Cytotoxic and apoptogenic effect of Swietenia mahagoni (L.) Jacq. leaf extract in human leukemic cell lines U937, K562 and HL-60.

The apoptogenic activity of Swietenia mahagoni leaf extract (SMLE) was investigated against three human leukemic cell lines - U937, K562 and HL-60. SMLE inhibited cell growth and metabolic activity of the leukemic cells and showed characteristic features of apoptosis. Flow-cytometric analysis showed that SMLE arrested U937 and K562 cell populations in the G2-M phase and the HL-60 cell population in the G1 phase of cell cycle. SMLE induced apoptosis was found to be mediated through mitochondrial intrinsic pathway involving the release of cytochrome c into the cytosol and activation of caspase-9 and caspase-3. Two flavonoids, catechin and quercetin-3-O-glucoside, isolated from SMLE, were found to inhibit the growth and metabolic activity of U937, K562 and HL-60 cells at much lower concentrations thus indicating that these two flavonoids might be the active ingredients responsible for the anti-leukemic activity of SMLE.

Bio-assay guided isolation of α-glucosidase inhibitory constituents from Hibiscus mutabilis leaves.

INTRODUCTION: The increasing demand for natural-product-based medicines and health-care products for the management of diabetes encouraged investigation of this commonly available Indian plant. OBJECTIVES: To establish the anti-diabetic (α-glucosidase inhibitory) activity of H. mutabilis leaf extract, isolate and identify the constituents responsible for the activity, and validate a HPLC method for quantification of the active constituents for standardisation of the extract. MATERIAL AND METHODS: The methanolic extract of leaves was partitioned between water, n-butanol and ethyl acetate. Bio-assay guided fractionation, based on inhibition of α-glucosidase, allowed isolation and identification of the active components. The active components were quantified using RP-HPLC-DAD validated for linearity, limit of detection, limit of quantification, precision, accuracy and robustness for this plant extract and the partitioned fractions. RESULTS: Ferulic acid and caffeic acid were identified as the α-glucosidase inhibitors present in H. mutabilis. They were partitioned into an ethyl acetate fraction. The HPLC-DAD calibration curve showed good linearity (r² > 0.99). For the recovery studies the %RSD was less than 2%. The interday and intraday variations were found to be less than 4% RSD for retention time and response. CONCLUSION: The identification of α-glucosidase inhibition activity in H. mutabilis supports further investigations into the possible use of the plant for the management of diabetes. The HPLC method validated for these extracts will be useful in future research with the plant.

An insight on the neuropharmacological activity of Telescopium telescopium--a mollusc from the Sunderban mangrove.

The present study was carried out to evaluate the biological properties of the tissue extract of a marine snail Telescopium telescopium, collected from the coastal regions of West Bengal India. On extensive pharmacological screening, it was found that the biological extract of T. telescopium (TTE) produced significant central nervous system (CNS)-depressant activity as observed from the reduced spontaneous motility, potentiation of pentobarbitone induced sleeping time, hypothermia and respiratory depression with transient apnoea. The extract significantly decreased both residual curiosity and also muscle coordination. The fraction, obtained following saturation with 60-80% ammonium sulphate (80S), was also found to demonstrate predominant CNS-depressant activity. It was observed that both TTE and the 80S fraction significantly altered the brain noradrenaline and homovanillic acid levels without affecting the brain gamma amino butyric acid (GABA) concentration. Based on the present observations, it can be suggested that the CNS-depressant effects produced by TTE and 80S could be attributable to modified catecholamine metabolism in the brain.

The theaflavin fraction is responsible for the facilitatory effect of black tea at the skeletal myoneural junction.

