Inhibition of benzo[a]pyrene induced mutagenicity and genotoxicity by black tea polyphenols theaflavins and thearubigins in multiple test systems

Gut Microbiota as a Novel Tool to Dissect the Complex Structures of Black Tea Polymers

Thearubigins, polymers of tea catechins, account for more than 20% of the black tea polyphenols and have been reported to be the active components in black tea. However, the chemical structures and underlying mechanisms regarding how the thearubigins, being poorly bioavailable, generate in vivo health benefits are still largely unknown. Using germ-free and specific pathogen-free husbandry conditions combined with LC/MS-based nontargeted and targeted metabolomic analyses, we investigated the role of intestinal bacteria in thearubigin metabolism. Theaflavins and theasinensins were identified as the major microbial metabolites of thearubigins, suggesting that these molecules are the building units for the complex thearubigins. To further confirm this, thearubigin depolymerization was done using menthofuran in an acidic condition. Menthofuran-conjugated theaflavins, theasinensins, and catechins as well as their free forms were detected as the major degradation products of thearubigins. This indicated that theaflavins and theasinensins could be further polymerized through B-type proanthocyanidin linkages. Furthermore, four microbial degradation products were able to be detected in urine samples, suggesting that they can be absorbed into the circulatory system. Using the combination of microbial degradation, metabolomics, and chemical degradation, our results demonstrate that thearubigins are the complex polymers of theaflavins, theasinensins, and catechins and can be metabolized by gut microbiota to their corresponding bioactive and bioavailable smaller molecular metabolites.

Production Mechanisms of Black Tea Polyphenols

Black tea accounts for 70-80% of world tea production, and the polyphenols therein are produced by enzymatic oxidation of four tea catechins during tea fermentation. However, only limited groups of dimeric oxidation products, such as theaflavins, theasinensins, and theacitrins, have been isolated from black tea and chemically characterized. This is largely because of the complexity and heterogeneity of the oxidation products. To determine structures and production mechanisms of uncharacterized black tea polyphenols, in vitro model fermentation experiments using pure catechins and polyphenol oxidase have been applied, and basic oxidation mechanisms have been established. Contemporary methods, such as LC-MS, are also effective to identify catechin oxidation products in black tea. Despite ongoing efforts, almost 60% of the solids in black tea infusion remain uncharacterized. These compounds include the so-called thearubigins, which are a heterogeneous mixture of uncharacterized catechin oxidation products with oligomeric structures. This review summarizes the current knowledge of the production mechanisms of representative black tea polyphenols and presents recent progress in characterization of thearubigins.

Research progress of black tea thearubigins: a review

As the most abundant component in black tea, thearubigins (TRs) contribute a lot to black tea's characteristic color, mouthfeel, and potential health benefits. But compared to lower molecular weight black tea polyphenols, there are fewer researches that focus on TRs because of their heterogeneity. This review summarized recent research progress on (1) isolation method of TRs; (2) structure analysis and formation mechanism of TRs; (3) biofunctions of TRs, including antioxidation, antimutagenic and anticancer effects, effects on mitochondrial activation, gastrointestinal motility and skeletal health, to show some future research aspects and prospects of TRs.

Herbal Gel Formulation Developed for Anti-Human Immunodeficiency Virus (HIV)-1 Activity Also Inhibits In Vitro HSV-2 Infection

Herpes simplex virus-2 (HSV-2) infection is the most common cause of genital ulcers. The impact of ulcers also demonstrates a strong link to the human immunodeficiency virus (HIV) infection. Complications, drug resistance, and side-effects of anti-viral drugs make the treatment of HSV-2 infection challenging. Herbal medicines have shown potential against HSV-2 and HIV infections. In this context, polyherbal gel formulation comprising 50% ethanolic extracts from Acacia catechu, Lagerstroemia speciosa, Terminalia chebula and Phyllanthus emblica has been developed. The gel formulation significantly exhibited virucidal activity against both HIV-1 and HSV-2 infections with IC₅₀, 55.93 ± 5.30 µg/mL and 27.26 ± 4.87 µg/mL, respectively. It also inhibited HSV-2 attachment and penetration to the Vero cells with an IC₅₀ = 46.55 ± 1.25 µg/mL and 54.94 ± 2.52 µg/mL respectively, which were significantly lower than acyclovir. However, acyclovir is more potent in post-infection assay with an IC₅₀ = 0.065 ± 0.01 µg/mL whereas gel formulation showed an IC₅₀ = 469.05 ± 16.65 µg/mL under similar conditions. Gel formulation showed no inhibitory effect on the viability of lactobacilli, human vaginal keratinocyte cells (Vk2/E6E7), and the integrity of the Caco-2 cells monolayer. Gel formulation did not lead to any significant increase in the secretion of pro-inflammatory cytokines and mutagenic index. The proposed gel formulation may be a promising candidate microbicide for the prevention of sexually transmitted HIV-1 and HSV-2.

