Flavonoids have known anti-inflammatory and antioxidative actions, and they have been described as neuroprotective and able to reduce damage in CNS diseases. We evaluated the action of the flavonoid rutin in an animal model of focal cortical ischemia induced by unilateral thermocoagulation of superficial blood vessels of motor (M1) and somatosensory (S1) primary cortices. Ischemic rats were submitted to daily injections (i.p.) for five days, starting immediately after induction of ischemia. We tested two doses: 50mg/kg or 100mg/kg of body weight. Sensorimotor tests were used to evaluate functional recovery. Bioavailability in plasma was done by chromatographic analysis. The effect of treatment in lesion volume and neurodegeneration was evaluated 48h and 72h after ischemia, respectively. We observed significant sensorimotor recovery induced by rutin, and the dose of 50mg/kg had more pronounced effect. Thus, this dose was used in further analyses. Plasma availability of rutin was detected from 2h to at least 8h after ischemia. The treatment did not result in reduction of lesion volume but reduced the number of degenerated neurons at the periphery of the lesion. The results suggest rutin as an efficient drug to treat brain ischemia since it was able to promote significant recovery of sensorimotor loss, which was correlated to the reduction of neurodegeneration in the periphery of cortical injury. Increasing studies with rutin and other flavonoids might give support for further clinical trials with these drugs.
Flavonoids are a significant group of secondary metabolites in plants. Many of these compounds are potent antioxidants, being an important part in food products derived from the plants. The current status of research on flavonoid compounds in the fruit of Saskatoon berries (Amelanchier alnifolia Nutt.) and their health promoting effects, including recommended utilization, are reviewed. The major classes of flavonoids in the fruit are flavonols (quercetin and rutin), flavanes (proanthocyanidin compounds ranging from dimers through to heptamers and even higher polymers) and finally anthocyanins. The flavonoids represented the group of polyphenols that mostly contributed to the antioxidant activity of Saskatoon berries. High content of the flavoinoids antioxidants in the fruit is responsible for the observed anti-inflammatory, antidiadiabetic and chemo-protective effects.
The LC-MS/MS technique was applied to the stability study of several flavonoids and phenolic acids in honey samples during the ultrasonic extraction (USE) and microwave-assisted extraction (MAE). Phenolic compounds from the standard mixture were stable under ultrasounds action with the mean recovery of (90.4%±7.1%), but during microwave-assisted extraction the benzoic acid derivatives and aglycones of flavonoids showed lower recovery (70-80%). In honey matrix, the phenolic acids and the glycosides exhibited the high stability for MAE and USE treatments. However, the recoveries of tested aglycones were below 10%. In the presence of an artificial sugar matrix, flavonols were almost completely degraded after successive treatment under MAE and USE conditions. The obtained results indicated that standard addition method for flavonoids quantification in honey samples should not be recommended. Application of the USE conditions provided higher and/or similar extraction yields for phenolic acids than usually applied shaking with solvent. It also allowed shortening the time required for the whole sample preparation procedure. Phenolic acids and glycosides such as quercetrin, rutin and hesperidin appeared to be stable under such conditions.
Quercetin, rutin, naringenin, epicatechin are flavonoids with diverse properties, including antioxidant potential. We evaluated, in vitro, the cytotoxicity of these flavonoids (20, 30, 50, 100, 200, 400μM) in swim-up selected human sperm. Antioxidant activity was tested against tert-butylhydroperoxide induced lipid peroxidation using a C11-BODIPY(581/591) probe and transmission electron microscopy. A significant concentration-dependent effect on sperm viability (P<0.001) and motility (P<0.001) was observed. Lipid peroxidation was decreased in samples treated with 30μM quercetin (P<0.01) and 30μM rutin (P<0.05) versus samples incubated with tert-butylhydroperoxide alone. Naringenin (50-100μM) showed a low protective effect and epicatechin (200μM) was not efficacious. Transmission electron microscopy analysis confirmed the protective action of rutin and in particular quercetin on damages induced by lipid peroxidation. These results underlined the antioxidant properties of quercetin and rutin. A possible role of these compounds in the supplementation of media used during semen handling warrants attention and further studies.
Flavonols kaempferol, quercetin, myricetin and gossypetin, and flavones apigenin, acacetin, luteolin, orientin and tricin, are subjected to two AlCl(3) spectrophotometric methods used for determination of total flavonoid content. The method developed by Woisky and Salatino involves addition of AlCl(3) solution to the flavonoid solution and recording of optical density at 420nm. All flavonols except kaempferol have absorption maxima above 440nm and so readings at 420nm are erroneous. Among flavones, all except for luteolin and orientin, have absorption maxima below 400nm. Further, addition of CH(3)COOK and recording the absorbance at 415nm, as modified by Chang et al., works well for flavonols kaempferol, quercetin and myricetin, but not for gossypetin. The flavones luteolin and orientin absorbed above 400nm, whereas all others absorbed below 400nm. Examination of the results of both methods indicates they are inadequate, and should not to be considered as universal and standard methods for total flavonoid determination.
