Antioxidant activity of flavonoids

Emesis encompasses the forceful expulsion of the contents of stomach via the mouth or sometimes the nose.
The adverse effects of currently available anti-emetic agents potentiate the natural product researchers to explore the
natural anti-emetics with fewer side effects. The presented communication constitutes a review on anti-emetic effect of
two hundred and forty five plants belonging to seventy-eight families found in different parts of the world. It also
outlined the anti-emetic effect of plant extracts and isolated secondary metabolites studied through a variety of animal
models of emesis. The reported anti-emetic plants in different countries and cultures and the scientific studies on extracts
may help in the identification of promising single chemical compound(s) that may be used as a potential leads for
developing safe anti-emetic agents in future. Moreover the reported secondary metabolites having the same effect may
open the door for the search of same secondary metabolites from other natural sources. This review will provide useful
information for the discovery of natural anti-emetic compounds and fill the gaps in knowledge.

The aim of the present study was to investigate the antioxidant activity of methanolic extract of Michelia champaca flowers. Antioxidant activity was evaluated by using in-vitro assay models like Total antioxidant capacity, Nitric oxide radical scavenging assay, Reducing Power Assay and Hydrogen Peroxide Scavenging Activity. All the antioxidant activities were compared with standard antioxidant such as ascorbic acid. Methanolic extract of the plant showed effective free radical scavenging activity at 300µg concentration. The IC50 values of the ethanolic extract of Michelia champaca flowers were found to be 260 µg in total antioxidant activity, 150 µg in nitric oxide radical assay, 240 µg in reducing power assay and 280 µg in hydrogen peroxide assay. The results obtained in this study showed that the flowers of Michelia champaca have antioxidant properties which provide a basis for the traditional use of the plant.

Context: The Sechium edule fruit is grown and consumed because of their nutritional values in different countries of Latin America. Costa Rica is one of the most important producers and exporters. It is consumed as an antioxidant because its flavonoid content suggests such activity; however, the selection of varieties to crop does not involve the phytochemical profile of them. Aims: To characterize the phytochemical and antioxidant profile of the S. edule varieties grown in Costa Rica. Methods: The in vitro radical scavenging activity of different S. edule extracts were measured using DPPH and ORAC assays, as well as their inhibition of lipid peroxidation in rat liver and their redox potential by cyclic voltammetry. Flavonoids glycosides were isolated by HPLC and their structures were determined by NMR.Results: The S. edule varieties grown in Costa Rica showed a good radical scavenging activity and inhibition of lipid peroxidation; there were significant differences between varieties. In addition, the redox potential determined by electrochemical methods suggested the presence of flavonoids, which was confirmed by the isolation of apigenin 7-O-rutinoside and luteolin 7-O-rutinoside. Conclusions: The antioxidant potential of varieties of S. edule grown in Costa Rica was confirmed, identifying the 845 variety as the best antioxidant profile.

Context: Some flavonoids have been described as neuroprotectors. Gossypitrin (Gos) is a natural occurring flavonoid and the main bioactive substance from the flowers of Talipariti elatum Sw. (Majagua azul), traditionally used in Cuba as expectorant and antiasthmatic. Only few reports have documented its antioxidant properties.

Aims: To evaluate the antioxidant and cytoprotective effects of Gos against cyanide-induced oxidative stress and cell death in PC12 cells.

Methods: Gos effects on DPPH/ ABTS radical scavenging, ferric reducing power and lipid peroxidation were examined. The ischemia/reperfusion neuronal damage was produced by exposing PC12 cells to KCN in glucose-free medium. Gos was added to the incubation medium 30 min before chemical hypoxia induction. The neuroprotective potential of Gos was assessed by measuring cell viability by the MTT assay, the antioxidant enzymes SOD and CAT, and GSH and lipid peroxidation levels. Rutin (Rut), the well-known antioxidant, was used as a reference compound.

Results: Gos showed a potent intrinsic antioxidant capacity evidenced by low IC50 and EC50 values for DPPH/ABTS/malondialdehyde and ferric reducing power, respectively. Pre-treatment of PC12 cells with Gos, significantly increased their survival against KCN, restored the levels of GSH and the SOD and CAT enzymes activities, as well as reduced the level of lipid peroxidation. Its antioxidant effects were higher than those elicited by Rut.

Conclusions: The results show for the first time the neuroprotective potential of Gos against hypoxic cell damage, probably associated to its antioxidant effects.

Emesis encompasses the forceful expulsion of the contents of stomach via the mouth or sometimes the nose. The adverse effects of currently available anti-emetic agents potentiate the natural product researchers to explore the natural anti-emetics with fewer side effects. The presented communication constitutes a review on anti-emetic effect of two hundred and forty five plants belonging to seventy-eight families found in different parts of the world. It also outlined the anti-emetic effect of plant extracts and isolated secondary metabolites studied through a variety of animal models of emesis. The reported anti-emetic plants in different countries and cultures and the scientific studies on extracts may help in the identification of promising single chemical compound(s) that may be used as a potential leads for developing safe anti-emetic agents in future. Moreover the reported secondary metabolites having the same effect may open the door for the search of same secondary metabolite...

Context: Caesalpinia bahamensis Lam. is a medicinal plant used by the Cuban population to treat renal and hepatic diseases. However, this species lacks scientific studies that support its biological applications.

Aims: To evaluate the chemical composition and the antioxidant capacity of fractions obtained from the stem of Caesalpinia bahamensis Lam.

Methods: A continuous extraction of the stem was made by maceration using a battery of solvents of increasing polarity: chloroform, ethyl acetate and methanol. All fractions were analyzed by TLC and phytochemical screening. The compounds of the chloroform fraction were identified by GC/MS, while the ethyl acetate and methanol fractions were characterized by UV-Vis spectroscopy. The antioxidant capacity was evaluated by the DPPH and FRAP assays.

Results: Ten compounds were identified by GC/MS of the chloroform fraction, associated with fatty acids, terpenoids and phytosterols. The major compounds of this fraction were octacosanol, monopalmitin and palmitic acid. The presence of flavonoids in the ethyl acetate and methanol fractions was demonstrated by phytochemical screening, TLC and UV spectroscopy. The three fractions showed antioxidant capacity in the DPPH assay, with the methanol fraction (IC50=11.1 µg/mL) being the most active. The ethyl acetate fraction (equivalent to 100.7 µmol ascorbic acid) and the methanol fraction (equivalent to 37.3 µmol ascorbic acid) showed antioxidant capacity in the FRAP assay at concentrations of 125 µg/mL and 1000 µg/mL, respectively.

Conclusions: The fractions evaluated showed antioxidant capacity in the DPPH and FRAP assays, possibly associated with the presence of phenols and flavonoids.