The effect of various fractions of black tea [(Camellia Sinensis) (L) O. Kuntze (Theaceae)] on the function of mammalian skeletomotor apparatus was studied. The theaflavin fraction (Tfs) produced a concentration- dependent facilitation of indirect twitch responses of the rat phrenic nerve diaphragm preparation and the facilitation was dependent on the amount of calcium present in the bathing fluid. Nifedipine reduced the facilitatory effect of Tfs as a function of its concentration. Tfs failed to produce facilitation when the twitch height was reduced to about 50% of the control value in presence of magnesium chloride. Tfs completely antagonized the submaximal paralytic effect of d- tubocurarine and decamethonium bromide. Tfs did not have any effect on direct twitch responses or on acetylcholine (Ach) and potassium chloride (KCl) induced contractures of denervated diaphragm. The results revealed that the site of action of Tfs is on the contractile mechanism of the voluntary muscle and point to a critical role of calcium in the mechanism of action of Tfs. N omega-nitro-L-arginine-methyl ester (L-NAME), a nitric oxide synthase (NOS) inhibitor, antagonized both the facilitatory and inhibitory effects on indirect twitch responses of rat diaphragm induced by L-arginine and Tfs when the phrenic nerve was stimulated at 5 Hz and 50 Hz respectively. The thearubigin (Trs) fraction of black tea and the aqueous part which is completely devoid of Tfs, did not potentiate the twitch responses. The findings suggest that Tfs have a potentiating effect on the contractile mechanism of skeletal muscle and that calcium and nitric oxide may modulate this action of Tfs.

Anti-inflammatory activity of tea (Camellia sinensis) root extract.

Pharmacological studies were carried out with methanol-water (1:1) extract of dried tea (Camellia sinensis) root extract (TRE). TRE was found to possess anti-inflammatory, analgesic and antipyretic activities at 1/10th of its LD50 dose of 100 mg/kg i.p. It was found that TRE inhibited the arachidonic acid-induced paw oedema in rats which indicated that TRE produced the anti-inflammatory activity by inhibiting both the cyclooxygenase and lypooxygenase pathways of arachidonic acid metabolism. TRE also enhanced peritoneal cell count and the number of macrophages in normal mice. It is plausible that the saponins present in TRE may be responsible for these activities of TRE.

Curcumin, the major component of food flavour turmeric, reduces mucosal injury in trinitrobenzene sulphonic acid-induced colitis.

1 Inflammmatory bowel disease (IBD) is characterized by oxidative and nitrosative stress, leucocyte infiltration and upregulation of proinflammatory cytokines. In this study, we have investigated the protective effects of curcumin, an anti-inflammatory and antioxidant food derivative, on 2,4,6- trinitrobenzene sulphonic acid-induced colitis in mice, a model for IBD. 2 Intestinal lesions (judged by macroscopic and histological score) were associated with neutrophil infiltration (measured as increase in myeloperoxidase activity in the mucosa), increased serine protease activity (may be involved in the degradation of colonic tissue) and high levels of malondialdehyde (an indicator of lipid peroxidation). 3 Dose-response studies revealed that pretreatment of mice with curcumin (50 mg kg(-1) daily i.g. for 10 days) significantly ameliorated the appearance of diarrhoea and the disruption of colonic architecture. Higher doses (100 and 300 mg kg(-1)) had comparable effects. 4 In curcumin-pretreated mice, there was a significant reduction in the degree of both neutrophil infiltration (measured as decrease in myeloperoxidase activity) and lipid peroxidation (measured as decrease in malondialdehyde activity) in the inflamed colon as well as decreased serine protease activity. 5 Curcumin also reduced the levels of nitric oxide (NO) and O(2)(-) associated with the favourable expression of Th1 and Th2 cytokines and inducible NO synthase. Consistent with these observations, nuclear factor-kappaB activation in colonic mucosa was suppressed in the curcumin-treated mice. 6 These findings suggest that curcumin or diferuloylmethane, a major component of the food flavour turmeric, exerts beneficial effects in experimental colitis and may, therefore, be useful in the treatment of IBD.

Antidiarrhoeal activity of hot water extract of black tea (Camellia sinensis).

