Novel strategy for improving the bioavailability of curcumin based on a new membrane transport mechanism that directly involves solid particles

Anti-Viral Potential and Modulation of Nrf2 by Curcumin: Pharmacological Implications

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential transcription factor that maintains the cell's redox balance state and reduces inflammation in different adverse stresses. Under the oxidative stress, Nrf2 is separated from Kelch-like ECH-associated protein 1 (Keap1), which is a key sensor of oxidative stress, translocated to the nucleus, interacts with the antioxidant response element (ARE) in the target gene, and then activates the transcriptional pathway to ameliorate the cellular redox condition. Curcumin is a yellow polyphenolic curcuminoid from Curcuma longa (turmeric) that has revealed a broad spectrum of bioactivities, including antioxidant, anti-inflammatory, anti-tumor, and anti-viral activities. Curcumin significantly increases the nuclear expression levels and promotes the biological effects of Nrf2 via the interaction with Cys151 in Keap1, which makes it a marvelous therapeutic candidate against a broad range of oxidative stress-related diseases, including type 2 diabetes (T2D), neurodegenerative diseases (NDs), cardiovascular diseases (CVDs), cancers, viral infections, and more recently SARS-CoV-2. Currently, the multifactorial property of the diseases and lack of adequate medical treatment, especially in viral diseases, result in developing new strategies to finding potential drugs. Curcumin potentially opens up new views as possible Nrf2 activator. However, its low bioavailability that is due to low solubility and low stability in the physiological conditions is a significant challenge in the field of its efficient and effective utilization in medicinal purposes. In this review, we summarized recent studies on the potential effect of curcumin to activate Nrf2 as the design of potential drugs for a viral infection like SARS-Cov2 and acute and chronic inflammation diseases in order to improve the cells' protection.

The effect of curcumin supplementation on recovery following exercise-induced muscle damage and delayed-onset muscle soreness: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

curcumin consumption may have a protective effect against exercise-induced muscle damage (EIMD) through stabilization of the cell membrane via inhibition of free radical formation. Evidence supporting a protective role of curcumin after physical activity induced muscle injury in humans, however, it is inconsistent.

METHODS

Medline, Scopus, and Google scholar were systematically searched up to May 2020. The Cochrane Collaboration tool for assessing the risk of bias was used for assessing the quality of studies. Random effects model, weighted mean difference (WMD), and 95% confidence interval (CI) were used for estimating the overall effect. Between-study heterogeneity was assessed using the chi-squared and I² statistic.

RESULTS

The results revealed a significant effect of curcumin supplementation on reducing creatine kinase (CK) (weighted mean difference [WMD] = -48.54 IU.L^-1 ; 95% CI: -80.667, -16.420; p = .003) and muscle soreness index decrease (WMD = -0.476; 95% CI: -0.750, -0.202; p = .001). Moreover, a subgroup analysis resulted in a significant decrease in CK concentrations and muscle soreness index, according to follow-ups after exercise, dose of curcumin, duration of studies, exercise type, train status and study design.

CONCLUSIONS

The current evidence revealed a efficacy of curcumin in reducing CK serum levels and muscle soreness index among adults. Therefore, curcumin may be known as a priority EIMD recovery agent in interventions.

In vitro Permeability and Bioavailability Enhancement of Curcumin by Nanoemulsion via Pulmonary Administration

Background:

Curcumin has shown considerable pharmacological activity, including antiinflammatory activity. Nevertheless, the pharmacological effect of curcumin may be limited because of poor water solubility, metabolizing rapidly and systemic elimination.

Objective:

In the current research, a novel curcumin nanoemulsion (Cur-NE) was developed for improving in vitro permeability and bioavailability via pulmonary administration.

Methods:

The Cur-NE was prepared by a modified emulsification-evaporation method and its surfac morphology, particles size and distribution, and encapsulation efficiencies of drug in NE were characterized. In vitro transmembrane transport experiment was performed to investigate the transport profile of curcumin across Xenopus alveolar membrane. The pharmacokinetics of Cur-NE in rabbits was evaluated.

Results:

The average particles size, zeta potential, polydispersity index of Cur-NE were 234.8±1.08 nm, -19.5±0.2 mV and 0.10, respectively. Xenopus alveolar membrane was used in the transmembrane transport study, the cumulative amount of curcumin was 6.6% for curcumin suspensions, but nearly 50% for Cur-NE at the time of 8 h (P<0.05). The pharmacokinetic study in rabbits, the absolute bioavailability of curcumin for Cur-NE was 24.11%.

Conclusion:

Thus, a novel Cur-NE for pulmonary drug delivery was developed for improving in vitro permeability and bioavailability, which can be an alternate to the oral administration.