Abstract
This study investigated the phytochemical constituents and antioxidant properties of crude extracts of C. argentea at different maturity stages and seasons. Total phenols, flavonoids, and proanthocyanidin content from water, acetone and methanol extracts were evaluated spectrophotometrically. The antioxidant activities were measured using 2,2- diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), Ferric reducing antioxidant power (FRAP) and Total antioxidant capacity (TAC) models. Results showed that the flowering stages in all the solvent extracts gave the highest polyphenolic content with the acetone extract significantly higher than the methanol and aqueous extracts (P < 0.05). The highest value for total polyhenolic content 80.75 ± 4.21 for the first trial and 89.69 ± 2.13 μg/mL in the second trial; while the flavonoids was 874.76 ± 7.87 and 946.19 ± 7.87 μg/mL in the first and second trials respectively; and proanthocyanidin content was 170.00 ± 0 and 100.90 ± 1.29 μg/mL. Overall, the aqueous extracts had the lowest content of all the phytochemicals. The antioxidant activities ranged from low to high at different growth stages of the plant. While low to no activity was observed in the aqueous extracts in all the assays, the methanol extracts of the flowering stages showeds the best activity in the first and second trials with IC50 values of 104.10 ± 8.59 and 120.02 ± 13.37 μg/mL respectively in ABTS. Similar trend was obtained in the DPPH assay with the highest activity in the methanol flowering extract with IC50 of 52.36 ± 0.76 μg/mL (first trial) and 49.36 ± 0.29 μg/mL (second trial). The FRAP and TAC also had the highest activity in the flowering stages in all solvents, but with the acetone extracts having the overall inhibition on both radicals. This study revealed that Celosia argentea phytoconsituents and antioxidant potential can be influenced by physiological and developmental stages of the plant.
Highlights
Increased exposure to the environment, higher levels of dietary xenobiotics and cellular metabolism leads to the production of free radicals in the body
The highest yield was obtained with the aqueous extract in all growth stages; APRE (35.6 g, 22.57%), AFLW (90 g, 30.93%), and aqueous post flowering (APST) (110.2 g, 35.73%), followed by methanol extracts; methanol extracts where the preflowering stage (MPRE) (34.3 g, 12.78%), methanol flowering (MFLW) (79 g, 12.45%) and methanol post flowering (MPST) (100.4 g, 7.66%)
Apart from the increase yield observed for the acetone extract of the preflowering stage of the second trial, the same trend was observed in the resultant yield of the solvent extracts of other growth stages of the second trial
Summary
Increased exposure to the environment, higher levels of dietary xenobiotics and cellular metabolism leads to the production of free radicals in the body. Free radicals form reactive oxygen species (ROS) such as the hypohalite, super oxide anion, hydroxyl radicals and hydrogen peroxide. These radicals have been directly connected to various pathological conditions including the increase in pathogenesis of atherosclerosis, diabetes mellitus, multiple sclerosis, aging and several other oxidative damages (Nimse and Pal, 2015). Antioxidants are molecules that can considerably impede or foil the toxic oxidative processes, even at very low concentrations They can either be synthesized in vivo (reduced glutathione, superoxide dismutase and catalase) or consumed as dietary supplements such as vitamin C, selenium, vitamin E and carotenoids (Kasote et al, 2015). Supplementation with dietary antioxidant (either as food or herb) has gained greater recognition because of their ability to hinder the progressive production of free radicals, obstruct the actions of ROS-generating enzymes (nitric oxide, synthase and xanthine oxidase) and improve the endogenous cellular antioxidant mechanisms such as the up-regulation of the activity of catalase and super oxide dismutase (Kurutas, 2015)
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