mediated endocytosis resulted the main mechanism of up-take for both formulations. The presence of positive charge increased the cellular internalization of nanoparticles. (4) Conclusions: This study shows that developed liposomes might be ideal candidates for brain delivery of AG.

Topical formulations of delta-aminolevulinic acid for the treatment of actinic keratosis: Characterization and efficacy evaluation

Abstract Actinic keratosis (AK) is a pre‐cancerous disease, with worldwide increasing incidence, which consists in squamous cutaneous lesion caused by excessive exposure to ultraviolet radiation. An established treatment option is photodynamic therapy (PDT), based on light, oxygen and a photosensitizer. The most widely used is 5‐aminolevulinic acid (ALA) which however, being a hydrophilic molecule, has difficultly penetrating the skin to achieve the desired therapeutic effect. To solve this limit, the present study provides for the development of three galenic gel formulations (Natrosol, Sepigel and Carbopol) containing 10% w/w of ALA for the treatment of AK with PDT and their comparison with a lipophilic cream used in the Hospital. The aim of this study is to offer an appealing topical treatment that improves patients’ observance and compliance. Formulations were characterized in terms of chemical, physical and microbiological stability, viscosity and pH. An HPLC‐DAD analytical method was also developed and validated. Sepigel gel resulted the best gel formulation in terms of technological characteristics and stability. A comparative study between this gel and the lipophilic cream was assessed, by evaluating the therapeutic efficacy and the compliance of the patients. Graphical abstract Figure. No caption available.