G. Ilavazhagan

Anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides)—an in vitro study

This study was designed to determine the anti-oxidant and immunomodulatory properties of seabuckthorn (Hippophae rhamnoides) using lymphocytes as a model system. Chromium(VI) as potassium dichromate was used to induce oxidative damage. The production of free radicals by chromium and the ability of alcoholic leaf and fruit extracts of seabuckthorn to inhibit the oxidative damage induced by chromium was investigated. Addition of chromium (10 microg/ml) to the cells resulted in enhanced cytotoxicity, apoptosis, free radical production and decreased glutathione (reduced) levels. Chromium also caused a significant inhibition of lymphocyte proliferation induced by both lipopolysaccharide and concanavalin A. Alcoholic extracts of leaves and fruits of seabuckthorn at a concentration of 500 microg/ml were found to inhibit chromium-induced free radical production, apoptosis, DNA fragmentation and restored the anti-oxidant status to that of control cells. In addition, these extracts also were able to arrest the chromium-induced inhibition of lymphocyte proliferation. These observations suggest that the alcoholic extracts of leaves and fruits of seabuckthorn have marked cytoprotective properties, which could be attributed to the anti-oxidant activity.

Neuroprotective effect of N-acetyl cysteine on hypoxia-induced oxidative stress in primary hippocampal culture

Hippocampus has received a considerable attention in the recent past due to its role in a number of important functions such as learning and memory. The effect of hypoxia on neuronal cell injury especially on hippocampal cells is not well known. The aim of the present study was to characterize the biochemical changes in primary cultured hippocampal neurons during hypoxic exposure and the protective effect of N-acetyl cysteine on hypoxia-induced cytotoxicity. The hippocampal culture grown in 24-well plates was exposed to hypoxia for 3 h in a dessicator in 95% N(2), 5% CO(2) atmosphere at 37 degrees C. Later, the cells were allowed to recover for 1 h under normoxia. It was observed that there is an appreciable increase in cytotoxicity in cells exposed to hypoxia. Further, there was a significant decrease in mitochondrial membrane potential and appreciable increase in reactive oxygen species and single-strand DNA breaks in cells exposed to hypoxia compared to control. There is a significant fall in glutathione peroxidase, glutathione reductase, reduced glutathione levels, and nitric oxide in the cells exposed to hypoxia. Significant elevation in the intracellular calcium level in the cells on exposure to hypoxia was observed. Supplementation with NAC (50 microM) resulted in a significant cytoprotection, fall in ROS generation, and higher antioxidant levels similar to that of control cells. NAC also inhibited DNA strand breaks induced by hypoxia. The study indicates that NAC has significant neuroprotective activity during hypoxia in primary hippocampal culture.

Anti-microbial activity of a new vaginal contraceptive NIM-76 from neem oil (Azadirachta indica)

Efficacy of NIM-76, a spermicidal fraction from neem oil, was investigated for its antimicrobial action against certain bacteria, fungi and Polio virus as compared to whole neem oil. The NIM-76 preparation showed stronger anti-microbial activity than the whole neem oil. It inhibited growth of various pathogens tested including Escherichia coli and Kleibsiella pneumoniae which were not affected by the whole neem oil. NIM-76 also exhibited antifungal activity against Candida albicans and antiviral activity against Polio virus replication in vero cell lines. It also protected mice from systemic candidiasis as revealed by enhanced % survival and reduced colony forming units of C. albicans in various tissues. This shows that NIM-76 has a potent broad spectrum anti-microbial activity.

Cytoprotective and antioxidant activity of Rhodiola imbricata against tert-butyl hydroperoxide induced oxidative injury in U-937 human macrophages

The present study reports cytoprotective and antioxidant activity of aqueous and alcoholic extracts of Rhodiolaimbricata rhizome on tert-butyl hydroperoxide (tert-BHP) induced cytotoxicity in U-937 human macrophages. There was an increase in cytotoxicity and apoptosis significantly in the presence of tert-BHP over control cells. The tert-BHP induced cytotoxicity can be attributed to enhanced reactive oxygen species (ROS) production which in turn is responsible for fall in reduced glutathione (GSH) levels; further there was a significant decrease in mitochondrial potential and increase in apoptosis and DNA fragmentation. Both aqueous and alcoholic extracts of Rhodiola rhizome at a concentration of 250 μg/ml were found to inhibit tert-BHP induced free radical production, apoptosis and to restore the anti-oxidant levels to that of the control cells. The alcoholic extract of Rhodiola showed higher cytoprotective activities than aqueous extract. These observations suggest that the alcoholic and aqueous extracts of Rhodiola have marked cytoprotective and antioxidant activities.

