Chiara Righeschi

Essential Oils Loaded in Nanosystems: A Developing Strategy for a Successful Therapeutic Approach

Essential oils are complex blends of a variety of volatile molecules such as terpenoids, phenol-derived aromatic components, and aliphatic components having a strong interest in pharmaceutical, sanitary, cosmetic, agricultural, and food industries. Since the middle ages, essential oils have been widely used for bactericidal, virucidal, fungicidal, antiparasitical, insecticidal, and other medicinal properties such as analgesic, sedative, anti-inflammatory, spasmolytic, and locally anaesthetic remedies. In this review their nanoencapsulation in drug delivery systems has been proposed for their capability of decreasing volatility, improving the stability, water solubility, and efficacy of essential oil-based formulations, by maintenance of therapeutic efficacy. Two categories of nanocarriers can be proposed: polymeric nanoparticulate formulations, extensively studied with significant improvement of the essential oil antimicrobial activity, and lipid carriers, including liposomes, solid lipid nanoparticles, nanostructured lipid particles, and nano- and microemulsions. Furthermore, molecular complexes such as cyclodextrin inclusion complexes also represent a valid strategy to increase water solubility and stability and bioavailability and decrease volatility of essential oils.

Artemisinin and artemisinin plus curcumin liposomal formulations: Enhanced antimalarial efficacy against Plasmodium berghei-infected mice

The therapeutic efficacies of novel liposomal delivery systems based on artemisinin or artemisinin-based combination therapy with curcumin have been investigated and reported in this study. The developed liposomal formulations had proper characteristics as drug carriers for parental administration in terms of particle size, polydispersity, encapsulation efficacy and ζ-potential. Their physical and chemical stabilities were also evaluated. Furthermore, the in vivo antimalarial activity of artemisinin-based liposomal formulations was tested in Plasmodium berghei NK-65 infected mice, a suitable model for studying malaria because the infection presents structural, physiological and life cycle analogies with the human disease. Artemisinin, alone or in combination with curcumin, was encapsulated in conventional and PEGylated liposomes and its in vivo performance was assessed by comparison with the free drug. Mice were treated with artemisinin at the dosage of 50 mg/kg/days alone or plus curcumin as partner drug, administered at the dosage of 100 mg/kg/days. Artemisinin alone began to decrease parasitaemia levels only 7 days after the start of the treatment and it appeared to have a fluctuant trend in blood concentration which is reflected in the antimalarial effectiveness. By contrast, treatments with artemisinin-loaded conventional liposomes (A-CL), artemisinin-curcumin-loaded conventional liposomes (AC-CL), artemisinin-loaded PEGylated liposomes (A-PL), artemisinin-curcumin-loaded PEGylated liposomes (AC-PL) appeared to have an immediate antimalarial effect. Both nanoencapsulated artemisinin and artemisinin plus curcumin formulations cured all malaria-infected mice within the same post-inoculation period of time. Additionally, all formulations showed less variability in artemisinin plasma concentrations which suggested that A-CL, AC-CL, A-PL and AC-PL give a modified release of drug(s) and, as a consequence, a constant antimalarial effect during time. In particular, A-PL seems to give the most pronounced and statistically significant therapeutic effect in this murine model of malaria. The enhanced permanency in blood of A-PL suggests the use of these nanosystems as suitable passive targeted carriers for parasitic infections; this strong effect of formulation is added up to the mechanism of action of artemisinin which acts in the erythrocyte cycle stage of human host as a blood schizonticide.

Identification and quantification of constituents of Gardenia jasminoides Ellis (Zhizi) by HPLC-DAD–ESI–MS

A simple, rapid and specific HPLC method was carried out for the analysis of characteristic constituents in Gardenia jasminoides Ellis (Zhizi), namely iridoids, caffeoyl quinic acid derivatives and crocins. The separation was successfully obtained using a C(18) column by gradient elution with mixtures of methanol and water as mobile phases; detection wavelength was set at 240 nm for iridoid glycosides, 315 nm for quinic acid derivatives and 438 nm for crocins. The analytical method was validated and the quantification of active compounds, namely iridoids, was performed. Linearity, precision, repeatability, stability, accuracy, limit of detection (LOD) and limit of quantification (LOQ) were also reported. This assay was successfully applied for qualitative and quantitative analysis of five commercial samples of G. jasminoides Ellis.

Strategy to provide a useful solution to effective delivery of dihydroartemisinin: development, characterization and in vitro studies of liposomal formulations

Dihydroartemisinin is one of the most potent anticancer artemisinin-like compounds, able to induce cancer cell death by apoptotic pathways. Besides its effectiveness, it is a poorly water soluble drug with low bioavailability and low half-life (34-90 min), therefore, the development of new formulations of dihydroartemisinin to increase bioavailability is in great need. Conventional (P90G and cholesterol) and stealth liposomes (P90G; cholesterol and PE 18:0/18:0 PEG 2000) to deliver dihydroartemisinin to cancer cells were developed for the first time. Both developed formulations show physical characteristics as drug carrier for parental administration and good values of encapsulation efficiency (71% conventional liposomes and 69% stealth liposomes). Physical and chemical stabilities were evaluated under storage condition and in presence of albumin. Cellular uptake efficiency of liposomes was determined by flow cytometry. Higher internalization occurred in the conventional liposomes rather than in the stealth liposomes suggesting that hydrophilic steric barrier of PEG molecules can reduce cellular uptake. Flow cytometry analysis was also used as an alternative technique for rapid size determination of liposomes. Cytotoxicity studies in the MCF-7 cell line confirmed the absence of toxicity in blank formulations suggesting liposomes may be a suitable carrier for delivery of DHA avoiding the use of organic solvents. Cytotoxicity of DHA and of both liposomal formulations was evaluated in the same cell line, confirming a modified release of DHA from vesicles after cellular uptake.

Enhanced Efficacy of Artemisinin Loaded in Transferrin-Conjugated Liposomes versus Stealth Liposomes against HCT-8 Colon Cancer Cells.

Artemisinin (ART) is a unique sesquiterpene lactone isolated from Artemisia annua that is well known for antimalarial properties and was recently reported as a promising anticancer drug. The aim of our work was to develop a novel nanocarrier for enhanced ART delivery and activation in cancer tissues, because transferrin receptors are largely expressed in cancer cells and the iron content is higher than in normal cells. ART was loaded in transferrin‐conjugated liposomes (ART‐L‐Tf), and the performance was compared with ART loaded in stealth liposomes (ART‐L). All of the liposomes were fully characterized in terms of size, drug‐entrapment efficiency, transferrin coupling moieties, and stability. Both cell uptake and cytotoxicity studies of the developed nanocarriers were tested in the HCT‐8 cell line, selected among several cell lines because of transferrin receptor overexpression. The results confirmed the enhanced delivery of ART‐L‐Tf in comparison with ART‐L in the targeting of the HCT‐8 cell line and an improved cytotoxicity as a result of the presence of iron ions, which resulted in concomitant synergism derived from the increased expression of transferrin receptors on the surface of the tumor cells.