Biomedical subjects

S Rajasekharan

Publications and source records attributed to S Rajasekharan.

14 recordsLinked to original sources

PubMed2006

Hepatoprotective effects of Pittosporum neelgherrense Wight&Arn., a popular Indian ethnomedicine.

The stem bark of Pittosporum neelgherrense Wight&Arn. is used by the Kani and Malapandaram tribes of Kerala as an effective antidote to snake bite and for the treatment of various hepatic disorders. In the present study, the effect of the methanolic extract of the stem bark of Pittosporum neelgherrense was studied against carbon tetrachloride (CCl(4))-, d-galactosamine (D-GalN)- and acetaminophen (APAP)-induced acute hepatotoxicity in Wistar rats. Significant hepatoprotective effects were obtained against liver damage induced by all the three liver toxins, as evident from decreased levels of serum enzymes, glutamate oxaloacetate transaminase (SGOT), glutamate pyruvate transaminase (SGPT) and an almost normal architecture of the liver in the treated groups, compared to the toxin controls. Thus the present study provides a scientific rationale for the traditional use of this plant in the management of liver diseases.

Alanine Transaminase↗

PubMed2004

Enhancement in the absorption of water and electrolytes from rat intestine by Hemidesmus indicus R. Br. root (water extract).

Hemidesmus indicus root in the form of suspension in water (10 mg/ml) containing 15.5 mM NaCl, 3 mM KCl and 12 mM glucose, when injected into the ligated jejunal sac (1 ml/sac) of rat, increased the absorption of water, Na(+) and K(+) (but not glucose) from the sac. This bioactivity was present in the water extract (5 or 10 mg/sac) of the root and not in the hexane extract. In contrast, the ethanol extract decreased the absorption of water and electrolytes from the jejunal sac. The effect of water extract was not affected by heat at 100 degrees C for 30 min. Intraperitoneal administration of the water extract (50 to 200 mg/kg) was devoid of any significant effect on the jejunal absorption. Neither the root suspension nor the water extract (125-500 mg/kg) showed any significant anti-ulcer and diuretic activities in rats. The intestinal motility was also not influenced by the root (water extract) when tested in mice. The present study indicates that H. indicus root powder or its water extract can be incorporated in oral rehydrating salt solution (ORS) for increasing its anti-diarrhoeal efficacy.

Animals↗

PubMed2004

Evaluation of hepatoprotective effects of Helminthostachys zeylanica (L.) Hook against carbon tetrachloride-induced liver damage in Wistar rats.

The rhizomes of Helminthostachys zeylanica (L.) are used by the Kattunaikan tribe of Kerala, for the treatment of various hepatic disorders. In the present study, the effect of the methanolic extract of Helminthostachys zeylanica rhizomes on carbon tetrachloride (CCl4)-induced liver damage in Wistar rats was studied. The results showed that significant hepatoprotective effect was obtained against CCl4-induced liver damage, by oral administration of Helminthostachys zeylanica methanolic extract as evident from decreased levels of serum enzymes and an almost normal architecture of the liver, in the treated groups, compared to the controls. The extract was effective in increasing the choleretic activity of anaesthetised normal rats. It also shortened hexobarbitone-induced sleeping time in mice, which was increased by CCl4 treatment, besides showing significant antilipid peroxidant effect in vitro. Thus, the present study provides a scientific rationale for the traditional use of this plant in the management of liver diseases.

Animals↗

PubMed2003

A human motor control perspective to multiple manipulator modelling.

This paper describes the aspects involved in modelling a multi-robot system from a human motor control perspective. The human motor control system has a hierarchical and decentralised structure, and building a control system for a multi-robot system that attains human features would require a decomposable model. Decomposition of a complex robotic system is difficult due to the interactions between the subsystems, so these have to be first separated before the system is modelled. The proposed method of separating the interconnections is applied with the aid of fuzzy modelling to derive a fully decomposable model of two manipulator robots handling a common object.

Fuzzy Logic↗

PubMed1999

Inhibition of antigen-induced degranulation of sensitized mast cells by Trichopus zeylanicus in mice and rats.

