P. Rani

Bio: P. Rani is an academic researcher from PSG College of Technology. The author has contributed to research in topics: Glutathione peroxidase & Antioxidant. The author has an hindex of 8, co-authored 10 publications receiving 303 citations. Previous affiliations of P. Rani include Indian Institute of Technology Madras.

Enzymatic and non-enzymatic antioxidants in selected Piper species.

Abstract: Piper species, commonly used in diet and traditional medicine were assessed for their antioxidant potential. Catalase activity was predominated in Piper longum, followed by Piper cubeba, green pepper, Piper brachystachyum and Piper nigrum. P. nigrum was richest in glutathione peroxidase and glucose-6-phosphate dehydrogenase, green pepper was richest in peroxidase and vitamin C while vitamin E was more in P. longum and P. nigrum. P. brachystachyum and P. longum were rich sources of vitamin A. All the Piper species had GSH content of around 1 to 2 nM/g tissue. The antioxidant components of Piper species constitute a very efficient system in scavenging a wide variety of reactive oxygen species. Antioxidant potential of Piper species was further confirmed by their ability to curtail in vitro lipid peroxidation by around 30-50% with concomitant increase in GSH content.

Evaluation of antioxidant properties of berries

Abstract: The present paper focuses on assessing the levels of various enzymatic and non-enzymatic antioxidants in selected berries of Indian sub-continent viz., gooseberry, grapes, orange and tomato. This study has revealed that orange, tomato and grapes possess predominant quantities of enzymatic antioxidants namely SOD, catalase and glutathione peroxidase respectively. The levels of antioxidants analyzed namely reduced glutathione, vitamin C and vitamin A were maximal in grapes, orange and tomato respectively. All the extracts of berries included in the present study inhibited iron inducedin vitro lipid peroxidation in erythrocytes, the extend of inhibition being highest for gooseberry and orange compared to tomato and grapes which could be attributed to their in-built antioxidant system.

Evaluation of selenium, redox status and their association with plasma amyloid/tau in Alzheimer's disease.

Abstract: The aim of the study was to evaluate blood selenium and antioxidants as possible oxidative stress markers in Alzheimer’s disease (AD) along with amyloid β42 (Aβ42) and tau by comparing them with vascular dementia (VD) and age-matched healthy controls. Selenium, total tau, Aβ42, glutathione (GSH) and malondialdehyde (MDA) levels and the activities of antioxidant enzymes were analysed in the blood of AD patients (n = 30), VD patients (n = 35) and controls (n = 40) from South India. Plasma Aβ42 level was significantly higher (P < 0.001) in both AD and VD compared to controls. Total tau and tau-to-amyloid ratio were significantly lower in both AD and VD (P < 0.001), compared to controls, and a significant difference (P < 0.01 and P < 0.05, respectively) was also observed between AD and VD. The receiver operating characteristic (ROC) curve-derived cutoff values of <3.5 for tau-to-Aβ42 ratio and <520 pg/ml for total tau showed sensitivity and specificity of around 67–72 % for differentiating AD from VD and around 90 % for AD from controls, indicating that they could serve as reliable AD-specific markers. The MDA levels were significantly higher (P < 0.001) in both dementia groups along with a significant decrease (P < 0.001) in reduced GSH levels, indicating elevated oxidative stress and altered redox status in both forms of dementia. Selenium levels did not vary significantly between the three groups. The activity of glutathione peroxidase increased in both AD and VD compared to controls, with a concomitant decrease in glutathione reductase and glucose-6-phospate dehydrogenase (P < 0.001) activity. The activity of thioredoxin reductase was significantly lower in both patient groups (P < 0.001) compared to healthy controls. No correlation was observed between selenium and activities of selenoenzymes, tau, Aβ42 or tau-to-Aβ42 ratio, when analysing independently, indicating that blood selenium may not be directly involved in Aβ production and in regulating tau/Aβ42-mediated mechanism in AD. The present study emphasizes the enhanced oxidative stress in AD pathology and plasma tau and tau-to-amyloid ratio as possible markers to differentiate AD from VD. The study also points that blood selenium may not be involved in regulating oxidative stress in AD, and a longitudinal study correlating plasma and cerebrospinal fluid (CSF) selenium and selenoprotein levels is warranted.

Evaluation of Lignocellulosic Wastes for Production of Edible Mushrooms

Abstract: The degradation of lignocellulosic wastes such as paddy straw, sorghum stalk, and banana pseudostem was investigated during solid-state fermentation by edible mushrooms Pleurotus eous and Lentinus connotus. Biological efficiency of 55-65% was observed in paddy straw followed by sorghum stalk (45%) and banana pseudostem (33%) for both fungal species. The activity of extracellular enzymes, namely cellulase, polyphenol oxidase, and laccase, together with the content of cellulose, lignin, and phenols, was studied in spent substrates on seventh, 17th, and 27th days of spawning, and these values were used as indicators of the extent of lignocellulosic degradation by mushroom. Both the mushroom species proved to be efficient degraders of lignocellulosic biomass of paddy straw and sorghum stalk, and the extent of cellulose degradation was 63-72% of dry weight (d.w.), and lignin degradation was 23-30% of the d.w. In banana pseudostem, the extent of the degradation was observed to be only 15-22% of the d.w. for both lignin and cellulose. Preferential removal of cellulose during initial growth period and delayed degradation of lignin were observed in all three substrates. This is associated with decrease in activity of cellulase and polyphenol oxidase and increase in laccase activity with spawn aging in spent substrates. Thus, bioconversion of lignocellulosic biomass by P. eous and L. connotus offers a promising way to convert low-quality biomass into an improved human food.