Cyto-protective and immunomodulating properties of Amla (Emblica officinalis) on lymphocytes: an in-vitro study

The fruits extracts of Emblica officinalis (Amla) has been reported to have strong anti-oxidant properties. There is a paucity of studies on the immunomodulatory properties of fruit extracts of Amla in immuno-compromised states, with the emphasis on lymphocytes. Therefore, the aim of the study was to determine the anti-oxidant and immunomodulatory properties of Amla using chromium (VI) as an immunosuppressive agent. Chromium (Cr) treatment results in enhanced cytotoxicity, free radical production, lipid peroxidation and decreased glutathione peroxidase (GPx) activity and diminished glutathione (GSH) levels. There was a significant inhibition of both lipopolysaccharide and concanavalin-A-stimulated lymphocyte proliferation. Chromium also inhibited Con A stimulated interleukin-2 and gamma-interferon production significantly. Further, there was enhanced apoptosis and DNA fragmentation in the presence of Cr. Amla significantly inhibited Cr-induced free radical production and restored the anti-oxidant status back to control level. Amla also inhibited apoptosis and DNA fragmentation induced by Cr. Interestingly, Amla relieved the immunosuppressive effects of Cr on lymphocyte proliferation and even restored the IL-2 and gamma-IFN production considerably.

Effect of Kombucha tea on chromate(VI)-induced oxidative stress in albino rats

The effect of Kombucha tea (KT) on oxidative stress induced changes in rats subjected to chromate treatment are reported. KT feeding alone did not show any significant change in malondialdehyde (MDA) and reduced glutathione (GSH) levels, but did enhance humoral response and delayed type of hypersensitivity (DTH) response appreciably over control animals. Chromate treatment significantly enhanced plasma and tissue MDA levels, decreased DTH response considerably, enhanced glutathione peroxidase and catalase activities; however, no change in GSH, superoxide dismutase and antibody titres was noticed. KT feeding completely reversed the chromate-induced changes. These results show that Kombucha tea has potent anti-oxidant and immunopotentiating activities.

Antioxidant activities of seabuckthorn (Hippophae rhamnoides) during hypoxia induced oxidative stress in glial cells.

The present study reports the cytoprotective and antioxidant properties of alcoholic leaf extract of seabuckthorn (SBT) against hypoxia induced oxidative stress in C-6 glioma cells. Exposure of cells to hypoxia for 12 h resulted in a significant increase in cytotoxicity and decrease in mitochondrial transmembrane potential compared to the controls. Further an appreciable increase in nitric oxide and reactive oxygen species (ROS) production was noted which in turn was responsible for fall in intracellular antioxidant levels and GSH/GSSG ratio. There was a significant increase in DNA damage during hypoxia as revealed by comet assay. Pretreatment of cells with alcoholic leaf extract of SBT at 200 μg/ml significantly inhibited cytotoxicity, ROS production and maintained antioxidant levels similar to that of control cells. Further, the leaf extract restored the mitochondrial integrity and prevented the DNA damage induced by hypoxia. These results indicate that the leaf extract of SBT has strong antioxidant and cytoprotective activity against hypoxia induced oxidative injury. (Mol Cell Biochem 278: 9–14, 2005)

ACETYL-L-CARNITINE (ALCAR) PREVENTS HYPOBARIC HYPOXIA-INDUCED SPATIAL MEMORY IMPAIRMENT THROUGH EXTRACELLULAR RELATED KINASE-MEDIATED NUCLEAR FACTOR ERYTHROID 2-RELATED FACTOR 2 PHOSPHORYLATION

