Anti-oxidant and anti-glycation constituents from Ziziphus oxyphylla and Cedrela serrata

Ziziphus oxyphylla and Cedrela serrata are Pakistan flora species with a reported use in jaundice and against liver diseases¹, and with antioxidant and DNA protecting properties², respectively. In the present study a bioassay-guided fractionation procedure was used to isolate antioxidant constituents from the leaves of Z. oxyphylla and C. serrata. Ethyl acetate fractions showed the higher DPPH scavenging activity and therefore they were further subjected to purification by flash chromatography. Seven compounds (1-7) from Z. oxyphylla and five (8-12) from C. serrata were isolated through semi preparative HPLC and were evaluated in various radical scavenging assays. Compounds 1, 2 (quercetin-3-O-glucoside and 3-O-galactoside in a different ratio), and 8 (kaempferol-3-O-glucoside), with IC₅₀= 5.33, 7.95 and 4.36 µg/mL, respectively, had significant DPPH scavenging activity compared to quercetin (3.6 µg/mL) (p= 0.05). Similarly, the superoxide and ABTS assays indicated IC₅₀ values ranging from 0.21 to 0.91 mg/mL and 0.17 to 0.32 mg/mL, respectively. All isolated compounds were identified as flavonoids, more in particular quercetin and kaempferol glucosides (monoglucosides such as quercetin-3-O-glucoside, quercetin-3-O-galactoside, quercetin-3-O-rhamnoside, kaempferol-3-O-glucoside, kaempferol-3-O-galactoside, and diglucosides). Furthermore, these compounds were potent inhibitors of the formation of advanced glycation end products (AGEs) in a protein glycation assay. Most of the compounds had low IC₅₀ values for AGEs inhibition, ranging from 0.53 to 0.84 mg/mL, compared to aminoguanidine, IC₅₀= 0.51 mg/mL, used as positive control.

References:

[1] Shah SR et al., 2006. Pak Journal of Weed Science Research. 12, 199 – 211.

[2] Perveen F et al., M., 2012. Journal of Natural Products India 5, 207 – 213.