Study on Analysis of Peripheral Biomarkers for Alzheimer's Disease Diagnosis.

Abstract: Many factors are involved in Alzheimer’s disease (AD) pathology including tau phosphorylation, amyloid β protein (Aβ) accumulation, lipid dysregulation, oxidative stress and inflammation. The markers of these pathological processes in cerebral spinal fluid CSF are used currently for AD diagnosis. However peripheral biomarkers are the need of the hour for large population screening for AD. The main objective of the present study is to evaluate the peripheral levels of redox markers, lipid peroxidation indicators and pathological markers in AD patients. Blood was collected from AD patients (n=45), controls (n=45) and analyzed for pathological markers of AD including Aβ42 and tau, lipid peroxidation and redox indicators. Plasma Aβ42 was significantly (P<0.001) elevated while total tau was decreased in AD compared to controls. Hydroxynonenal (HNE) and Malondialdehyde (MDA), were higher (P<0.001) in AD patients pointing the enhanced lipid peroxidation in AD pathology. Receiver operating characteristic curve (ROC) analysis indicated that HNE is a better indicator of lipid peroxidation compared to MDA. Plasma glutathione (GSH) level was significantly (P<0.001) low while oxidized glutathione (GSSG) level was higher (P<0.001) in AD patients with corresponding decrease in GSH/GSSG ratio (P<0.001). ROC analysis indicated that GSH/GSSG ratio can be used as reliable indicator for redox imbalance in AD with a cutoff value of <8.73 (Sensitivity 91.1%, Specificity 97.8%). Correlation analysis revealed a positive correlation for both HNE and MDA with Aβ42 and a negative correlation with total tau. Negative correlation was observed between GSH/GSSG ratio and lipid peroxidation markers. While oxidative stress has been implicated in pathology of various neurodegenerative disorders, the present study pinpoints the direct link between lipid peroxidation and Aβ production in plasma of AD patients. Normally at low amyloid concentration in body fluids, this peptide shown to function as a strong metal chelating antioxidant. However when the Aβ production enhanced as in AD, through gain of functional transformation, Aβ evolves into prooxidant thereby enhancing oxidative stress and LPO. Altered redox status with enhanced lipid peroxidation observed in AD blood could contribute to the oxidation and S –Glutathionylation proteins which has to be addressed in future studies.

Amyloid β-Peptide (1–42)-Induced Oxidative Stress in Alzheimer Disease: Importance in Disease Pathogenesis and Progression

Abstract: Significance: Alzheimer disease (AD) is an age-related neurodegenerative disease. AD is characterized by progressive cognitive impairment. One of the main histopathological hallmarks of AD brain is the presence of senile plaques (SPs) and another is elevated oxidative stress. The main component of SPs is amyloid beta-peptide (Aβ) that is derived from the proteolytic cleavage of amyloid precursor protein. Recent Advances: Recent studies are consistent with the notion that methionine present at 35 position of Aβ is critical to Aβ-induced oxidative stress and neurotoxicity. Further, we also discuss the signatures of oxidatively modified brain proteins, identified using redox proteomics approaches, during the progression of AD. Critical Issues: The exact relationships of the specifically oxidatively modified proteins in AD pathogenesis require additional investigation. Future Directions: Further studies are needed to address whether the therapies directed toward brain oxidative stress and oxidatively...

Cultivation of Pleurotus ostreatus and other edible mushrooms

Abstract: Pleurotus ostreatus is the second most cultivated edible mushroom worldwide after Agaricus bisporus. It has economic and ecological values and medicinal properties. Mushroom culture has moved toward diversification with the production of other mushrooms. Edible mushrooms are able to colonize and degrade a large variety of lignocellulosic substrates and other wastes which are produced primarily through the activities of the agricultural, forest, and food-processing industries. Particularly, P. ostreatus requires a shorter growth time in comparison to other edible mushrooms. The substrate used for their cultivation does not require sterilization, only pasteurization, which is less expensive. Growing oyster mushrooms convert a high percentage of the substrate to fruiting bodies, increasing profitability. P. ostreatus demands few environmental controls, and their fruiting bodies are not often attacked by diseases and pests, and they can be cultivated in a simple and cheap way. All this makes P. ostreatus cultivation an excellent alternative for production of mushrooms when compared to other mushrooms.