Improved antioxidant, antimicrobial and anticancer activity of naringenin on conjugation with pectin

The purpose of the present study was to improve the aqueous solubility of naringenin by conjugating with water-soluble polysaccharide carrier, pectin. The pectin-naringenin conjugate was synthesized employing dicyclohexylcarbodiimide and dimethylaminopyridine. The conjugation was confirmed by various physicochemical characterizations. The results of differential scanning calorimetry, X-ray diffraction and morphological analyses revealed semi-crystalline nature of the conjugate. The chromatographic analysis showed 37.069 µg naringenin/mg of conjugate. The conjugate was determined to have molecular weight of 6.22 × 10⁴ kDa by static light scattering. In silico molecular mechanistic simulations performed for pectin and naringenin revealed the energetic and geometrical stability within the polysaccharide-polyphenol conjugate. The critical aggregation concentration was in the range of 44.67-56.23 μg/mL as determined by dynamic light scattering and fluorescence spectroscopy. On in vitro release, 99.4% (pH 1.2) and 57.62% (pH 7.4) of naringenin were found to be released over a period of 30 h and 48 h, respectively. Further, the release of naringenin followed Higuchi's square-root kinetics with diffusion as the possible release mechanism. A comparative evaluation for antioxidant activity revealed a significantly higher radical scavenging activity of conjugate over the naringenin. Further, the conjugate exhibited significantly higher antimicrobial action against Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa while a comparable antimicrobial activity was observed against Escherichia coli and Bacillus subtilis. The cytotoxicity studies of the synthesized conjugate showed anti-cancer activity against NIH: OVCAR-5 cells. In conclusion, the pectin-naringenin conjugate presented hydrocolloidal properties with improved therapeutic efficacy and delivery over the native polyphenol.