Total phenol, antioxidant and free radical scavenging activities of some medicinal plants

Polyphenolics from various extracts/fractions of red onion (Allium cepa) peel with potent antioxidant and antimutagenic activities

In order to determine antioxidant activity, the five extracts/fractions of red onion peel were studied for their total content of phenolics (TPC), flavonoids (TFC), antioxidant activity (AOA), free radical scavenging activity (FRSA), assayed by DPPH radical in the terms of anti-radical power (ARP) and reducing power (RP), expressed as ascorbic acid equivalents (ASE)/ml. High TPC (384.7 +/- 5.0 mg GAE/g), TFC (165.2+/- 3.2 mg QE/g), AOA (97.4 +/- 7.6%), ARP (75.3 +/-4.5) and RP (1.6 +/-0.3 ASE/ml) were found for the ethyl acetate (EA) fraction. EA fraction had markedly higher antioxidant capacity than butylated hydroxytoluene (BHT) in preventive or scavenging capacities against FeCl3-induced lipid peroxidation, protein fragmentation, hydroxyl (site-specific and non-site-specific), superoxide anion and nitric oxide radicals. EA fraction also showed dose dependent antimutagenic activity by following the inhibition of tobacco-induced mutagenicity in Salmonella typhimurium strains (TA102) and hydroxyl radical-induced nicking in plasmid pUC18 DNA. HPLC and MS/MS analysis showed the presence of ferulic, gallic, protocatechuic acids, quercetin and kaempferol. The large amount of polyphenols contained in EA fraction may cause its strong antioxidant and antimutagenic properties. This information shows that EA fraction of red onion peel can be used as natural antioxidant in nutraceutical preparations.

Radioprotective properties of polyphenols from Phyllanthus amarus Linn

Radioprotective activity of pure compounds isolated from the plant Phyllanthus amarus was studied using rat liver mitochondria and pBR322 plasmid DNA as an in vitro model system. These compounds were ellagitannins namely amariin, 1-galloyl-2,3-dehydrohexahydroxydiphenyl (DHHDP)-glucose, repandusinic acid, geraniin, corilagin, phyllanthusiin D, and flavonoids namely rutin, and quercetin 3-O-glucoside. The activity was then correlated with their hydroxyl and superoxide radical scavenging activity. Both ellagitannins and flavonoids effectively prevented lipid peroxidation and protein oxidation in mitochondria. The compounds also prevented radiation induced single strand breaks in pBR322 plasmid DNA. The radioprotective activity of ellagitannins and flavonoids could be due to their ability to scavenge different radicals more or less efficiently, relieving the oxidative stress. Protection conferred by flavonoids, rutin and quercetin 3-O-glucoside to rat liver mitochondria and plasmid pBR322 DNA from radiation induced damage was due to their strong hydroxyl radical scavenging activity. The inhibitory effect of ellagitannins on lipid peroxidation in liver mitochondria was due to their efficient superoxide radical scavenging ability. This is the first report about the radioprotective activity of pure ellagitannins from Phyllanthus amarus.

Hepatoprotective activity of polyherbal formulation (Normeta) in oxidative stress induced by alcohol, polyunsaturated fatty acids and iron in rats

In recent years, oxidative stress has been implicated in the pathophysiology of a large number of diseases or disorders which are initiated and/or exacerbated by pro-oxidants such as various drugs including alcohol and food additives. The present study was carried out to evaluate the effects of oral treatment with polyherbal formulation Normeta (2 ml and 4 ml/kg) on hepatic damage induced by alcohol 10-30% (blood alcohol was maintained at levels between 150 and 350 mg/dl), thermally oxidized oil (polyunsaturated fatty acids) (15% of diet) and carbonyl iron (1.5-2% of diet) for 30 days in rats. In vitro studies with 1, 1-Diphenyl, 2-Picrylhydrazyl (DPPH), Nitric oxide and Ferric chloride (Fe(+3) ions) showed that Normeta possesses antioxidant and metal chelating activity. Alcohol, polyunsaturated fatty acids and iron feeding produced an increase in serum levels of iron, serum glutamate pyruvate transaminase and decrease in serum proteins. It was also associated with elevated lipid peroxidation (thiobarbituric acid reactive substances) and disruption of antioxidant defence mechanism in liver, decreased body weight and increased liver to body weight ratio. Oral administration of Normeta along with alcohol, polyunsaturated fatty acids and iron decreased the serum iron, serum glutamate pyruvate transaminase levels and increased serum protein levels. The levels of liver thiobarbituric acid reactive substances were decreased and the activities of antioxidant enzymes superoxide dismutase and catalase were increased. Improvement in body weight and liver to body weight ratio was also observed. The effects of Normeta on physico-metabolic parameters were comparable with silymarin. This indicates that Normeta has favourable effect in bringing down the severity of hepatotoxicity.