Treatment of mice with Trichopus zeylanicus leaf resulted in inhibition of antigen-induced degranulation of sensitized peritoneal mast cells. Further, it reduced the ratio of mast cells in the peritoneal exudate cells. The plant drug treatment did not protect mice from E. coli-induced abdominal sepsis. Studies in rats using mesenteric mast cells confirmed the above mast cell-stabilizing property of T. zeylanicus. This activity was found in the butanol fraction of methanol extract of T. zeylanicus leaf. The treatment with this fraction also reduced the number of rat mesenteric mast cells. However, the in vitro treatment of the mast cells with the butanol fraction did not inhibit antigen-induced degranulation of the mast cells.

Animals↗

PubMed1998

Ethnomedical information and in vitro screening for angiotensin-converting enzyme inhibition of plants utilized as traditional medicines in Gujarat, Rajasthan and Kerala (India).

Plants utilized as traditional medicines in India have been investigated for their ability to inhibit the angiotensin converting enzyme (ACE). In total, 75 species belonging to 42 families have been investigated and new ethnomedical information has been obtained for 41 species. Four species were found to possess a high ACE inhibiting ability and were low in their tannin content.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1998

Angiotensin converting enzyme (ACE) inhibitors from Jasminum azoricum and Jasminum grandiflorum.

Bioactivity-guided fractionation of extracts of the aerial parts of Jasminum azoricum var. travancorense, using an in vitro ACE inhibition assay, led to isolation of three oligomeric, iridoid-type compounds, which were named sambacein I-III. Their structures are based on spectroscopic and chemical evidence. Similarly, fractionation of extracts of aerial parts of J. grandiflorum resulted in the isolation of the previously reported ACE inhibitor, oleacein. The IC50 values of purified ACE inhibitors were 26-36 microM. Moreover, 2-(3,4-dihydroxyphenyl)-ethanol, isoquercitrin and ursolic acid were isolated from J. grandiflorum. Sambaceins and oleacein are formed from genuine iridoid glucosides during processing of the plant material. NMR spectroscopy was used to measure the level of the ACE inhibitors in the traditional medicines prepared in Kerala from these Jasminum species.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1998

Hepatoprotective activity of Trichopus zeylanicus extract against paracetamol-induced hepatic damage in rats.

Trichopus zeylanicus extract has been evaluated for its antihepatotoxic and choleretic activities in rats. The plant leaf suspension (1000 mg/kg; wet weight) as well as its methanol extract (100 mg/kg) showed a remarkable hepatoprotective activity against paracetamol-induced hepatotoxicity as judged from the serum marker enzymes, liver histology and levels of lipid peroxides in liver. The effect of the methanol extract was found to be concentration dependent. The water and hexane extracts were almost inactive. The methanol extract (100 mg/kg) also exhibited choleretic activity in anesthetized normal rats. In short, we report here for the first time the antihepatotoxic as well as choleretic properties of T. zeylanicus.

Acetaminophen↗

PubMed1997

Aphrodisiac property of Trichopus zeylanicus extract in male mice.

Administration of Trichopus zeylanicus leaf (ethanol extract) to male mice stimulated their sexual behaviour as evidenced by an increase in number of mounts and mating performance. This activity of the ethanol extract was concentration dependent and destroyed by heat treatment at 100 degrees C for 15 min. Although oral administration of a single dose (200 mg/kg) was effective, daily administration of the extract for 6 days was found to be more effective. The pups fathered by the drug treated mice were found to be normal with reference to foetal growth, litter size and sex ratio. The water as well as n-hexane extracts of the plant leaf were inactive. The present study reveals for the first time the aphrodisiac activity of Trichopus zeylanicus, an endemic herb of India.

Animals↗

PubMed1996

Effects of Artemisia pallens Wall. on blood glucose levels in normal and alloxan-induced diabetic rats.

