The effects of tocotrienols on murine liver cell viability and their apoptotic events were studied over a dose range of 0-32 microg mL(-1). Normal murine liver cells (BNL CL.2) and murine liver cancer cells (BNL 1ME A.7R.1) were treated with tocotrienols (T(3)), alpha tocopherol (alpha-T) and the chemo drug, Doxorubicin (Doxo, as a positive control). Cell viability assay showed that T(3) significantly (P < or = 0.05) lowered the percentage of BNL 1ME A.7R.1 cell viability in a dose-responsive manner (8-16 microg mL(-1)), whereas T did not show any significant (P>0.05) inhibition in cell viability with increasing treatment doses of 0-16 microg mL(-1). The IC(50) for tocotrienols were 9.8, 8.9, 8.1, 9.7, 8.1 and 9.3 microg mL(-1) at 12, 24, 36, 48, 60 and 72 hours respectively. Early apoptosis was detected 6 hours following T(3) treatment of BNL 1ME A.7R.1 liver cancer cells, using Annexin V-FITC fluorescence microscopy assay for apoptosis, but none were observed for the non-treated liver cancer cells at the average IC(50) of 8.98 microg mL(-1) tocotrienols for liver cancer cells. Several apoptotic bodies were detected in BNL 1ME A.7R.1 liver cancer cells at 6 hours post-treatment with tocotrienols (8.98 microg mL(-1)) using Acridine Orange/Propidium Iodide fluorescence assay. However, only a couple of apoptotic bodies were seen in the non-treated liver cancer cells and the BNL CL.2 normal liver cells. Some mitotic bodies were also observed in the T(3)-treated BNL 1ME A.7R.1 liver cancer cells but were not seen in the untreated BNL 1ME A.7R.1 cells and the BNL CL.2 liver cells. Following T(3)-treatment (8.98 microg mL(-1)) of the BNL 1ME A.7R.1 liver cancer cells, 24.62%, 25.53% and 44.90% of the cells showed elevated active caspase 3 activity at 9, 12 and 24 hours treatment period, respectively. DNA laddering studies indicated DNA fragmentation occurred in the T(3)-treated liver cancer cells, BNL 1ME A.7R.1 but not in non-treated liver cancer cells and the T(3)-treated and non-treated normal liver cells. These results suggest that tocotrienols were able to reduce the cell viability in the murine liver cancer cells at a dose of 8-32 microg mL(-1) and that this decrease in percentage cell viability may be due to apoptosis.
Rats exposed to stress developed various changes in the gastrointestinal tract and hormones. The present study was designed to compare the impact of tocopherol and tocotrienol on changes that influence gastric and hormonal parameters important in maintaining gastric mucosal integrity in rats exposed to restrain stress. These include gastric acidity, gastric tissue content of parameters such as malondialdehyde, prostaglandin (PGE(2)), serum levels of gastrin and glucagon-like peptide-1 (GLP-1). Sixty male Sprague-Dawley rats (200-250 g) were randomly divided into three equal sized groups, a control group which received a normal rat diet (RC) and two treatment groups each receiving a vitamin deficient diet with oral supplementation of either tocopherol (TF) or tocotrienol (TT) at 60 mg/kg body weight. Blood samples were taken from half the number of rats (non-stressed group) after a treatment period of 28 days before they were killed. The remaining half was subjected to experimental restraint-stress, at 2 hours daily for 4 consecutive days (stressed groups), on the fourth day, blood samples were taken and the rats killed. The findings showed that the gastric acid concentration and serum gastrin level in stressed rats were significantly (P<0.05) reduced compared to the non-stressed rats in the control and TF groups. However, the gastric acidity and gastrin levels in the TT group were comparable in stressed and non-stressed rats. These findings suggest that tocotrienol is able to preserve the gastric acidity and serum gastrin level which are usually altered in stressed conditions. The PGE(2) content and the plasma GLP-1 level were, however, comparable in all stressed and non-stressed groups indicating that these parameters were not altered in stress and that supplementation with TF or TT had no effect on the gastric PGE2 content or the GLP-1 level. The malondialdehyde, an indicator of lipid peroxidation was higher from gastric tissues in the stressed groups compared to the non-stressed groups. These findings implicated that free radicals may play a role in the development of gastric injury in stress and supplementation with either TF or TT was able to reduce the lipid peroxidation levels compared to the control rats. We conclude that both tocopherol and tocotrienol are comparable in their gastro-protective ability against damage by free radicals generated in stress conditions, but only tocotrienol has the ability to block the stress-induced changes in the gastric acidity and gastrin level.
