Harnessing Nanocarriers to Overcome Bioavailability Barriers of HerbalActives: A Comprehensive Review

Plant-derived constituents (phytoconstituents) exhibit diverse pharmacological activities and have significant therapeutic potential for various diseases. However, their clinical application is often hindered by their poor solubility, instability, and low bioavailability (<10% in many cases). Nanotechnology-driven drug delivery systems provide innovative solutions to overcome these limitations and enhance the therapeutic efficacy of herbal compounds. However, major challenges remain, including concerns about long-term safety, potential toxicity, regulatory approval pathways, and reproducibility. Bridging the gap between preclinical promise and clinical translation remains a significant hurdle. A comprehensive review of studies (2019-2024) indexed in PubMed, Web of Science, Google Scholar, and ScienceDirect was conducted using keywords: "Phytoconstituents", "Bioavailability Enhancement", "Herbal Nanoformulations", "Nanocarriers", and "Herbal Medicine". Nanoformulations, such as solid lipid nanoparticles, polymeric nanoparticles, nanosuspensions, and phytosomes, have achieved significant improvements in pharmacokinetic profiles-for instance, a 9.17-fold increase in the oral bioavailability of curcumin, a 7-fold increase for naringenin, and a ~4.5-fold increase for piperine. These systems enhance solubility, stability, and targeted delivery, resulting in better therapeutic efficacy in preclinical studies. The findings highlight the potential of nanocarriers to transform the delivery of herbal actives by addressing traditional limitations. The observed multiple-fold enhancements in bioavailability affirm the promise of herbal nanoformulations. While nanotechnology significantly enhances the bioavailability and pharmacological potential of phytoconstituents, challenges persist, including clinical translation barriers, a lack of standardization due to herbal variability, scalability issues, and regulatory approval hurdles. Future research should focus on developing smart, stimuli-responsive nanocarriers, employing eco-friendly green synthesis methods, and establishing robust standardization protocols to achieve reproducible, safe, and effective herbal nanoformulations for clinical use. Future efforts must systematically address toxicity, regulatory clarity, and the standardization of large-scale manufacture to realize clinical potential.