Oral administration of the methanol extract of the aerial parts of Artemisia pallens Wall. (used in Indian folk medicine for the treatment of diabetes mellitus) led to significant blood glucose lowering effect in glucose-fed hyperglycaemic and alloxan-induced diabetic rats. This effect of the extract was dose dependent and significant at 100 mg/kg level in glucose-fed rats. In fasted normal rats, the extract caused a moderate hypoglycaemic effect at a higher dose (1000 mg/kg). The water extract (1000 mg/kg) was inactive.

Alloxan↗

PubMed1995

In vitro screening of traditional medicines for anti-hypertensive effect based on inhibition of the angiotensin converting enzyme (ACE).

Traditional medicines reported to be used as anti-hypertensives or diuretics from different regions in the world (China, India and South America) have been investigated. The bioassay is based on inhibition of ACE, as measured from the enzymatic cleavage of the chromophore-fluorophore-labelled substrate dansyltriglycine into dansylglycine and diglycine. In total, 31 species have been investigated and the crude extracts from seven species inhibit the enzyme by more than 50%.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1994

Anaerobic pathway for conversion of the methyl group of aromatic methyl ethers to acetic acid by Clostridium thermoaceticum.

Clostridium thermoaceticum and other anaerobic acetogenic bacteria can utilize the methyl group of aromatic methyl ethers as a carbon and energy source. It has been unclear what pathway is used to metabolize this methyl group. In the work reported here, the pathway was established by identifying and quantitating the substrates, stable intermediates, and products of O-demethylation of syringic acid. By measuring the dependence of the O-demethylation reaction on purified enzymes of the acetyl-CoA pathway, it was established that CO dehydrogenase, the corrinoid/iron-sulfur protein, and methyltransferase all were required for acetyl-CoA formation. By 13C-NMR spectroscopy it was shown that the O-demethylase from C. thermoaceticum converts the methyl group of syringate to methyltetrahydrofolate (CH3-H4folate). When the reaction was conducted in the presence of CO, H2, or titanium(III), or in the absence of any electron donor, the rate of demethylation of syringic acid at pH 7.2 was approximately 15 nmol min-1 mg-1. In the absence of CO, CH3-H4folate accumulated as a stable product. When CO was added, 13CH3-H4folate was converted to [2-13C]acetyl-CoA, [2-13C]acetyl phosphate, and [2-13C]acetate. Therefore, the acetogenic O-demethylase uses H4folate as acceptor of the methyl group of phenyl methyl ethers and catalyzes the formation of CH3-H4folate. The pathway of conversion of CH3-H4folate, CO, and CoA to acetyl-CoA has been studied previously. Methyltransferase catalyzes the reaction of CH3-H4folate with the corrinoid/iron-sulfur protein to form a methylcobalt species. The nickel/iron-sulfur enzyme CO dehydrogenase then catalyzes the final steps in the formation of acetyl-CoA.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗

PubMed1992

Molecular structure of the human alcohol dehydrogenase 3 gene.

The structure and nucleotide sequence of an ADH3(1) allele, which encodes the ADH gamma 1 subunit, have been determined. The intron positions of the ADH3 gene are identical to those of the other class I and class II ADH genes. The level of nucleotide variation at the ADH3 locus is somewhat higher than those at the ADH1 and ADH2 loci.

Alcohol Dehydrogenase↗

PubMed1990

Substrate-mediated purification and characterization of a 3-hydroxybenzoic acid-6-hydroxylase from Micrococcus.

3-Hydroxybenzoic acid-6-hydroxylase from Micrococcus sp. was purified to homogeneity in a single step using the substrate-mediated interaction of the enzyme with blue-Sepharose. The enzyme was bound to the affinity matrix in the presence of 3-hydroxybenzoic acid and was eluted in its absence. The molecular weight of the purified enzyme is 70,000 with no subunit structure. The flavoenzyme required the exogenous addition of FAD for its complete activity and had a strict preference for NADH over NADPH. The activity of the enzyme was drastically inhibited by Cu2+ and Hg2+ and the inhibition was reversed by thiol reagents.

Chromatography, Ion Exchange↗