Antioxidants are important inhibitory compounds against the oxidative deterioration of food. This study investigated the effects of various phytochemical antioxidant systems [oleoresin rosemary (OR), oleoresin sage (OS) and citric acid (CA)] on the physico-chemical characteristics of refined, bleached and deodorized (RBD) palm olein during the frying of potato chips. The effects of various mixtures of the antioxidants on the oil was also studied in repeated deep frying. The response surface methodology was used to optimize the composition of mixed antioxidants used. A comparative study was carried out with synthetic antioxidants. Samples of the oil after frying were analyzed for different physical and chemical properties. OR and OS were found to be effective phytochemical antioxidants protecting RBD palm olein against oxidative deterioration during frying.
Nine derivatives of three natural diarylheptanoids, curcumin, demethoxycurcumin and bisdemethoxycurcumin, were prepared. Their antioxidant, free radical scavenging, nitric oxide (NO) inhibitory and cytotoxic activities were evaluated and compared with those of the respective natural compounds. Curcumin (1), demethoxycurcumin (2), demethyldemethoxy-curcumin (C3), diacetyldemethoxycurcumin (AC2) and triacetyldemethylcurcumin (AC5) exhibited higher antioxidant activity than quercetin while products from demethylation of 1 and 2 exhibited higher free radical scavenging activity. Compounds AC2 and AC5 were found to be most active in inhibiting breast cancer cells (MCF-7) proliferation with IC50 values of 6.7 and 3.6 microM, respectively. The activity of AC2 is almost doubled and of AC5 almost tripled as compared to curcumin. Their selectivity towards different cell lines is also more noticeable. Compounds AC2 and AC5 also showed increased activity against a human prostate cancer cell line (DU-145) and non-small lung cancer cell line (NCI-H460) with IC50 values of 20.4, 16.3 and 18.3, 10.7 microM, respectively.
The present study was performed to evaluate the wound healing and antioxidant effect of aqueous extract of Ocimum sanctum Linn. (O. sanctum) in rats. Albino rats of either sex were divided into 2 groups. Group I: Wounded control rats; Group II: Wounded rats administered O. sanctum aqueous extract. Wound breaking strength in incision wound model, epithelization period and percent wound contraction in excision wound model were studied. Using dead space wound model, granulation tissue breaking strength, granulation tissue dry weight, hydoxyproline level in dry granulation tissue, superoxide dismutase (SOD) and catalase levels in wet granulation tissue were estimated in both the groups. Increased wound breaking strength, decreased epithelization period, increased percent wound contraction, increased granulation tissue weight and hydroxyproline concentrations were observed. The increased activity of antioxidant enzymes such as SOD, catalase level in extract treated group compared to controls. Granulation tissue was subjected to histopathological examination to determine the pattern of lay-down for collagen using Haematoxylin and Eosin stains which confirm the results. Owing to wound healing and antioxidant activities, O. sanctum may be useful in the management of abnormal healing such as keloids and hypertrophic scars.