BACKGROUND: Buckwheat flour and buckwheat sprouts possess antioxidant properties, and previous studies have reported on buckwheat flour displaying an inhibitory activity for angiotensin-I converting enzyme (ACE). Information is lacking on the bioactivity of other parts of the buckwheat, such as the seed hulls and plant stalks. This study investigates the ACE inhibitory activity and antioxidant activity of various parts of 2 types of buckwheat, namely, common buckwheat (Fagopyrum esculentum Moench) and tartary buckwheat (Fagopyrum tataricum Gaertn). METHODS: For high throughput screening, we used a microplate fluometric assay to evaluate the ACE inhibitory effects of various extracts and the ferric-reducing antioxidant power (FRAP) assay to evaluate antioxidant activity. RESULTS: The extract of common hulls extracted using 50% (v/v)-ethanol solvent presented a remarkable inhibitory activity. The value of IC50 is 30 g ml-1. The extracts of both common and tartary hulls extracted using 50% (v/v)-ethanol solvent demonstrated an antioxidant activity that is superior to that of other extracts. CONCLUSION: This study determined that the ethanolic extract of the hulls of common buckwheat presented more favorable antioxidant and ACE inhibitory abilities. However, the correlation of antioxidant activity and ACE inhibitory activity for all 18 types of extracts is low. The ACE inhibitory activity could have been caused by a synergistic effect of flavonoids or from other unidentified components in the extracts. The ethanolic extract of common hulls demonstrated remarkable ACE inhibitory activity and is worthy of further animal study.
Because of their health-promoting properties, flavonoids are used in feed supplements for ruminants, although scientific evidence for their efficacy in vivo is limited. It has been shown recently that bioavailability of quercetin is low after ruminal administration in cows because of degradation by the ruminal microbiota. It is unknown whether quercetin could be absorbed from the small intestine in ruminants if degradation is prevented; therefore, we investigated the bioavailability of quercetin after duodenal administration in 6 German Holstein cows. On 88 ± 3 d in milk, each cow received equivalent doses of quercetin [9, 18, or 27 mg of quercetin equivalents (QE)/kg of body weight] either as quercetin aglycone (QA) or as its glucorhamnoside rutin (RU). In addition, 2 control studies with duodenal administration of NaCl solution (0.9%) were conducted per cow to examine concentrations of flavonoids in plasma during regular feeding. Blood samples were collected at defined time intervals over a period of 24 h before and after administration of the test compounds. A washout period of 2 d was applied between the runs to avoid possible carryover effects. Concentrations of plasma quercetin aglycone and its metabolites isorhamnetin, tamarixetin, and kaempferol were measured after treatment with glucuronidase/sulfatase by HPLC with fluorescence detection. After administration of RU, levels of plasma quercetin did not increase above baseline, irrespective of dose administered. After duodenal administration of QA, the plasma concentration of QA and its methylated metabolites clearly increased above baseline. The maximal plasma concentrations of total flavonols (about 2 h after application) increased in a dose-dependent manner but showed high interindividual variability (range 368.8 to 983.3 nmol/L at 27 mg of QE/kg of body weight) but peak time did not differ. Preadministration baseline values of total flavonols were reached again 3 to 4 h after QA administration. The bioavailability of quercetin and its metabolites, as measured by the area under the concentration-time curve, was affected by the quercetin source applied, whereby quercetin from RU was unavailable. Taken together, duodenal administration enhanced bioavailability of QA almost to values previously reported in pigs after oral administration of QA. In contrast to findings in monogastrics or after oral administration in cows, quercetin from RU seems to be unavailable when administered duodenally.
A new acylated kaempferol glycoside, kaempferol 3-O-α-l-rhamnopyranosyl-(1 → 6)-O-[β-d-glucopyranosyl-(1 → 2)-4-O-acetyl-α-l-rhamnopyranosyl-(1 → 2)]-β-d-galactopyranoside, has been isolated from the leaves of Tipuana tipu (Benth.) Lillo growing in Egypt, along with three known flavonol glycosides, kaempferol 3-O-rutinoside, quercetin 3-O-rutinoside (rutin) and kaempferol 3-O-[α-l-rhamnopyranosyl-(1 → 6)]-[α-l-rhamnopyranosyl-(1 → 2]-β-d-glucopyranoside. Structure elucidation was achieved through different spectroscopic methods. Structure relationship with anti-inflammatory activity using carrageenin-induced rat paw oedema model is discussed.
Two new prenylated flavonoids, thunbergiols A (1) and B (2), along with three known compounds, chrysin (3), quercetin (4) and berberine (5) were obtained from the methanolic extract of roots of Berberis thunbergii DC. MS, NMR and other spectroscopic techniques were employed for their structural characterisation.
Unlike the case of conventional drug formulations, dissolution tests have hitherto not been required for herbal medicinal products commercially available in South Africa. This study investigated dissolution of the South African Sutherlandia frutescens using selected flavonoid glycosides as marker compounds. Dissolution of markers was assessed in three dissolution media at pH 1.2, 4.5 and 6.8, and samples were analysed using a validated HPLC method. The dissolution profile of each marker varied for the different materials investigated. All three media utilised showed differences in flavonoid glycoside dissolution between the S. frutescens products evaluated, with f2 values < 50 for comparison of flavonoid dissolution from any two of the materials. Dissolution of S. frutescens materials could thus be characterised using the markers in all the media tested. This tool may be employed in the future for comparison of orally administered S. frutescens products, provided between- batch variability is evaluated and found less than between-sample variability.