Curcumin and quercetin co-encapsulated in nanoemulsions for nasal administration: A promising therapeutic and prophylactic treatment for viral respiratory infections.

One of the most frequent causes of respiratory infections are viruses. Viruses reaching the airways can be absorbed by the human body through the respiratory mucosa and mainly infect lung cells. Several viral infections are not yet curable, such as coronavirus-2 (SARS-CoV-2). Furthermore, the side effect of synthetic antiviral drugs and reduced efficacy against resistant variants have reinforced the search for alternative and effective treatment options, such as plant-derived antiviral molecules. Curcumin (CUR) and quercetin (QUE) are two natural compounds that have been widely studied for their health benefits, such as antiviral and anti-inflammatory activity. However, poor oral bioavailability limits the clinical applications of these natural compounds. In this work, nanoemulsions (NE) co-encapsulating CUR and QUE designed for nasal administration were developed as promising prophylactic and therapeutic treatments for viral respiratory infections. The NEs were prepared by high-pressure homogenization combined with the phase inversion temperature technique and evaluated for their physical and chemical characteristics. In vitro assays were performed to evaluate the nanoemulsion retention into the porcine nasal mucosa. In addition, the CUR and QUE-loaded NE antiviral activity was tested against a murine ß-COV, namely MHV-3. The results evidenced that CUR and QUE loaded NE had a particle size of 400 nm and retention in the porcine nasal mucosa. The antiviral activity of the NEs showed a percentage of inhibition of around 99 %, indicating that the developed NEs has interesting properties as a therapeutic and prophylactic treatment against viral respiratory infections.

Toward a Platform for the Treatment of Burns: An Assessment of Nanoemulsions vs. Nanostructured Lipid Carriers Loaded with Curcumin.

Curcumin is a highly promising substance for treating burns, owing to its anti-inflammatory, antioxidant, antimicrobial, and wound-healing properties. However, its therapeutic use is restricted due to its hydrophobic nature and low bioavailability. This study was conducted to address these limitations; it developed and tested two types of lipid nanocarriers, namely nanoemulsions (NE-CUR) and nanostructured lipid carriers (NLC-CUR) loaded with curcumin, and aimed to identify the most suitable nanocarrier for skin burn treatment. The study evaluated various parameters, including physicochemical characteristics, stability, encapsulation efficiency, release, skin permeation, retention, cell viability, and antimicrobial activity. The results showed that both nanocarriers showed adequate size (~200 nm), polydispersity index (~0.25), and zeta potential (~>-20 mV). They also showed good encapsulation efficiency (>90%) and remained stable for 120 days at different temperatures. In the release test, NE-CUR and NCL-CUR released 57.14% and 51.64% of curcumin, respectively, in 72 h. NE-CUR demonstrated better cutaneous permeation/retention in intact or scalded skin epidermis and dermis than NLC-CUR. The cell viability test showed no toxicity after treatment with NE-CUR and NLC-CUR up to 125 µg/mL. Regarding microbial activity assays, free curcumin has activity against P. aeruginosa, reducing bacterial growth by 75% in 3 h. NE-CUR inhibited bacterial growth by 65% after 24 h, and the association with gentamicin had favorable results, while NLC-CUR showed a lower inhibition. The results demonstrated that NE-CUR is probably the most promising nanocarrier for treating burns.

Curcumin and Quercetin-Loaded Lipid Nanocarriers: Development of Omega-3 Mucoadhesive Nanoemulsions for Intranasal Administration.

Curcumin (CUR) and quercetin (QU) are potential compounds for treatment of brain diseases such as neurodegenerative diseases (ND) because of their anti-inflammatory and antioxidant properties. However, low water solubility and poor bioavailability hinder their clinical use. In this context, nanotechnology arises as a strategy to overcome biopharmaceutical issues. In this work, we develop, characterize, compare, and optimize three different omega-3 (ω-3) fatty acids nanoemulsions (NEs) loaded with CUR and QU (negative, cationic, gelling) prepared by two different methods for administration by intranasal route (IN). The results showed that formulations prepared with the two proposed methods exhibited good stability and were able to incorporate a similar amount of CUR and QU. On the other side, differences in size, zeta potential, in vitro release kinetics, and permeation/retention test were observed. Considering the two preparation methods tested, high-pressure homogenization (HPH) shows advantages, and the CQ NE- obtained demonstrated potential for sustained release. Toxicity studies demonstrated that the formulations were not toxic for Caenorhabditis elegans. The developed ω-3 fatty acid NEs have shown a range of interesting properties for the treatment of brain diseases, since they have the potential to increase the nose-to-brain permeation of CUR and QU, enabling enhanced treatments efficiency.

Nanoemulsion Improves the Neuroprotective Effects of Curcumin in an Experimental Model of Parkinson's Disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by motor dysfunction. Recent studies have shown that curcumin (CUR) has neuroprotective effects in PD experimental models. However, its efficacy is limited due to low water solubility, bioavailability, and access to the central nervous system. In this study, we compared the effects of new curcumin-loaded nanoemulsions (NC) and free CUR in an experimental model of PD. Adult Swiss mice received NC or CUR (25 and 50 mg/kg) or vehicle orally for 30 days. Starting on the eighth day, they were administered rotenone (1 mg/kg) intraperitoneally until the 30th day. At the end of the treatment, motor assessment was evaluated by open field, pole test, and beam walking tests. Oxidative stress markers and mitochondrial complex I activity were measured in the brain tissue. Both NC and CUR treatment significantly improved motor impairment, reduced lipoperoxidation, modified antioxidant defenses, and prevented inhibition of complex I. However, NC was more effective in preventing motor impairment and inhibition of complex I when compared to CUR in the free form. In conclusion, our results suggest that NC effectively enhances the neuroprotective potential of CUR and is a promising nanomedical application for PD.