Review Article A Comprehensive Review on Quercetin-Loaded Nanoemulsions

Quercetin, a bioactive flavonoid widely found in fruits and vegetables, possesses potent antioxidant, anti-inflammatory, anticancer, and cardioprotective properties. However, its therapeutic utilization is limited by poor aqueous solubility, low permeability, rapid metabolism, and low oral bioavailability. To address these challenges, nanotechnology-based delivery systems, particularly nanoemulsions, have emerged as a promising approach to enhance the solubility, stability, and bioavailability of quercetin. Nanoemulsions are kinetically stable, nanosized dispersions of oil and water stabilized by surfactants and co-surfactants. Their high surface area, small droplet size, and ability to facilitate lymphatic transport significantly improve absorption and systemic delivery of lipophilic compounds like quercetin. Recent studies from 2020–2024 have demonstrated that quercetin-loaded nanoemulsions show enhanced pharmacokinetic and pharmacodynamic performance in various therapeutic areas, including cancer, neurodegenerative diseases, cardiovascular disorders, and inflammatory conditions. These formulations protect quercetin from oxidative degradation, prolong systemic circulation, and enable controlled drug release. Despite these advantages, challenges such as formulation stability, scale-up reproducibility, and regulatory acceptance remain. This review provides a comprehensive overview of the biological performance of quercetin-loaded nanoemulsions. It also highlights current advancements, limitations, and future perspectives in improving clinical applicability through green synthesis, Quality by Design (QbD), and targeted delivery approaches. Collectively, nanoemulsion technology represents a promising frontier in natural product-based drug delivery, offering enhanced bioefficacy and therapeutic potential for quercetin