Identification and in vitro biological activities of flavonols in garlic leaf and shoot: inhibition of soybean lipoxygenase and hyaluronidase activities and scavenging of free radicals

Abstract

We isolated four flavonols from garlic (Allium sativum L) leaf and shoot and measured the in vitro antioxidant activity of the isolated flavonols and their aglycones. The chemical structures of the compounds were shown to be quercetin 3-O-β-D-glucopyranoside (isoquercitrin), quercetin 3-O-β-D-xylopyranoside (reynoutrin), kaempferol 3-O-β-D-glucopyranoside (astragalin) and isorhamnetin 3-O-β-D-glucopyranoside based on FAB-MS and NMR analyses. Assays of DPPH (1,1-diphenyl-β-picryl hydrazyl) and hydroxyl radical scavenging, inhibition of linoleic acid peroxidation, and soybean lipoxygenase (LO) and hyaluronidase (HYA) inhibition were used to evaluate the antioxidant activity. Quercetin and its glycosides showed the highest antioxidant activity among the compounds. In the LO assay, the IC 50 values of quercetin, isoquercitrin and reynoutrin were 16.9, 40.1 and 32.9 µM respectively. Quercetin was the most effective among the flavonols. In the HYA assay the IC 50 values of quercetin, isoquercitrin and reynoutrin were 23.0, 20.9 and 22.1 mM respectively. Isoquercitrin had the most potent inhibitory activity on HYA. The inhibition patterns of the flavonols on LO and HYA were elucidated as mixed types of competitive and non-competitive inhibition according to Lineweaver-Burk plot results.Although most garlic shoots and leaves are discarded and not used at present, our results suggest that ancillary garlic parts could be utilised as functional foods or ingredients.

Interactions among genotype, environment and agronomic practices on production and quality of storage onion (Allium cepa L.) - A review

“…Polyphenols include a great range of molecular structures and they show important antioxidant activities in dietary plants (Rice et al 1997;Paganga et al 1999;Boyle et al 2000;Kim et al 2005): in fact, they protect human organism against cellular damage (Dimitrios 2006) and, accordingly, they prevent chronic diseases Hertog, Hollman 1996;Diplock et al 1998;Lampe 1999). Notably, oxidation of DNA, proteins and lipids by reactive oxygen species (ROS) play an important role in aging and in a wide range of common diseases, including cancer and cardiovascular, inflammatory and neurodegenerative diseases, such as Alzheimer's, and other age-related degenerative conditions (Borek 1997;Richardson 1993).…”

Isolation and anti-inflammatory effect of astragalin synthesized by enzymatic hydrolysis of tea seed extract

“…A minute quantity of AS can be isolated from various plants such as persimmon leaves,17 Eucommia ulmoides leaves,18, 19 Solenostemma argel ,20 garlic leaf and shoot,21 and the seeds of Centaurea schischkinii 22. Even though the antipruritic effect,23 glycation inhibitory activities of AS,18 and its potential as an alternative medicine for allergic diseases17 have been reported, the rareness of AS in nature has prevented its widespread study and application.…”

Comparison of the Preventive Activity of Isorhamnetin Glycosides from Atsumi-kabu (Red Turnip,Brassica, campestrisL.) Leaves on Carbon Tetrachloride-Induced Liver Injury in Mice

“…The tricloromethyl radical produced from carbon tetrachloride by its dechlorination from the action of cytochrome P450 isozymes is thought to induce the formation of the lipid radical and consecutive lipid peroxidation to finally cause liver cell damage. 15) Leaves of atsumi-kabu (2.7 kg dry weight), which had been dried in a room at about [20][21][22][23][24][25] C with ventilation, were extracted with methyl alcohol (MeOH) under reflux. The evaporated extract was dissolved in MeOH and mixed with chloroform and distilled water in the ratio of 0.5:1:2 (v/v/v).…”

“…19) However, as the radical scavenging of isorhamnetin as an aglycone of isorhamnetin 3-O-glucoside is weaker than that of quercetin, a dose which have been in excess was used in this experiment. 20) Sixty ml of a CCl 4 solution composed of olive oil and CCl 4 in a volume ratio of 1:1 was intraperitoneally injected 30 min after the oral administration of a 0.5% carboxyl methyl solution with or without each sample (for the CCl 4 , Iso 1, Iso 2 and Quer groups). To the control group, only 30 ml of olive oil was intraperitoneally injected 30 min after oral administration of the 0.5% carboxyl methyl solution.…”