Exposure to hypobaric hypoxia, a condition involving decreased availability of oxygen is known to be associated with oxidative stress, neurodegeneration and memory impairment. The multifactorial response of the brain and the complex signaling pathways involved therewith limits the therapeutic efficacy of several antioxidants in ameliorating hypobaric hypoxia-induced memory impairment. The present study was therefore aimed at investigating the potential of acetyl-l-carnitine (ALCAR), a known antioxidant that has been reported to augment neurotrophin-mediated survival mechanisms, in ameliorating hypoxia-induced neurodegeneration and memory impairment. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor involved in the cellular defense mechanism against oxidative stress related to brain injury and neurological disorders. The study was designed to understand the mechanisms involving Nrf2 stabilization following exposure to hypobaric hypoxia. The results displayed reference memory impairment in Sprague-Dawley rats exposed to hypobaric hypoxia (7620 m) for 14 consecutive days which however improved on administration of ALCAR during hypoxic exposure. The study also revealed Nrf2 regulated augmented antioxidant response on administration of ALCAR which was through a novel tyrosine kinase A (TrkA) receptor-mediated mechanism. A decrease in free radical generation, lipid peroxidation and protein oxidation was also observed along with a concomitant increase in thioredoxin and reduced glutathione levels on administration of ALCAR during exposure to hypobaric hypoxia. The present study therefore reveals the therapeutic potential of ALCAR under conditions of hypobaric hypoxia and elucidates a novel mechanism of action of the drug.

Antioxidant effect of beta-carotene on hypoxia induced oxidative stress in male albino rats.

Hypoxia is known to induce oxidative stress in organisms leading to tissue injury. In the present study beta-carotene (BC) given at 10 mg/kg body weight (BW) in reducing the oxidative stress induced by hypoxia was evaluated on male albino rats. Hypoxia exposure caused an increase in malondialdehyde (MDA) levels in plasma and tissues, a concurrent decrease in blood glutathione (GSH), glutathione peroxidase (GPx), plasma protein and plasma BC content. Hemoglobin concentration, Red blood corpuscles (RBC) and White blood corpuscles (WBC) count were also increased under hypoxia. BC supplementation reversed the trend, inducing a significant decrease (P<0.05) in MDA and subsequent increase in plasma and tissue GSH levels in animals exposed to hypoxia. Blood GPx and plasma protein also increased significantly in BC supplemented animals. BC supplementation did not alter the changes in Hb concentration, RBC and WBC count. BC has potent antioxidant activities in reducing the oxidative stress induced by hypobaric hypoxia.

Immunomodulatory effects of seabuckthorn (Hippophae rhamnoides L.) against chromium (VI) induced immunosuppression.

The present study reports the immunomodulatory effects of seabuckthorn (Hippophae rhamnoides L.) leaf extract on cellular and humoral immune response by studying delayed-type hypersensitivity response, IL-2, IL-4 and γ-IFN levels and antibody titres in chromium-induced immunosuppressed animals. Oral feeding of chromium (30 mg/kg bw) significantly inhibited antibody production and S-RBC induced delayed-type hypersensitivity response. Administration of leaf extract (100 mg/kg bw) along with chromium significantly inhibited chromium-induced immunosuppression. To understand the immunomodulatory mechanism of leaf extract, in vitro studies were carried out using rat lymphocytes. Addition of chromium resulted in a significant decrease in lymphocyte size and increased ROS generation. The leaf extract of seabuckthorn significantly inhibited chromium-induced reactive oxygen species (ROS) generation and maintained the cell size identical to that of control cells. Chromium treatment markedly inhibited the mitochondrial transmembrane potential by larger lymphocytes in particular, while the leaf extract restored the same significantly. Chromium also inhibited significantly concanavalin A (ConA) induced IL-2, IL-4 and γ-IFN production in rat lymphocytes. The leaf extract (100 μg/ml) alone stimulated IL-2 and γ-IFN production even in the absence of ConA and also inhibited chromium-induced decline in IL-2 and γ-IFN production but it did not change IL-4 production. These observations suggest that the leaf extract of seabuckthorn has significant immunomodulatory activity and specifically activates the cell-mediated immune response. (Mol Cell Biochem 278: 101–109, 2005)