Neuroprotective effects of Withania somnifera dunal.: A possible mechanism

Present study was carried out to understand the possible mechanism of neuroprotective action of the root extract of Withania somnifera Dunal (WS). The study is focused on WS mediated inhibition of nitric oxide production, which is known to mediate neurodegeneration during stress. Adult mice (28 +/- 5 g) were exposed to restraint stress for 30 days. Activity of NADPH diaphorase (NADPH-d) and factors (Acetylcholine, serotonin and corticosterone), which regulates NADPH-d activity were studied. Treatment with WS extract for 30 days during stress, significantly reversed the stress induced NADPH-d activation. Observations suggest that inhibition of NADPH-d by WS is not a direct effect of extract on NADPH-d, instead it inhibits via suppressing corticosterone release and activating cholineacetyltransferase, which in turn increase serotonin level in hippocampus to inhibit NADPH-d. Together, the main mechanism underlying the neuroprotective effects of WS can be attributed to its role in the down regulation of nNOS and neurochemical alterations of specific neurotransmitter systems. These observations thus suggest that WS root extract could be developed as a potential preventive or therapeutic drug for stress induced neurological disorders.

Antibacterial, antifungal, insecticidal, cytotoxicity and phytotoxicity studies on Indigofera gerardiana

The antibacterial, antifungal, acute cytotoxicity, phytotoxicity and insecticidal profile of the crude extract and various fractions of Indigofera gerardiana have been studied. Six bacterial and fungal strains were used, of which Samonella typhi and Microsporum canis were the most susceptible strains with MICs 0.37 mg/mL and 0.09 mg/mL, respectively. The crude extract and the fractions showed low insecticidal activity against Sitophilus oryzae, Rhyzopertha dominica and Callosbruchus analis but no activity against Tribolium castaneum. The brine shrimp lethality assay showed absence of any measurable cytotoxicity of the crude extract and fractions, showing a good safety profile at a preliminary level. All the fractions except crude extract revealed profound and highly significant herbicidal activity against Lemna minor at the concentration of 1000 microg/mL. Indigofera gerardiana was shown by in-vitro assays to be a potential source for natural antifungal, antibacterial and herbicidal agents.

In vitro studies of polyphenol compounds, total antioxidant capacity and other dietary indices in a mixture of plants (Prolipid)

The best health and nutrition results can be achieved not only from the consumption of fruits and vegetables with high antioxidant capacities, but also from medicinal plants and herbs. Therefore, in the present investigation, the bioactive compounds (polyphenols and flavonoids) and the radical scavenging capacities of Prolipid, a mixture of herbs, were studied. Water extracts showed relatively high capacity of about 61.5% inhibition with the beta-carotene linoleic acid assay. In order to support the data obtained with beta-carotene-linoleic acid assay, three different antioxidant assays were used: ferric-reducing/antioxidant power, trolox equivalent antioxidant capacity, and 1,1-diphenyl-2-picrylhydrazyl radical with prolonged time of their reactions. It was found that the amounts of polyphenols in water and methanol extracts were 22.849+/-2.267 and 3.241+/-0.325 mg gallic acid equivalent/g dry weight, and the antioxidant capacities in same extracts as determined by the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) test after 120 min were 275.81+/-27.58 and 62.25+/-6.11 micromole Trolox equivalents (microMTE) g dry weight, respectively. The correlation coefficients between polyphenols and antioxidant capacities of Prolipid with 1,1-diphenyl-2-picrylhydrazyl radical and beta-carotene linoleic acid assay were about 0.97 and 0.98. In conclusion, the bioactivity of Prolipid was high and the total polyphenols were the main contributors to the overall antioxidant capacity. The results of our investigation in vitro are comparable with other medicinal plants and fruits widely used in the treatment of humans without known side effects. Prolipid, a mixture of herbs, can therefore be used as a supplement for nutritional and healthy purposes.