The effect of a hot water extract of black tea (Camellia sinensis (L.) O. Kuntze, Theaceae) on upper gastrointestinal transit and on diarrhoea was investigated employing conventional rodent models of diarrhoea. Black tea extract was found to possess antidiarrhoeal activity in all the models of diarrhoea used. Naloxone (0.5 mg/kg i.p.) significantly inhibited the antidiarrhoeal activity of the extract as well as loperamide, thus indicating a role of the opioid system in the antidiarrhoeal activity of the extract.

Glycosmis arborea extract as a hepatoprotective agent.

Glycosmis arborea is a plant possessing various medicinal properties. The aim of the present study was to investigate the hepatoprotective efficacy of the butanol extract obtained from the aerial parts of the plant. The test sample was prepared by extracting the material through different steps. The extract thus obtained was dissolved in normal saline. Albino rats were prophylactically treated with the extract (i.p.) for 3 weeks. At the end of 3rd week all the groups were injected with hepatotoxic agents. After 48 h of injection, blood was collected and livers were taken out. Different enzymes in the serum were assayed and histopathological study was performed with liver. Glycosmis arborea extract was able to overcome the toxic effects of hepatotoxic agents in terms of lowering the levels of serum GPT, alkaline phosphatase and increased level of SOD in serum. TBARS generation in liver was also altered. Moreover, necrosis of liver produced by carbon tetrachloride was reversed by the extract.

Antineoplastic effect of new boron compounds against leukemic cell lines and cells from leukemic patients.

Three new boron compounds, dihydroxy (oxybiguanido) boron (iii) hydrochloride monohydrate (HB), guanidine biboric acid adduct (GB) and hydroxosalicyl hydroxomato boron (iii) (SHB) were studied to observe their antineoplastic effect, if any. Leukemic cells isolated from acute lymphatic leukaemia (ALL) patients and chronic myeloid leukaemia patients (CML) and myeloid leukemia cell lines (HL 60 and U-937) showed cell growth inhibition after treatment with the boron compounds. MTT assay showed that the growth of metabolically active cells was inhibited by treatment with these drugs. The molecular mechanism by which SHB induced apoptosis in immature blast cells was also investigated by ladder formation in gel electrophoresis.

Antidiarrhoeal activity of seed extract of Albizzia lebbeck Benth.

The antidiarrhoeal activity of the seed extract of Albizzia lebbeck (Benth.) was investigated employing conventional rodent models of diarrhoea, i.e. castor oil-induced diarrhoea, upper gastrointestinal transit (u.g.t.) and fluid secretion. It was found that the aqueous methanol extract of Albizzia lebbeck seeds (2.5-5 mg/kg i.p.) possessed antidiarrhoeal activity which strengthens the earlier use of the seeds in the treatment of diarrhoea and dysentery. The antidiarrhoeal dose of the extract was at least 10-30 times less than the LD(50) dose. The extract (2.5-5 mg/kg i.p.) potentiated the antidiarrhoeal activity of loperamide (1 mg/kg i.p.). Nalaxone (0.5 mg/kg i.p.) significantly inhibited the antidiarrhoeal activity of the extract as well as loperamide, thus indicating a role of the opioid system in the antidiarrhoeal activity of the extract.

Inhibition of tumour growth and inflammation by consumption of tea.

The antitumour effect of tea was evaluated in the 3-methylcholanthrene (3-MC) induced solid tumour model in mice. Both black and green tea inhibited tumour growth and prevented metastasis. Histopathological study showed that tea treatment was able to reduce malignancy. Superoxide dismutase (SOD), a free radical scavenger, was found to be significantly increased in the serum of mice administered tea. Moreover, tea extracts were able to reduce the level of thiobarbituric acid reactive substance (TBARS) in the sera of mice. Tea extracts (both black and green) also showed antiinflammatory activity in the carrageenan-induced paw oedema model in the rat.

Studies with black tea and its constituents on leukemic cells and cell lines.

