Chiang Mai Journal of Science

 In this study the phenolics in Plumbago zeylanica extract was quantified using high performance thin layer chromatography (HPTLC). The free radical scavenging activity was evaluated using in vitro antioxidant assays, along with anti-inflammatory activity by diene-conjugate and b-glucuronidase assay. The results for antioxidant and anti-inflammatory effects were compared using trolox and salicylic acid as standards, respectively. The HPTLC analysis showed presence of quercetin and rutin (Rf values 0.96 and 0.54, respectively). Xanthine oxidase inhibition was studied using cow milk xanthine oxidase and comparing with allopurinol as a standard drug. The HPTLC quantification of flavonoids has been validated using a mobile phase, ethyl acetate: methanol: formic acid: water (20:5:2:3, v/v), at UV-254 nm. The total phenolic and flavonoid content of extract was 286 and 260 mg gallic acid equivalent (mg of GAE/g) of extract whereas, the total flavonoid content was 242 and 208 mg quercetin  equivalent (mg of QE/g). The Plumbago zeylanica extract revealed remarkable antioxidant  and XO inhibitory activity showing 92% and 86.5% inhibition (IC50 10.5 and 9.2 mg), at  100 mg/mL. In comparison with a positive control allopurinol, which showed 90.1% inhibition (IC50 12.5 mM) at 100 mg/mL, respectively. The results for anti-inflammatory activity by root extract (45.1 to 88.5%), for diene-conjugate (40.2 to 86.2%) for b-glucuronidase assay and  for shoot extracts extract (38.5 to 75.2%) for diene-conjugate and (30.6 to 70.1%) for  b-glucuronidase assay, respectively, as compared with salicylic acid as standards. These findings confirmed that the P. zeylanica root and shoot extracts has potent free radical scavenging,  anti-inflammatory and xanthine oxidase inhibitory activities.