Garlic and garlic extracts, through their antioxidant activities, have been reported to provide protection against free radical damage in the body. This study investigated antioxidant properties of garlic compounds representing the four main chemical classes, alliin, allyl cysteine, allyl disulfide, and allicin, prepared by chemical synthesis or purification. Alliin scavenged superoxide, while allyl cysteine and allyl disulfide did not react with superoxide. Allicin suppressed the formation of superoxide by the xanthine/xanthine oxidase system, probably via a thiol exchange mechanism. Alliin, allyl cysteine, and allyl disulfide all scavenged hydroxyl radicals; the rate constants calculated based on deoxyribose competitive assay were 1.4-1.7 x 10(10), 2.1-2.2 x 10(9), and 0.7-1.5 x 10(10) M (1) second(1), respectively. Contrary to previous reports, allicin did not exhibit hydroxyl radical scavenging activity in this study. Alliin, allicin, and allyl cysteine did not prevent induced microsomal lipid peroxidation, but both alliin and allyl cysteine were hydroxyl scavengers, and allyl disulfide was a lipid peroxidation terminator. In summary, our findings indicated that allyl disulfide, alliin, allicin, and allyl cysteine exhibit different patterns of antioxidant activities as protective compounds against free radical damage.
Probucol is a clinically used cholesterol-lowering drug, with pronounced antioxidant properties. We have reported previously, that dietary supplementation of probucol enhances NAD(P)H:quinone reductase (Iqbal M, Okada S (2003) Pharmacol Toxicol 93:259-263) and inhibits Fe-NTA induced lipid peroxidation and DNA damage in vitro (Iqbal M, Sharma SD, Oakada (2004) Redox Rep 9:167-172). Further to this, in the present study, we evaluated the modulatory effect of probucol on iron nitrilotriacetae (Fe-NTA) dependent renal carcinogenesis, hyperproliferative response and oxidative stress. In Fe-NTA alone treated group, a 20% renal cell tumor incidence was recorded whereas, in N-diethylnitrosamine (DEN)-initiated and Fe-NTA promoted animals, the percentage tumor incidence was increased to 70% as compared with untreated controls. No tumor incidence was recorded in DEN-initiated, nonpromoted group. Diet supplemented with 1.0% probucol fed prior to, during and after Fe-NTA treatment in DEN-initiated animals afforded >65% protection in renal cell tumor incidence. Probucol fed diet pretreatment also resulted a significant and dose dependent inhibition of Fe-NTA induced renal ornithine decarboxylase (ODC) activity. In oxidative stress studies, Fe-NTA alone treatment enhanced lipid peroxidation, accompanied by a decrease in the level of GSH, activities of antioxidants and phase II metabolizing enzymes in kidney concomitant with histolopathological changes. These changes were significantly and dose-dependently alleviated by probucol fed diet. From this data, it can be concluded that probucol can modulates toxic and tumor promoting effects of Fe-NTA and can serve as a potent chemopreventive agent to suppress oxidant induced tissue injury and carcinogenesis, in addition to being a cholesterol lowering and anti-atherogenic drug.
The free radical theory of aging (FRTA) suggests that free radicals are the leading cause of deteriorating physiologic function during senescence. Free radicals attack cellular structures or molecules such as DNA resulting in various modifications to the DNA structures. Accumulation of unrepaired DNA contributes to a variety of disorders associated with the aging process.
A standardized mixture of Chinese herbs, Zemaphyte taken orally as a daily decoction has been shown to be effective in the treatment of atopic eczema. This study showed that Zemaphyte is an efficient antioxidant, being capable of scavenging both superoxide and hydroxyl, and preventing peroxidation of biological membranes. It does not degrade hydrogen peroxide directly, but instead most likely forms a Zemaphyte-hydrogen peroxide complex. The complexed hydrogen peroxide can then be degraded in the presence of catalase to form oxygen and water. It is conceivable that Zemaphyte may contribute to the down-regulation of the activities of cells implicated in atopic eczema through its antioxidant activities.
Cashew (Anacardium occindentale L) leaves extract (CLE) has potential as tyrosinase inhibitor that can be used for therapeutic in pigmentation problem. This study investigates the real potential of CLE to inhibit tyrosinase and melanin reduction using human epidermal melanocytes. The extracts were exposed to the human melanocytes for more than 24 hours. The CLE extract exhibited potential as tyrosinase inhibitor, reduced melanin and high in antioxidant activity relative to commercial extract of Emblica sp.