The anticancer effect of black tea (BT) and its polyphenols theaflavin (TF) and thearubigin (TR) has been evaluated on U-937 cell line, a myeloid leukemic cell line and on leukemic cells isolated from peripheral blood of chronic myeloid leukemia (CML) patients. In both types of cells, cell growth inhibition was observed 24 hrs after treatment with BT, TF and TR. MTT assay showed growth inhibition of metabolically active cells and inhibition of DNA synthesis was observed by 3H-Thymidine incorporation after treatment with the compounds. In all cases TF and TR were more effective than BT, suggesting that these are possibly the active components in BT responsible for its antileukemic activity. Superoxide dismutase (SOD), a free radical scavenger, was found to be increased by TF, whereas BT and TR lowered the level in comparison to the control. The present study is the first report of antileukemic effect of BT and its polyphenols.

Role of reduced glutathione and nitric oxide in the black tea extract-mediated protection against ulcerogen-induced changes in motility and gastric emptying in rats.

The aim of the present study was to investigate the underlying mechanism of the role of hot water extract of black tea [Camellia sinensis (L). O. Kuntze Theaceae] in normalizing the changes in intestinal transit and gastric emptying induced by various ulcerogenic agents in experimental rats. Intestinal transit as well as gastric emptying were significantly reduced in rats treated with glutathione (GSH) depleting agents, diethyl maleate (DEM), indoacetamide (IDA) and N-ethyl maleimide (NEM). Prior oral administration of black tea extract (BTE) at 20 ml/kg of a 10% solution, i.g. once a day for 7 days significantly increased the intestinal transit and gastric emptying with restoration of serum GSH level. Singular administration of succimer (60 mg/kg, i.g.), the standard sulfhydryl containing antiulcer agent used as a reference drug, was also effective. Increase in intestinal transit caused by BTE was reversed both by N-omega-nitro-L-arginine methyl ester (L-NAME) (25 mg/kg, i.p.) and N-omega-monomethyl-L-arginine (L-NMMA) (25 mg/kg, i.p.), but not with N-omega-nitro-D-arginine methyl ester (D-NAME) (25 mg/kg, i.p.). Furthermore, restoration of intestinal nitric oxide synthase (NOS) activity was found to be associated with BTE treatment. These results provide evidence that nitric oxide may play a role in BTE-mediated improvement of intestinal motility changes and gastric emptying induced by DEM, IDA and NEM.

Trigonella foenum graecum (fenugreek) seed extract as an antineoplastic agent.

The antineoplastic effect of Trigonella foenum graecum seed extract has been evaluated in the Ehrlich ascites carcinoma (EAC) model in Balb-C mice. Intra-peritoneal administration of the alcohol extract of the seed both before and after inoculation of EAC cell in mice produced more than 70% inhibition of tumour cell growth with respect to the control. Treatment with the extract was found to enhance both the peritoneal exudate cell and macrophage cell counts. The extract also produced a significant antiinflammatory effect. We report here the antiinflammatory and antineoplastic effects, of Trigonella foenum graecum seed extract.

Antiinflammatory and antioxidant property of saponins of tea [Camellia sinensis (L) O. Kuntze] root extract.

Two groups of saponins, TS-1 and TS-2, isolated from tea root extract (TRE) were tested for antiinflammatory and in vitro antioxidant activity. Both TS-1 and TS-2 inhibited carrageenan-induced paw oedema in rats. The antioxidant activity of these compounds was evaluated using the xanthine-xanthine oxidase system. The study indicated that the previously observed antitumour activity of TRE might be mediated through scavenging of free radicals by saponins and their antiinflammatory activity.

Boron compounds against human leukemic cells.

Two new boron compoumds, dihydroxy(oxybiguanido) boron (iii) hydrochloride monohydrate (HB) and guanidine biboric acid adduct (GB) were used in this study to observe the antitumor effect. Leukemic blast cells isolated from chronic myeloid leukemia (CML) patients showed significant cell growth inhibition within twentyfour hours. IC50 of GB and HB was 2mg/ml. The metabolically active cells were found to be inhibited by drug treatment as assessed by MTT test. Inhibition of 3H Thymidine incorporation also supported the above result. In this study we investigated the molecular mechanisms by which HB and GB induce apoptosis in immature blast cells.

Prokinetic effect of black tea on gastrointestinal motility.