A new method to prepare and redefine black tea thearubigins

Thearubigins (TRs) are the major components of black tea, which are formed during the fermentation reactions. Although anti-inflammatory and anti-cancer activities of TRs have been reported, the prepared TRs according to the literature methods still contain many floating peaks. It is puzzling whether the observed activities are from TRs or these floating peaks. Thus, it is urgent to develop a method to prepare pure TRs and redefine them. In the present study, we developed a new method, the combination of caffeine precipitation and Sephadex LH-20 column chromatography, to prepare pure TRs. The floating peaks on the hump of the crude TRs were removed, and pure TRs were prepared. The chemical profile of the floating peaks was established using LC/MS, and the major compounds in this fraction were identified as apigenin glycosides, quercetin glycosides, kaempferol glycosides, theaflavins, theasinensin, and galloylglucoses based on the analysis of their tandem mass spectra and in comparison with literature data. This study will pave the way to further study the chemistry and biological activities of TRs and the health effects of black tea consumption.

Antimutagenic and anticlastogenic effects of Turkish Black Tea on TA98 and TA100 strains of Salmonella typhimurium (in vitro) and mice (in vivo)

CONTEXT

Black tea has been reported to have significant antimutagenic and anticarcinogenic properties associated with its polyphenols theaflavins (TF) and thearubigins (TR). Similarly, Turkish black tea (TBT) also contains a considerable amount of TF and TR.

OBJECTIVE

This study investigated the mutagenic, antimutagenic and anticlastogenic properties of TBT.

MATERIALS AND METHODS

The mutagenic and antimutagenic effects of TBT (10 to 40000 μg/plate) were investigated in vitro on Salmonella strains TA98 and TA100 with and without S9 fraction. Anticlastogenic effect was studied at concentrations of 300-1200 mg/kg TBT extract by chromosomal aberrations (CA) assay from bone marrow of mice.

RESULTS

The results of this study did not reveal any mutagenic properties of TBT. On the contrary, TBT extract exhibited antimutagenic activity at >1000 μg/plate concentrations in TA98 strain with and without S9 activation (40% inhibition with S9 and 27% without S9). In TA100 strain, the antimutagenic activity was observed at >20,000 μg/plate TBT extracts without S9 activation (28% inhibition) and at >1000 μg/plate with S9 activation (59% inhibition). A significant decrease in the percentage of aberrant cells (12.33% ± 1.27) was observed in dimethylbenz(a)anthracene (DMBA) plus highest concentration (1200 mg/kg) of TBT extract-treated group when compared to only DMBA-treated group (17.00% ± 2.28).

DISCUSSION AND CONCLUSION

Results indicated that TBT can be considered as genotoxically safe, because it did not exert any mutagenic and clastogenic effects. As a result, TBT exhibited antimutagenic effects more apparently after metabolic activation in bacterial test system and had an anticlastogenic effect in mice.

Research progress on theaflavins: efficacy, formation, and preparation

Background: Theaflavins (TFs) are a category of natural compounds characterized with the benzotropolone skeleton. The prominent benefits of TFs have been well documented. Amount of research were conducted and excellent achievements were disclosed during the past years. However, as far as we know, there is no comprehensive review about TFs. Scope and approach: This review summarized the recent research progress. The activity of TFs on anti-oxidation, anti-mutagenicity, hypolipidemic, anti-inflammatory, anti-cancer, anti-viral effect as well as the epidemiological cure were sorted. Converging pioneer literature and deduction, the underlying formation mechanism of TFs was proposed. Subsequently, acquisition of TFs was pointed out to be the fundament for further research. Accelerated by enzyme, bio-synthesis of TFs were reviewed simultaneously. At the end, employing modern analysis instrument and technology, isolations of TFs were enumerated. Key findings and conclusions: Structure of the skeleton as well as functional groups were paramount related with the bio-activity of TFs. Meanwhile, oxidation pathway of two catechin molecules to form TFs were hypothesized. Also, ascertainment of the several therapeutic efficiency of the family members of TFs would be the next step in the future.

