Scavenging of free-radicals and inhibition of lipid peroxidation by 3-phenylsydnone

Hepatoprotective activity of Phyllanthus niruri Linn. endophytes

Background

The liver is the vital organ which plays a major role in metabolism with numerous functions in the human beings such as protein synthesis, hormone production, and detoxification. Present research work is focused on hepatoprotective potential of chloroform (PNFC) and ethyl acetate (PNFEA) endophytic fractions from Phyllanthus niruri Linn. against CCl4-induced hepatotoxicity in albino Wistar rats. To test our hypothesis, both endophytic fungal fractions were tested for vitro antioxidant and in vivo hepatoprotective activity. Serum biochemical parameters like SGOT, SGOT, SALP, cholesterol, bilirubin, and protein were estimated to assess hepatoprotective activity.

Results

Group of rats treated with CCl4 possess marked hepatic damage and oxidative stress which indicates that cellular leakage and loss of functional integrity of cell membrane in liver. PNFC and PNFEA fractions of endophyte from Phyllanthus niruri Linn. stem have significantly reduced the elevated levels of biomarkers like SGPT, SGOT, SALP, bilirubin, cholesterol, and total protein in CCl4-induced hepatotoxicity in rats. The results obtained confirm hepatoprotective activity of endophytic fractions (PNFC and PNFEA) mediated through the stabilization of plasma membrane, repair of hepatic tissue damage, return of biochemical marker levels to normal, and regeneration of hepatocytes. Histopathological observations revealed improvement in the liver architecture after the treatment of secondary metabolites of endophytic fractions against CCl4-induced liver damage. Both fungal endophytes PNFC and PNFEA showed DPPH scavenging activity with IC50 of 97.79 μg/ml and 108.40 μg/ml, respectively, and possess antioxidant potential. Presence of flavonoids in the both fractions of endophytes may be a possible reason for its antioxidant potential and identified as Eurotium amstelodami strain.

Conclusion

Both fungal endophytes PNFC and PNFEA possess hepatoprotective potential due to the presence of secondary metabolites of fungi, i.e., Eurotiumam stelodami strain which support the claim endophytes and act as a potent biomedicine for treatment of various chronic diseases.

Polyphenolic enriched extract of Cassia glauca Lamk, improves streptozotocin-induced type-1 diabetes linked with partial insulin resistance in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Traditionally Cassia glauca (CG) has been used to treat diabetes.

AIM OF THE STUDY

The study was undertaken to evaluate anti-diabetic and antioxidant activity of polyphenolic enriched extract of CG in standardized streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

The effect of ethanol (CGE) and water (CGW) extracts of CG (200 and 400mg/kg) treatment were evaluated in STZ (50mg/kg, iv) induced diabetic rats. On 10^th day, oral glucose tolerance test and degree of insulin resistance was calculated. On 13^th day, insulin tolerance test was performed to know the peripheral utilization of glucose. On 15^th day, blood glucose, lipid profiles and endogenous antioxidant levels were estimated. In addition, the effects on oral glucose/sucrose tolerance test in normal rats. Further, HPLC fingerprinting profile of CGE and simultaneous quantification of biomarkers were carried out.

RESULTS

Supplementation with CGE and CGW significantly reduced STZ-induced deleterious effects and improved glucose tolerance, and insulin tolerance. In addition, supplementation also decreased oxidative stress by improving endogenous antioxidant levels. Furthermore, administration significantly improves sucrose tolerance suggesting that extract possess inhibition of α-glucosidase enzyme. Further, HPLC studies revealed that CGE contains three bioactive polyphenolic compounds viz., rutin (0.10±0.01mg/g), luteolin-7-glucoside (0.06±0.01mg/g) and isorhoifolin (0.7±0.05mg/g).

CONCLUSION

Observed beneficial outcome of CG might be attributed to the presence of polyphenolic compounds and mediated by interacting with multiple targets of diabetes and oxidative stress. Taken together, this study provided the scientific evidence for the traditional use of CG.

