Abstract
Ziziphus oxyphylla
and
Cedrela serrata
are Pakistan flora species with a reported use in jaundice and against liver diseases
1
, and with antioxidant and DNA protecting properties
2
, 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 IC
50
= 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 IC
50
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 IC
50
values for AGEs inhibition, ranging from 0.53 to 0.84 mg/mL, compared to aminoguanidine, IC
50
= 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.