Development and characterization of nanostructured lipid carrier loaded with flavonoid from selected local plant extracts for topical anti inflammatory application / Sharifah Sarah Shazwani

Sharifah Sarah Shazwani, Shahrulidzafa (2024) Development and characterization of nanostructured lipid carrier loaded with flavonoid from selected local plant extracts for topical anti inflammatory application / Sharifah Sarah Shazwani. PhD thesis, Universiti Malaya.

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Abstract

Topical drug delivery has a long history, dating back to ancient times, and has continuously evolved in modern medicine. It is now widely used, particularly in over-the-counter formulations. However, conventional topical preparations have encountered various issues. Consequently, scientific literature has started exploring alternative drug delivery systems, such as nanostructured lipid carriers (NLCs). NLCs offer benefits like improved bioavailability and efficacy of active ingredients like flavonoids by enhancing solubility, absorption pathways, stability, and improved occlusive effects on skin. In this study, flavonoid-rich extracts from local plants were loaded into NLCs and analyzed for particle size, zeta potential, morphology, encapsulation efficiency, and in-vitro release. These loaded-NLCs were then incorporated into a gel base, and the resulting formulation underwent evaluation for rheological properties, texture profile, drug release, and fitting into kinetic models. The NLCs were formulated using stearic acid, a mixture of medium-chain triglycerides (MCT) and oleic acid, tween 20, and span 20 through the hot-homogenization method. The optimized NLCs exhibited a particle size of 294.30±7.08 nm, a PDI of 0.23±0.01, and a zeta potential of -35.0±0.1 mV, with formulation SR8 being the optimal choice. Statistical analysis confirmed a strong fit for mean particle size, PDI, and zeta potential. MCT incorporation led to size reduction, demonstrating formulation adjustability. HPLC analysis revealed successful optimization of the aglycone Quercetin content in the extracts with approximately 200% increments in its content after the acid-reflux hydrolysis treatment. Additionally, the nitric oxide (NO) scavenging activity of the extracts was notable with approximately 50% to 54% efficacy in relative to the standard Quercetin compound. Encapsulation efficiency of the extract-loaded NLC also exceeded 90% at an optimal concentration of 0.6% to 2%. NLC with a 0.4% concentration of specific content demonstrated consistent particle size and was selected for further testing. Morphological evaluation confirmed stability and uniform particle distribution. Rheological analysis and gel studies validated optimal consistency and stability for topical use, with NLC-loaded gels exhibiting solid-like behavior and increased viscosity relative to the applied strain. Temperature-induced structural changes were observed during heating and cooling. In-vitro release studies emphasized controlled release properties, with loaded-NLCs fitting well into first-order kinetic models. Both loaded-gel and loaded-NLC gel favored Higuchi and Korsmeyer-peppas drug release kinetic models, respectively. Overall, this research covers various aspects, including flavonoid extraction, HPLC analysis, NO assay, NLC development, NLC optimization via Box-Behnken Analysis, loaded NLC characterization, NLC gel evaluation, and their applications. It underscores the significance of proper extraction techniques, demonstrates enhanced quercetin efficacy through acid hydrolysis, and confirms quercetin glycosides' anti-inflammatory properties via the NO assay. NLC development involves lipid and surfactant selection, BBD optimization ensures desired NLC properties, and physical evaluation validates gel stability and application. Morphological assessments demonstrate successful NLC integration in the gel matrix, enhancing stability and efficacy, while in-vitro studies emphasize controlled release. Kinetic models effectively describe release profiles for various carriers.

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