The gastrokinetic effects of hot water extract of black tea [Camellia sinensis, (L) O. Kuntze (Theaceae)] on gastrointestinal motility were studied both in vivo and in vitro. The extract significantly accelerated the gastrointestinal transit (GIT) in vivo in mice. These facilitatory effect was reduced after pretreatment with atropine, hemicholinium-3, morphine, indomethacin, McN-A-343 and L-arginine. In guinea pig ileum, the extract facilitated the peristaltic reflex in response to pressures in normal preparation. The black tea extract and L-NMMA (nitric oxide synthase inhibitor) significantly reduced the electrical field stimulated nonadrenergic, noncholinergic (NANC) relaxation of isolated rat fundal strips. The extract markedly enhanced the tonic ('hump') responses to transmural stimulation in longitudinal muscle of guinea pig ileum which was unaltered in the presence of atropine. These findings suggest a cholinergic involvement and a partial role of prostaglandin and nitric oxide in the mechanism of action of black tea extract on gastrointestinal motility. To determine the effective constituents in black tea responsible for this activity, the effect of black tea polyphenols on GIT were also studied. Thearubigin fraction (but not theaflavin) accelerated GIT significantly which suggests its involvement in the prokinetic effect of black tea.

Proconvulsive effect of tea (Camellia sinensis) in mice.

Investigations were carried out to evaluate the effect of acute and chronic administration of both black and green tea on three models of experimentally induced convulsions in mice. Tea extract (both black and green) significantly accelerated the onset of convulsion, increased the duration of convulsion and mortality in mice. Since both the extracts failed to alter the GABA level in brain, based on the earlier report that both black and green tea might act on Ca(2+) channels, it can be suggested that the observed proconvulsive effect of tea is not mediated through GABA but through Ca(2+) channels.

Role of glutathione in the antiulcer effect of hot water extract of black tea (Camellia sinensis).

The role of a hot water extract of black tea (Camellia sinensis (L). O. Kuntze Theaceae) in the gastric cytoprotective mechanisms was studied using gastric mucosal lesions produced by various ulcerogens in rats as an experimental model. Prior oral administration of black tea extract (BTE) at 20 ml/kg, i.g. once a day for 7 days significantly reduced the incidence of gastric erosions and severity induced by ethanol, diethyldithiocarbamate (DDC) and diethylmaleate (DEM). This treatment also favorably altered the changes in acid and peptic activity of gastric juice in these ulcerogen-treated animals. Singular administration of succimer (60 mg/kg, i.g.), the standard sulfhydryl containing antiulcer drug used as a reference drug, was also effective. The levels of glutathione and glutathione peroxidase were significantly decreased after treatment with ethanol, DDC and DEM, and this decrease was prevented by BTE pretreatment in the aforesaid manner. Other major features of BTE-induced reversal of ulcerogenic agents include a significant decrease in the protein content and a marked increase in hexosamine and sialic acid content. These results suggest a major role for glutathione, an endogenous antioxidant, in the cytoprotection against ulceration afforded by BTE.

Effect of green tea (Camellia sinensis) extract on the rat diaphragm.

The effect of hot water extract of green tea on skeletal muscle and its neurotransmission was studied employing innervated and denervated rat diaphragm. Green tea extract (GTE) has a facilitatory effect at lower concentrations and a paralytic effect at higher concentrations on skeletomotor function. GTE did not have any effect on direct twitch responses or on acetylcholine (ACh) and KCl induced contractures of denervated rat diaphragm and it antagonised the submaximal paralytic effect of D-tubocurarine and decamethonium. GTE-induced facilitation and inhibition were nullified in the presence of magnesium chloride. Nifedipine, reduced GTE-induced facilitation as well as inhibition of twitch responses as a function of its concentration. It was suggested that GTE might act on Ca2+ channels at the skeletomotor junction. The effect of crude polyphenol on neuromuscular junctions was found to be similar to that of GTE. Therefore, it is suggested that the crude polyphenol content of GTE was the active constituent responsible for its effect on neuromuscular junction.