Effects of Kaolin (M-99-099) Application on Antioxidant and Phenolic Compounds in Tea Leaves (Camellia sinensis L.O. Kuntze)

In this study, the effects of kaolin (M-99-099) applications on the total phenolic and antioxidant contents of tea leaves (Camellia sinensis (L.) O. Kuntze) harvested in three different periods were investigated. For this purpose, four different strategies including standard fertilizer application (T), 3% kaolin+standard fertilizer application (Ka₁), 6% kaolin+standard fertilizer application (Ka₂), and control (C) (nothing applied) were used to compare the effects of these strategies on total phenolic content, FRAP values, and DPPH radical scavenging capacities of tea leaves. It has been proven that the kaolin applications, Ka₁ and Ka₂, increase the phenolic content and antioxidant contents of tea samples. While the kaolin applications have higher values at 1st harvest than those of T and C, they have the lowest values at 3rd harvest.

Safety evaluation of styrax liquidus from the viewpoint of genotoxicity and mutagenicity

ETHNOPHARMACOLOGICAL RELEVANCE

Styrax liquidus is a resinous exudate (balsam) obtained from the wounded trunk of the Liquidambar orientalis Mill. (Hamamelidaceae). Styrax has been used for treatment of various ailments in Turkish folk medicine such as skin problems, peptic ulcers, nocturnal enuresis, parasitic infections, antiseptic or as expectorant.

AIM OF STUDY

In spite of frequent use of styrax in Turkish folk medicine as well as once as a stabilizer in perfumery industry, negative reports have been noticed by the international authority for restriction its use based on some limited evidences from an in vitro study. The aim of the present study was to evaluate the genotoxic and cytotoxic potential of styrax and its ethanolic extract using in vivo and in vitro assays, as well as an antimutagenic assay and also to determine its phenolic constituents with chromatographic analysis.

MATERIALS AND METHODS

In vitro mutagenicity and antimutagenicity of styrax and its ethanolic extract were evaluated by Ames test performed on Salmonella TA98 and TA100 strains with and without metabolic activation (10- 30,000µg/plate). The genotoxicity was also studied in vivo by chromosomal aberrations assay on bone marrow of Balb C mice with different its concentrations (500-2000mg/kg body weight). Cytotoxicity has been evaluated by the MTT assay using L929 cell line. Its phenolic constituents were determined by HPLC analysis.

RESULTS

Genotoxicological investigations of styrax or its ethanolic extract showed that none of the tested concentrations induced a significant increase in the revertant number of TA98 and TA100 strains with or without metabolic activation, indicating no mutagenicity to the tested strains. Also results indicated that up to 2000mg/kg body weight, styrax is not genotoxic in mammalian bone marrow chromosome aberration test in vivo. In cytotoxicity study, the IC₅₀ values of styrax and its ethanolic extract were found to be 50.22±1.80 and 59.69±11.77µg/mL, respectively. Among the studied reference standards the major phenolic acids in styrax balsam was found to be p-coumaric acid (2.95mg/g), while in its ethanolic extract not only p-coumaric acid (11.46mg/g), but also gallic acid (1.60mg/g) were found to the main components.

CONCLUSION

The findings of the present study provide scientific basis to the safety of styrax from the viewpoint of genotoxicity risk, and in fact, it was found to be beneficial against genotoxicity.

Evaluation of the mutagenic and genotoxic effects of the ALC67 thiazolidine compound in Salmonella strains and human lymphocytes in vitro

ALC67 is an N-acylated thiazolidine compound with promising anticancer activity that led to the recent discovery of a series of 3-propionyl thiazolidine-4-carboxylic acid ethyl esters as a family of novel antiproliferative agents. Since the mutagenic and genotoxic properties of marketed anticancer molecules constitute a main issue to be addressed, this study focused on the analysis of the mutagenicity, antimutagenecity, and genotoxicity of this molecule. The mutagenicity and antimutagenicity of ALC67 were evaluated by Ames test performed on Salmonella TA98 and TA100 strains. The genotoxicity of this molecule was investigated in the chromosomal aberration assay on human lymphocytes. All results revealed that the analyzed structure is not mutagenic in the two Salmonella strains tested and was not genotoxic in human lymphocytes in vitro On the other hand, it showed a weak antimutagenic effect in these two bacterial strains. The above results indicate that after performing some more mutagenicity assays using the other recommended strains, this compound can be safely used for the development of new structures exhibiting anticancer activities.