Lead (Pb) is a neurotoxic heavy metal and children in the developmental stage are particularly susceptible to toxic effects of lead exposure. The brain is the key organ involved in interpreting and responding to potential stressors. Epidemiological investigations have established the relationship between chronic lead exposure and cognitive impairments in young children. Excessive production of radical species plays an important role in neuronal pathology resulting from excitotoxic insults, therefore one plausible neuroprotective mechanism of bioflavonoids is partly relevant to their metal chelating and antioxidant properties. Centella asiatica (CA) is a tropical medicinal plant enriched with bioflavonoids and triterpenes and selenium, reported to rejuvenate the cells and promote physical and mental health. Bioflavonoids are claimed to be exert antimutagenic, neurotrophic and xenobiotics ameliorating and membrane molecular stabilizing effects. The objective of the present work is to study the protective antioxidant effect of pretreatment of CA extract (CAE) on lead acetate induced changes in oxidative biomarkers in the central nervous system (CNS) of mice.
The aim of this study was to investigate the effects of vitamin E on the levels of lipid peroxidation and antioxidant enzymes in rat bones. Fifty-six normal male Sprague-Dawley rats, aged 3 months, were randomly divided into seven groups with eight rats in each group. The age-matched control group was given the vehicle olive oil, by oral gavage daily. Six of the treatment groups received either palm tocotrienol or pure alpha-tocopherol at the dose of 30, 60 or 100 mg/kg body weight, by oral gavage daily, 6 days a week for 4 months. Thiobarbituric acid-reactive substance (TBARS) that is an index to measure the level of lipid peroxidation and the antioxidant enzymes, glutathione peroxidase and superoxide dismutase levels were measured in the femur at the end of the study. Palm tocotrienol at the dose of 100 mg/kg body weight significantly reduced the TBARS level in the femur with a significant increase in glutathione peroxidase activity compared to the age-matched control group. These were not observed in the alpha-tocopherol groups. Palm tocotrienol was more effective than pure alpha-tocopherol acetate in suppressing lipid peroxidation in bone. Palm tocotrienol showed better protective effect against free radical damage in the femur compared to alpha-tocopherol. This study suggests that palm tocotrienol plays an important role in preventing imbalance in bone metabolism due to free radicals.
The effects of Carica papaya leaf (CPL) aqueous extract on alcohol induced acute gastric damage and the immediate blood oxidative stress level were studied in rats. The results showed that gastric ulcer index was significantly reduced in rats pretreated with CPL extract as compared with alcohol treated controls. The in vitro studies using 2,2-Diphenyl-1-Picryl-Hydrazyl (DPPH) assay showed strong antioxidant nature of CPL extract. Biochemical analysis indicated that the acute alcohol induced damage is reflected in the alterations of blood oxidative indices and CPL extract offered some protection with reduction in plasma lipid peroxidation level and increased erythrocyte glutathione peroxidase activity. Carica papaya leaf may potentially serve as a good therapeutic agent for protection against gastric ulcer and oxidative stress.
Cocoa and cocoa products have received much attention due to their significant polyphenol contents. Cocoa and cocoa products, namely cocoa liquor, cocoa powder and chocolates (milk and dark chocolates) may present varied polyphenol contents and possess different levels of antioxidant potentials. For the past ten years, at least 28 human studies have been conducted utilizing one of these cocoa products. However, questions arise on which of these products would deliver the best polyphenol contents and antioxidant effects. Moreover, the presence of methylxanthines, peptides, and minerals could synergistically enhance or reduce antioxidant properties of cocoa and cocoa products. To a greater extent, cocoa beans from different countries of origins and the methods of preparation (primary and secondary) could also partially influence the antioxidant polyphenols of cocoa products. Hence, comprehensive studies on the aforementioned factors could provide the understanding of health-promoting activities of cocoa or cocoa products components.
