Đánh giá hoạt tính sinh học in vitro của cao hoa sao nhái hoa vàng định hướng hỗ trợ điều trị gout (Cosmos sulphureus Cav.)

Gout is an inflammatory arthritis caused by hyperuricemia. Gout treatment is aimed at inhibiting the enzyme xanthine oxidase (XO), which is an enzyme related to uric acid formation. In this study, Cosmos sulphureus flowers extract and its fractions was evaluated for the antioxidant, anti-inflammatory and xanthine oxidase inhibitory activities in vitro. Methods: Dried powder of Cosmos sulphureus flowers was percolated in 70% aqueous-ethanol with a ratio of material and solvent of 1:20 w/v. Crude extract was fractioned using liquid-liquid extraction with different solvents of n-hexane, ethyl acetate and n-butanol. Total polyphenols and flavonoids contents were determined by UV-Vis spectrophotometry when colored with Folin-Ciocalteu reagents and aluminum chloride method expressed as gallic acid and coreopsin equivalents, respectively. The capacity of antioxidants of Cosmos sulphureus extracts was assessed in DPPH and ABTS radicals scavenging method. The anti-inflammatory activities was performed by the proteinase inhibitory activies. The capacity of xanthine oxidase inhibition activity of the Cosmos sulphureus extracts was determined the concentration of uric acid measuring by the absorption at wavelength of 295 nm. Results: There was a wide range of polyphenols and flavonoids contents in Cosmos sulphureus flowers extract and its fractions (except for n-hexan fraction), the value varied from từ 88.23 ± 9.66 to 719.49 ± 10.06 mgGAE/g for polyphenols and from 26.21 ± 1.27 to 208.12 ± 11.85 mgCE/g for flavonoids. The antioxidant experiment using DPPH test suggests that all extracts of Cosmos sulphureus was capable of scavenging free radicals. The inhibition of DPPH reached 50% with an IC50 as follows 13.29 ± 0.22 g/mL for crude extract, 7.1 ± 0.08 g/mL for ethyl acetate fraction, 23.69 ± 0.20 g/mL for n-butanol fraction, 139.68 ± 0.67 g/mL for aquarius fraction and 112.93 ± 1.55 g/mL for n-hexan fraction, respectively. All of Cosmos sulphureus extracts elicited a dose dependent inhibition of xanthine oxidase. The IC50 results showed that the strongest activity was observed with ethyl acetate fraction (IC50 = 89.70 ± 1.09 μg/mL). The following experiments indicates that ethyl acetate fraction (IC50 = 90 μg/mL) is a potent xanthine oxidase inhibitor, showed a mixed-type of inhibition pattern. Conclusions: All of the extracts from the Cosmos sulphureus flowers have strongly antioxidant activities, scavenging DPPH and ABTS free radicals, anti-inflammatory and inhibitory enzyme xanthine oxidase in vitro. The Cosmos sulphureus flower was a potential materials for product a preparations to support the treatment of gout.