Acaciaside-B-enriched fraction of Acacia auriculiformis is a prospective spermicide with no mutagenic property

As a part of our continued venture to develop a safe and effective spermicide, we have identified a triterpene glycoside (Acaciaside-B (Ac-B))-enriched fraction (Ac-B-en) isolated from the seeds of Acacia auriculiformis and evaluated its spermicidal potential in vitro. Sperm motility was completely inhibited within 20 s at a minimum effective concentration (MEC) of 120 microg/ml. Tests for sperm viability by dual fluoroprobe staining showed the effect to be spermicidal with an EC(50) of 35.20 microg/ml. A series of investigations including tests for hypo-osmotic swelling, membrane lipid peroxidation, and electron microscopy document that the spermicidal effect of the fraction involves loss of sperm plasma membrane integrity and dissolution of the acrosomal vesicle--the two most important structural components that play diverse roles in physiological functions of sperm including fertilization. The fraction at 10 x MEC exerted no detrimental effects on in vitro growth of Lactobacillus acidophilus, which is considered the major constituent of vaginal microflora that maintains vaginal health. Ames tests performed with different strains of Salmonella typhimurium including TA 97a, 98, 100, and 102, which detect mutagens causing bp substitution or frameshifting at G-C or A-T bp, demonstrate no mutagenic potential of the fraction. Significant spermicidal potential with no possible mutagenic effect and adverse impacts on lactobacilli growth attests to the credential of Ac-B-en as a prospective future spermicide for the development of a safe and effective vaginal contraceptive formulation.

Comparative antimutagenic and anticancer activity of three fractions of black tea polyphenols thearubigins

Antimutagenic and anticancer effects of black tea polyphenols theaflavins (TF) and thearubigins (TR) have previously been reported. TR is a complex mixture of polyphenols. In this study, our interest was to fractionate TR and to study the antimutagenic and anticancer activities of the fractions. Three fractions of TR, namely TR-1, TR-2, and TR-3, were isolated by chromatographic processes. Antimutagenic activity of these 3 fractions was carried out on 4 Salmonella strains by Ames assay. Anticancer activity was studied on human leukemic cells U937. Our findings clearly indicated antimutagenic and anticancer activities of the TR-1, TR-2, and TR-3 fractions on Salmonella strains and on U937 cells, respectively. However, all 3 fractions, at or below 100 μg/ml dose, did not show any significant toxic effects on the normal human cells (peripheral blood mononuclear cells). TR-2 was found to be the most active fraction among the 3. Flow cytometric and confocal microscopic studies further indicate that apoptosis induction could be an important mechanism behind the anticancer effects of these fractions. To our knowledge, this study is the first attempt to describe the antimutagenic and anticancer activity of TR fractions, and it also suggests that TR-2 is the most active component of TR.

Nigella sativa: reduces the risk of various maladies

Coinage of terms like nutraceuticals, functional, and pharma foods has diverted the attention of human beings to where they are seeking more natural cures. Though pharmaceutical drugs have been beneficial for human health and have cured various diseases but they also impart some side effects. Numerous plants have been tested for their therapeutic potential; Nigella sativa, commonly known as black cumin, is one of them. It possesses a nutritional dense profile as its fixed oil (lipid fraction), is rich in unsaturated fatty acids while essential oil contains thymoquinone and carvacrol as antioxidants. N. sativa seeds also contain proteins, alkaloids (nigellicines and nigelledine), and saponins (alpha-hederin) in substantial amounts. Recent pharmacological investigations suggested its potential role, especially for the amelioration of oxidative stress through free radical scavenging activity, the induction of apoptosis to cure various cancer lines, the reduction of blood glucose, and the prevention of complications from diabetes. It regulates hematological and serological aspects and can be effective in dyslipidemia and respiratory disorders. Moreover, its immunopotentiating and immunomodulating role brings balance in the immune system. Evidence is available supporting the utilization of Nigella sativa and its bioactive components in a daily diet for health improvement. This review is intended to focus on the composition of Nigella sativa and to elaborate its possible therapeutic roles as a functional food to prevent an array of maladies.

