Synthesis of chitosan-modified poly (lactic-co-glycolic acid) microparticles with pH-dependent controlled-release kinetics to enhance the delivery of potential antidiarrheal medicinal plant extract to the lower gastrointestinal tract

Phytotherapy has been used to treat gastroenteritis in many African countries, with medicinal plant extracts from Grewia tenax, Corchorus tridens, and Lantana camara showing strong antibacterial properties against bacteria that cause gastroenteritis. However, issues such as uncontrolled metabolism by gastric juices and instability in the gastrointestinal tract due to varying pH levels reduce the effectiveness of these phytomedicines. This has limited their use as an alternative or complementary treatment for gastroenteritis. To address this, nanotechnology has been employed to improve the pharmacokinetic and pharmacodynamic properties of phytomedicines. This study aimed to develop biodegradable, plant-based, chitosan-modified poly(lactic-co-glycolic acid) (CMPLGA) microparticles for targeted release in the lower gastrointestinal tract. Nanoparticles were created by mixing 12. 5 mg/ml of polymers with 120 mg/ml of antibacterial extracts from G. tenax, C. tridens, and L. camara using a modified double emulsion (W 1/O/W 2) and solvent evaporation method. The size and zeta potential of the nanoparticles were measured using photon correlation spectroscopy and electrophoretic laser Doppler anemometry. Scanning Electron Microscopy was used to examine morphology, and the encapsulation efficiency was determined via UV- vis spectroscopy. In vitro, the release kinetics of the plant extracts from the nanoparticles were investigated using sample separation techniques in simulated gastric and intestinal fluids, without the presence of enzymes. The plant-based CMPLGA nanoparticles were spherical, with sizes ranging from 524 ± 18 nm. 92 nm to 2582 ± 123 nm, and zeta potential from 2. 68 ± 0. 08 mV to 44. 2 ± 0. 100 mV; encapsulation efficiency was greater than 89.8%. The release of phytomedicine from the nanoparticles depended on pH, with less than 2% release at pH 1. 2 and over 50% release at pH 7. 7.4. These CMPLGA nanoparticles improved the stability of the antibacterial phytomedicine in acidic conditions similar to those in the upper GI tract. They may serve as an effective vehicle for future drug delivery targeting gastrointestinal pathogens in the lower GI tract.