Formulation of saponin stabilized nanoemulsion by ultrasonic method and its role to protect the degradation of quercitin from UV light

• Saponin stabilized nanoemulsion was prepared by sonication method.
• Interaction between bile salts and quercitin studied in nanoemulsion.
• Nanoemulsion suppressed the degradation of quercitin from UV light.
• The antioxidant activity of curcumin and quercitin was compared in nanoemulsion.

The objective of the present study was to prepare quercitin (QT) loaded o/w nanoemulsion using food grade surfactants (saponin and tween 80). The prepared nanoemulsion) was stable up to 30 days. The average particle size of the nanoemulsion was 52 ± 10 nm. The formation of saponin stabilized nanoemulsion was confirmed by transmission electron microscopy. Quercitin (QT) trapped nanoemulsion showed higher stability on exposure to UV light (254 nm) as compared to water/ethanol system. The degradation rate was found to decrease from 9 ± 1%, 11 ± 1% at pH 7.4, 8.0 respectively as compared to 42 ± 2% in water/ethanol system. Attempt was also made to study the interaction of QT with two different bile salts (sodium cholate and sodium taurocholate). The free radical scavenging activity of DPPH quercitin and curcumin was compared in NEm media. The obtained IC50 value of quercitin, curcumin and ascorbic acid are 28.88 ± 1, 45.53 ± 2 and 51.51 ± 2 μM respectively. The values of binding constant for sodium cholate (NaC) and sodium taurocholate (NaTC) are 2.66 × 105 and 2.72 × 104 M−1 respectively. Sodium cholate (NaC) was found to show strong interaction towards quercitin (QT) due to more electron density on oxygen atom of carboxylate ion.