Role of oxidation-triggered activation of JNK and p38 MAPK in black tea polyphenols induced apoptotic death of A375 cells

Theaflavins (TF) and thearubigins (TR) are the major polyphenols of black tea. Our previous study revealed that TF- and TR-induced apoptosis of human malignant melanoma cells (A375) is executed via a mitochondria-mediated pathway. In our present study we observed the role of the three most important MAPK (ERK, JNK, and p38) in TF- and TR-induced apoptosis. TF and TR treatment of A375 cells led to sustained activation of JNK and p38 MAPK but not ERK, suggesting that JNK and p38 are the effector molecules in this polyphenol-induced cell death. This idea was further supported by subsequent studies in which JNK and p38 activation was inhibited by specific inhibitors. Significant inhibition was found in TF- and TR-treated A375 cell death pretreated with JNK- or p38-specific inhibitors only. Further, we have found that TF and TR treatment induces a time-dependent increase in intracellular reactive oxygen species generation in A375 cells. Interestingly, treatment with the antioxidant N-acetyl cystein inhibits TF- and TR-induced JNK and p38 activation as well as induction of cell death in A375 cells. We also provide evidence demonstrating the critical role of apoptosis signal-regulating kinase 1 in TF- and TR-induced apoptosis in A375 cells. Taken together our results strongly suggest that TF and TR induce apoptotic death of A375 cells through apoptosis signal-regulating kinase 1, MAPK kinase, and the JNK-p38 cascade, which is triggered by N-acetyl cystein intracellular oxidative stress.

A thought on the biological activities of black tea

Tea is the most widely used ancient beverage in the world and black tea possesses many biological effects on the organisms. It acts as an effective antioxidant because of its free radical-scavenging and metal-chelating ability. Due to this, it is active against inflammation, clastogenesis, and several types of cancer. Tea reduces DNA damage and mutagenesis due to oxidative stress or the presence of pro-mutagens through antioxidant function, blocking activation pathways of mutagens, suppressing transcription of enzymes involved etc. Inhibition of low-density lipoprotein (LDL) peroxidation, suppression of fatty acid synthase etc., suggest that tea may have a role in preventing cardiovascular diseases. Some epidemiological studies support the protective role of black tea against cardiovascular diseases but some do not. Besides, black tea has beneficial effects on the gastrointestinal tract; it affects motility, absorption, microflora etc., by influencing the hormonal balance and antioxidant function black tea improves bone mineral density. It is also antiviral due to its enzyme-inhibiting and receptor-blocking properties. Although its role in cancers of the gastrointestinal tract, liver, and prostate is confirmed, its effect against urinary tract cancer is uncertain and further studies are required. Apart from these, excess consumption may lead to the formation of a stained pellicle layer on teeth, which is difficult to eliminate, inhibits trypsin, influences mineral absorption, causes convulsions etc. Excess caffeine intake may have adverse effects on selected organs as reported in studies on some organisms. These reports indicate that there is a wide scope of further research for the efficient use of black tea active conserves/isolates to reap health benefits.

Cytogenetic effects of grape extracts (Vitis vinifera) and polyphenols on mitomycin C-induced sister chromatid exchanges (SCEs) in human blood lymphocytes

In the present study, the effects of extracts and polyphenol-rich fractions as well as monomer polyphenols identified in them, from both red and white grapes, on mitomycin C (MMC) induced sister chromatid exchanges (SCEs) in human peripheral blood lymphocytes were investigated. The grape extracts and two of the three polyphenol-rich fractions promoted MMC-induced SCEs at concentrations from 75 to 300 microg/mL. However, none of the extracts or fractions alone induced SCEs. Thus, these results suggest caution especially with regard to the use of grape extracts as dietary supplements. On the other hand, the fact that these extracts were not genotoxic alone may indicate a selective activity against genetically damaged cells. This is the first study regarding the clastogenic effects of grape extracts in human cells. Moreover, from the tested polyphenols, caffeic acid, gallic acid, and rutin hydrate enhanced MMC-induced clastogenicity, whereas ferulic acid, protocatechuic acid, (+)-catechin, (-)-epicatechin, and trans-resveratrol had no effect at concentrations between 5 and 100 microM. The differences in the chemical structures of the tested polyphenols may account for their differential effects on MMC clastogenicity.

Effect of extraction conditions on measured total polyphenol contents and antioxidant and antibacterial activities of black tea

Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was found to be in the range of 0.44-114.01 mg gallic acid equivalents (GAE)/g dry weight tea, depending on the solvent used and the length of the extraction process. In general, aqueous acetone or DMF extracts displayed the highest polyphenol contents and antioxidant activity, while absolute acetone was the least efficient solvent. Antioxidant activities of tea extracts tested using the reducing power and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods ranged from 0.09 to 1.18 and from 2.60 to 95.42 %, respectively, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. Aqueous solvent black tea extracts also possessed antibacterial activity, depending on the solvent used and bacterial species tested. Staphylococcus aureus was found to be the most sensitive to all tea extracts, except for the methanol extract. Tea extracts were not effective against Y. enterocolitica, L. monocytogenes and E. coli O157:H7.