Natural compounds with possible health benefits have become attractive targets for research in areas pertaining to human health. For both prevention and therapy of various human ailments, such compounds are preferred over synthetic ones due to their lesser toxicity. They are also easily absorbed and processed by our body. Vitamins are prominent among natural or endogenous compounds that are considered to be beneficial. The vitamin E group of compounds is among the better known of the vitamins due to their suggested health benefits including antioxidant and related protective properties. Among these, tocotrienols have gained prominence in recent years due to their potential applications and better protective effects in certain systems. These tocotrienols are vitamin E derivatives that are analogs of the more established forms of vitamin E namely tocopherols. In addition to their potent antioxidant activity, tocotrienols have other important functions, especially in maintaining a healthy cardiovascular system and a possible role in protection against cancer and other ailments.
This study investigates the effects of tocotrienol (TT) or alpha-tocopherol (TF) supplementation on corticosterone level, noradrenalin level and gastric lesions in rats exposed to restraint stress. Twenty-four male Sprague Dawley rats were randomly assigned into 4 equally sized groups; two control groups were given olive oil, while the treated group was supplemented with either tocotrienol of tocopherol orally at a dose of 60 mg/kg body weight. After 28 days of treatment, one control group, TT group and TF group were subjected to restraint stress, 2 hours daily for 4 consecutive days. After the last exposure to stress, plasma samples were taken to determine the corticosterone and noradrenalin levels, after which the rats were sacrificed. The stomach was excised for the evaluation of gastric lesions. Our findings showed that TT and TF were able to maintain the corticosterone level to the prestress values, while only TT was able to maintain the noradrenalin level in rats exposed to stress. Tocotrienol was found to be better in preventing formation of gastric lesions compared to TF. As a conclusion, the protective effect of vitamin E was related to the ability to inhibit stress induced elevation of corticosterone and noradrenalin levels.
There is accumulating data demonstrated hypercholesterolemia and oxidative stress play an important role in the development of atherosclerosis. In the present study, a protective activity of alpha-lipoic acid; a metabolic antioxidant in hypercholesterolemic-induced animals was investigated. Eighteen adult male New Zealand White (NZW) rabbit were segregated into three groups labelled as group K, AT and ALA (n=6). While group K was fed with normal chow and acted as a control, the rest fed with 100 g/head/day with 1% high cholesterol diet to induce hypercholesterolemia. 4.2 mg/body weight of alpha lipoic acid was supplemented daily to the ALA group. Drinking water was given ad-libitum. The study was designed for 10 weeks. Blood sampling was taken from the ear lobe vein at the beginning of the study, week 5 and week 10 and plasma was prepared for lipid profile estimation and microsomal lipid peroxidation index indicated with malondialdehyde (MDA) formation. Animals were sacrificed at the end of the study and the aortas were excised for intimal lesion analysis. The results showed a significant reduction of lipid peroxidation index indicated with low MDA level (p<0.05) in ALA group compared to that of the AT group. The blood total cholesterol (TCHOL) and low density lipoprotein (LDL) levels were found to be significantly low in ALA group compared to that of the AT group (p<0.05). Histomorphometric intimal lesion analysis of the aorta showing less of atheromatous plaque formation in alpha lipoic acid supplemented group (p<0.05) compared to that of AT group. These findings suggested that apart from its antioxidant activity, alpha lipoic acid may also posses a lipid lowering effect indicated with low plasma TCHOL and LDL levels and reduced the athero-lesion formation in rabbits fed a high cholesterol diet.
Auricularia auricula-judae is currently grown in Malaysia. In the present study, the methanolic extracts from fruit bodies (fresh, oven-dried, and freeze-dried) and mycelium of A. auricula-judae were evaluated for their antioxidant capacities based on 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. The total phenolic content in the extracts were also measured. The extract of freeze-dried fruit bodies of A. auricula-judae had potent DPPH free radical scavenging activity with a 50% effective concentration of 2.87 mg/mL, whereas the FRAP value of A. auricula-judae mycelium was 5.22 micromol of FeSO(4).7H(2)O equivalents/g of mycelium sample. Further, a positive correlation (R(2) = 0.7668) between FRAP level of A. auricula-judae extracts and the total phenolic contents was observed. Thus the method of processing of fresh fruit bodies had an effect on the antioxidant potential of A. auricula-judae.