Development and evaluation of sunscreen creams containing morin-encapsulated nanoparticles for enhanced UV radiation protection and antioxidant activity

The objective of present work was to develop novel sunscreen creams containing polymeric nanoparticles (NPs) of morin. Polymeric NPs containing morin were prepared and optimized. The creams containing morin NPs were also prepared and evaluated. Optimized NPs exhibited particle size of 90.6 nm and zeta potential of −31 mV. The entrapment efficiency of morin, within the polymeric NPs, was found to be low (12.27%). Fourier transformed infrared spectroscopy and differential scanning calorimetry studies revealed no interaction between morin and excipients. Transmission electron microscopy and atomic force microscopy revealed that the NPs were spherical in shape with approximately 100 nm diameter. Optimized NPs showed excellent in vitro free radical scavenging activity. Skin permeation and deposition of morin from its NPs was higher than its plain form. Different sunscreen creams (SC1–SC8) were formulated by incorporating morin NPs along with nano zinc oxide and nano titanium dioxide. SC5 and SC8 creams showed excellent sun protection factor values (≈40). In vitro and in vivo skin permeation studies of sunscreen creams containing morin NPs indicated excellent deposition of morin within the skin. Morin NPs and optimized cream formulations (SC5 and SC8) did not exhibit cytotoxicity in Vero and HaCaT cells. Optimized sunscreen creams showed excellent dermal safety. SC5 and SC8 creams demonstrated exceptional in vivo antioxidant effect (estimation of catalase, superoxide dismutase, and glutathione) in UV radiation-exposed rats. The optimized sunscreen creams confirmed outstanding UV radiation protection as well as antioxidant properties.

Ficus racemosa Stem Bark Extract: A Potent Antioxidant and a Probable Natural Radioprotector

Ethanol extract (FRE) and water extract (FRW) of Ficus racemosa (family: Moraceae) were subjected to free radical scavenging both by steady state and time resolved methods such as nanosecond pulse radiolysis and stopped-flow spectrophotometric analyses. FRE exhibited significantly higher steady state antioxidant activity than FRW. FRE exhibited concentration dependent DPPH, ABTS^•−, hydroxyl radical and superoxide radical scavenging and inhibition of lipid peroxidation with IC₅₀ comparable with tested standard compounds. In vitro radioprotective potential of FRE was studied using micronucleus assay in irradiated Chinese hamster lung fibroblast cells (V79). Pretreatment with different doses of FRE 1h prior to 2 Gy γ-radiation resulted in a significant (P < 0.001) decrease in the percentage of micronucleated binuclear V79 cells. Maximum radioprotection was observed at 20 μg/ml of FRE. The radioprotection was found to be significant (P < 0.01) when cells were treated with optimum dose of FRE (20 μg/ml) 1 h prior to 0.5, 1, 2, 3 and 4 Gy γ-irradiation compared to the respective radiation controls. The cytokinesis-block proliferative index indicated that FRE does not alter radiation induced cell cycle delay. Based on all these results we conclude that the ethanol extract of F. racemosa acts as a potent antioxidant and a probable radioprotector.

Antioxidant and radioprotective effect of the active fraction of Pilea microphylla (L.) ethanolic extract

The ethanolic extract of Pilea microphylla (L.) was defatted, successively fractionated with acetone and the residue so obtained was found to be most potent when subjected to detailed free radical scavenging and in vivo radioprotection studies. The most active fraction reacts with free radicals, such as DPPH (50 microM), ABTS(.)(-) (100 microM) and (.)OH (generated by Fenton reaction) with IC(50) value of 23.15 microg/ml, 3.0 microg/ml and 310 microg/ml, respectively. The most active fraction inhibited iron-induced lipid peroxidation in phosphatidyl choline liposomes with an IC(50) of 13.74 microg/ml. The kinetics of scavenging of DPPH and ABTS(.)(-) radicals were followed at different concentrations of the fraction by employing stopped-flow studies. The observed first order decay rate constants at 200 microg/ml and 50 microg/ml of fraction with DPPH (50 microM) and ABTS(.)(-) (50 microM) were found to be 0.4s(-1) and 2.1s(-1), respectively. The fraction when screened for in vivo radioprotection in Swiss albino mice showed 80% protection at a dose of 900 mg/kg and with a DRF of about 1.12. The fraction was also found to protect livers of irradiated mice from depletion of endogenous antioxidant enzymes like glutathione, GST, SOD, catalase and thiols. The fraction also protected the villi height, increased the number of crypt cells while offering general protection to the intestine from acute radiation effects. The fraction also protected the hematopoietic system as assessed by endogenous spleen colony assay, contributing to the overall radioprotective ability.

Identification and evaluation of antioxidant, analgesic/anti-inflammatory activity of the most active ninhydrin–phenol adducts synthesized

Treatment of phenols with ninhydrin in acidic medium afforded 2-hydroxy-2-(ortho-hydroxy-phenyl/naphthyl)-1,3-dioxoindanes, which being unstable were isolated in their hemiketal forms. These synthesized compounds were subjected to TLC screening for radical scavenging and in vitro lipoxgenase and cycloxygenase enzyme inhibition assays. The best compound was identified and studied in detail for steady-state and time-resolved free radical kinetics, viz., DPPH, ABTS(-), *OH and rate constants for these reactions were evaluated. The best compound was also subjected to in vivo anti-inflammatory and analgesic activities in which the compound showed good promise for further structural optimization.