Anticlastogenic activity of thymoquinone against benzo(a)pyrene in mice

Thymoquione (TQ), the main constituent of the volatile oil of Nigella sativa seeds, has been shown to protect mice against benzo(a)pyrene [B(a)P]-induced forestomach carcinogenesis. The present investigation was undertaken to study the possible chemopreventive activity of TQ, supplemented in the drinking water, against B(a)P-induced chromosomal aberrations (CAs) in mouse bone marrow cells. Male Swiss albino mice received TQ (0.01% in drinking water) daily for 28 days. The daily dose of TQ was estimated to be 10mg/kg based on the calculated average daily water consumption by mice. From day 9, the carcinogen, B(a)P, was given by gastric intubation at dose level of 50mg/kg on alternative days for a total of 8 doses. On day 29, all mice were transferred to a normal drinking tap water. Control groups received corn oil vehicle, TQ alone or B(a)P alone. All mice were sacrificed at 12 weeks after the end of the treatment. Chromosome preparations were made of bone marrow. Cytogenetic end points screened were the frequencies of CAs and damaged cells induced. Daily intake of TQ after and before or during exposure to B(a)P significantly reduced the frequencies of CAs and damaged cells compared to the highly clastogenic activity of B(a)P alone.

Anticlastogenic effects of black tea polyphenols theaflavins and thearubigins in human lymphocytes in vitro

Black tea accounts for nearly 80% of total World tea production. It contains dimeric flavanols and polymeric polyphenols known as theaflavins (TF) and thearubigins (TR). TR is exclusively present in black tea. On the basis of our previous potent antimutagenic and anticlastogenic effects of TF and TR in vitro in bacterial system and in vivo in mouse bone marrow cells, we have decided to extend our study in human cells in vitro. This study investigated the anticlastogenic effects of black tea polyphenols TF and TR as measured by chromosomal aberrations (CA) and micronuclei formation (MN) against two known mutagens/carcinogens i.e. benzo[a]pyerne (B[a]P) and aflatoxin B1(AFB1) with S9 activation. A significant decrease in both CA and MN were observed in the human lymphocyte cultures treated with either TF or TR pretreated with either B[a]P or AFB1 (250, 500, 1000 microg/ml) when compared with B[a]P or AFB1 treated cultures alone. TF shows more protective effects than TR in this in vitro system. These results indicate that both TF and TR have significant anticlastogenic effects in vitro in human lymphocytes.

Neuroprotective and neurorescue effect of black tea extract in 6-hydroxydopamine-lesioned rat model of Parkinson's disease

In the present study, an attempt has been made to explore the neuroprotective and neuroreparative (neurorescue) effect of black tea extract (BTE) in 6-hydroxydopamine (6-OHDA)-lesioned rat model of Parkinson's disease (PD). In the neuroprotective (BTE + 6-OHDA) and neurorescue (6-OHDA + BTE) experiments, the rats were given 1.5% BTE orally prior to and after intrastriatal 6-OHDA lesion respectively. A significant recovery in d-amphetamine induced circling behavior (stereotypy), spontaneous locomotor activity, dopamine (DA)-D2 receptor binding, striatal DA and 3-4 dihydroxy phenyl acetic acid (DOPAC) level, nigral glutathione level, lipid peroxidation, striatal superoxide dismutase and catalase activity, antiapoptotic and proapoptotic protein level was evident in BTE + 6-OHDA and 6-OHDA + BTE groups, as compared to lesioned animals. BTE treatment, either before or after 6-OHDA administration protected the dopaminergic neurons, as evident by significantly higher number of surviving tyrosine hydroxylase immunoreactive (TH-ir) neurons, increased TH protein level and TH mRNA expression in substantia nigra. However, the degree of improvement in motor and neurochemical deficits was more prominent in rats receiving BTE before 6-OHDA. Results suggest that BTE exerts both neuroprotective and neurorescue effects against 6-OHDA-induced degeneration of the nigrostriatal dopaminergic system, suggesting that possibly daily intake of BTE may slow down the PD progression as well as delay the onset of neurodegenerative processes in PD.