Curcumin (diferuloylmethane), a biologically active ingredient derived from rhizome of the plant Curcuma longa, has potent anticancer properties as demonstrated in a plethora of human cancer cell lines/animal carcinogenesis model and also acts as a biological response modifier in various disorders. We have reported previously that dietary supplementation of curcumin suppresses renal ornithine decarboxylase (Okazaki et al. Biochim Biophys Acta 1740:357-366, 2005) and enhances activities of antioxidant and phase II metabolizing enzymes in mice (Iqbal et al. Pharmacol Toxicol 92:33-38, 2003) and also inhibits Fe-NTA-induced oxidative injury of lipids and DNA in vitro (Iqbal et al. Teratog Carcinog Mutagen 1:151-160, 2003). This study was designed to examine whether curcumin possess the potential to suppress the oxidative damage caused by kidney-specific carcinogen, Fe-NTA, in animals. In accord with previous report, at 1 h after Fe-NTA treatment (9.0 mg Fe/kg body weight intraperitoneally), a substantial increased formation of 4-hydroxy-2-nonenal (HNE)-modified protein adducts in renal proximal tubules of animals was observed. Likewise, the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and protein reactive carbonyl, an indicator of protein oxidation, were also increased at 1 h after Fe-NTA treatment in the kidneys of animals. The prophylactic feeding of animals with 1.0% curcumin in diet for 4 weeks completely abolished the formation of (i) HNE-modified protein adducts, (ii) 8-OHdG, and (iii) protein reactive carbonyl in the kidneys of Fe-NTA-treated animals. Taken together, our results suggest that curcumin may afford substantial protection against oxidative damage caused by Fe-NTA, and these protective effects may be mediated via its antioxidant properties. These properties of curcumin strongly suggest that it could be used as a cancer chemopreventive agent.
Besides acting as potent free radical scavengers, tocopherols and tocotrienols have been known to have non-antioxidant properties such as the involvement of alpha-tocopherol (alphaT) in PKC pathway and the anti-cancer properties of gamma-tocotrienol (gammaT3). This study aims to elucidate whether protective effects shown by alphaT and gammaT3 in H(2)O(2)-induced neuron cultures have anti-apoptotic or pro-apoptotic tendency toward the initiation of neuronal apoptosis. H(2)O(2) is used to induce apoptosis in primary cerebellar neuron cultures which is attenuated by pretreatment of alphaT or gammaT3 at concentrations < or =10 microM. Similar to our previous work, gammaT3 was found to be neurotoxic at concentrations > or =100 microM, whereas alphaT showed no neurotoxicity. Cellular uptake of gammaT3 was higher than that of alphaT. Treating cells simultaneously with either gammaT3 or alphaT and with then H(2)O(2) led to higher expression of Bax and Bcl-2 than in neurons exposed to H(2)O(2) alone. Analysis of Bcl-2/Bax ratio as 'survival index' showed that both pretreatment of gammaT3 and alphaT followed by H(2)O(2) increase the 'survival index' of Bcl-2/Bax ratio compared to H(2)O(2)-treated cells, while treatment of gammaT3 alone decrease the ratio compared to unchanged Bcl2/Bax ratio of similar treatment with alphaT alone. Similar treatment of gammaT3 decreased p53 expression and activates p38 MAPK phosphorylation, whereas alphaT did not alter its expression compared to H(2)O(2)-treated cells. Treating neurons with only gammaT3 or alphaT increased the expression of Bax, Bcl-2, p53, and p38 MAPK compared to control with gammaT3 exerting stronger expression for proteins involved than alphaT. In conclusion, low doses of gammaT3 and alphaT confer neuroprotection to H(2)O(2)-treated neurons via their antioxidant mechanism but gammaT3 has stronger pro-apoptosis tendency than alphaT by activating molecules involved in the neuronal apoptotic pathway in the absence of H(2)O(2).