Bioactivity-guided fractionation of Coronopus didymus: A free radical scavenging perspective

The whole plant aqueous extract of Coronopus didymus Linn. was fractionated on the basis of polarity and resulting fractions were evaluated for free radical scavenging ability. The most non-polar fraction (CDF1) was found to be more active than other fractions in scavenging DPPH, ABTS(-), nitric oxide and hydroxyl radicals in steady-state conditions. Stop-flow spectrometric studies showed 58.13% inhibition of 100 microM DPPH at a concentration of 150 microg/ml of CDF1 in 1000 s and 32.31% scavenging of 960 microM ABTS(-) at a concentration of 300 microg/ml of CDF1 in 100 s. The reaction of CDF1 with hydroxyl radicals produced by pulse radiolysis showed a transient spectrum with absorption peaks at 320, 390 and 400 nm, indicating the presence of flavonoids/related components. Competition kinetics with potassium thiocyanate against scavenging of hydroxyl radicals showed a reactivity of 0.1326 against thiocyanate. CDF1 also protected against Fenton reagent-induced calf thymus DNA damage at a concentration of 400 mg/ml indicating it to be the most potent fraction.

Chemical and biochemical properties of casein-sugar Maillard reaction products

The Maillard reaction (MR) involves the condensation reaction between amino acids or proteins with reducing sugars, which occurs commonly in food processing and storage. The Maillard reaction of Glc-, Fru- and Rib-casein was generated at 55 degrees C, pH 7.0 for up to 28 days. The browning and fluorescence of Glc- and Fru-casein increased with increasing heating time. The temporal development of browning and fluorescence of Rib-casein was relatively faster than Glc- and Fru-casein, respectively. Glc-, Fru- and Rib-casein all exhibited antioxidant activity against Fenton reactant-induced hydroxyl free radicals, while only Rib-casein exhibited a weak DPPH free radical scavenging in addition to preventing Fenton reactant-induced oxidation. It was suggested that casein-sugar MRPs work more efficiently to quench hydrophilic than hydrophobic radicals. All three MRPs showed no toxicity to Caco-2 cell at both low and high concentrations. There was no correlation between the browning and/or fluorescence temporal patterns and biochemical activity of the different sugar-casein generated MRPs.

A reliable procedure for comparison of antioxidants in rat brain homogenates

Lipid peroxidation is a major consequence of oxidative stress and an important cause of neuronal damage in ischaemic injuries and neurodegenerative disorders such as Parkinson's disease. Recent research has focused on the development of antioxidant drugs which may delay or minimize neurodegeneration. Rapid and reliable assays are therefore necessary in order to evaluate novel antioxidant compounds. A widely adopted method for measurement of lipid peroxidation is the thiobarbituric acid reacting substances (TBARS) assay. Several variations of this method have appeared in the literature, some of which have been tested by us without success. We have therefore established a reliable procedure which takes into account the most important factors previously found to influence the TBARS method. Briefly, various concentrations of drug were added to rat brain homogenates (10% w/v in 20 mM Tris-HCl buffer, pH 7.4) and incubated at 37 degrees C for 10 min before addition of ammonium ferric sulphate (100 or 1000 microM) and a further incubation at 37 degrees C for 30 min. Proteins were then precipitated with 8.1% sodium dodecyl sulphate, the reaction stopped with 20% acetic acid, and the samples were then centrifuged for 15 min. Aliquots of supernatant were added to an equal volume of thiobarbituric acid (0.8%), samples were heated at 95 degrees C for 30 min, and then cooled on ice before reading at 532 nm. The present adaptation represents a simple and highly reproducible assay which does not require difficult extraction procedures with hazardous chemicals and results in a stable chromagen. The method has been evaluated using a number of structurally distinct antioxidants and iron chelators. IC50 values (microM) for percentage inhibition of TBARS formation were as follows: desferroxamine (1.1), U83836E (1.7), butylated hydroxytoluene (13), U74500A (20), LY231617 (22), idebenone (89), and Trolox (110). This order of potency was comparable to that found with a commercially available, but expensive kit designed to specifically measure malondialdehyde (Spearman's rank correlation coefficient, p < 0.01).