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Biomedical subjects

K L Dhar

Publications and source records attributed to K L Dhar.

At least 19 recordsLinked to original sources
PubMed2006

Synthesis and bronchodilator activity of new quinazolin derivative.

Taking lead from a naturally occurring quinazolin vasicine, a number of compounds were developed and evaluated for bronchodilator and anti-allergic activities. One of these compounds was 2,4-diethoxy-6,7,8,9,10,12-hexahydroazepino[2,1-b]quinazolin-12-one, hereinafter named 95-4, exhibited marked bronchodilator activity evaluated on contracted trachea or constricted tracheo-bronchial tree. On intestinal smooth muscle too it showed relaxant effect. Tracheal relaxant effect was not found to be mediated through beta-adrenoceptors. Cumulative dose-response study with acetylcholine and histamine indicated for its non-specific direct effect on smooth muscles. 95-4 was found to be more potent than theophylline and less to that of salbutamol on dose basis. Tested by a number of experimental models, it was found devoid of anti-allergic activity. It was also found to be free from any adverse effect. 95-4 due to its marked bronchial muscle relaxant effect can find use in conditions associated with spasm of bronchial muscles.

Alkaloids↗
PubMed2005

Isolation, characterization and biological evaluation of datura lactones as potential immunomodulators.

Phytochemical investigation of Datura quercifolia (Solanaceae) plant yielded a new datura lactone, 1beta,5alpha,12alpha-trihydroxy-6alpha,7alpha,24alpha,25alpha-diepoxy-20S,22R with-2-enolide (1), along with two known compounds, 2 and 3. The structure of 1 was established on the basis of spectral analysis, as well as by its chemical transformation into known datura lactones. These compounds have been evaluated for immunomodulatory activity by observing their effect on antibody production, T-cell and B-cell activation, and cytokine production from splenocytes. Compound 2 was found to be the most promising immunostimulator in the present study.

Animals↗
PubMed2005

Synthesis and biological evaluation of chalcones and their derived pyrazoles as potential cytotoxic agents.

A series of substituted chalcones and their corresponding pyrazoles were synthesized and evaluated for in vitro cytotoxic activity against a panel of human cancer cell lines. Out of 93 compounds screened, 8 compounds, 1s, 3i,j,n, 4i,j,n and 4s, showed marked activity. Compounds 4j,n and 4s were found to be the most promising in this study. SAR is also discussed.

Antineoplastic Agents↗
PubMed2005

Separation of 9-methoxycamptothecin and camptothecin from Nothapodytes foetida by semipreparative HPLC.

The present work describes the isolation of camptothecin and 9-methoxycamptothecin from the aerial parts of Nothapodytes foetida by semipreparative high-performance liquid chromatography because the separation of compounds by conventional procedures is tedious and cumbersome. The purity of the isolates is determined by physicochemical data and liquid chromatography-mass spectrometry.

Camptothecin↗
PubMed2000

Koelpinin-A, B and C--three triterpenoids from Koelpinia linearis.

Three new triterpenoids, designated as koelpinin-A, B and C and characterised as 28-nor-lup-12,17-dien-3 beta,16 alpha-diol,3 beta-acetoxy-28-nor-lup-12,17-dien-16 alpha-ol and 28-nor-lup-12,17-dien-3 beta-ol-16-one, respectively, together with 30-nor-lup-3 beta-ol-20-one, taraxeryl acetate and germanicol, were isolated, from the aerial parts of Koelpinia linearis. 13C-NMR shifts were assigned after performing APT and DEPT experiments.

Models, Molecular↗
PubMed2000

Structure-activity relationship of piperine and its synthetic analogues for their inhibitory potentials of rat hepatic microsomal constitutive and inducible cytochrome P450 activities.

Inhibitors of drug metabolism have important implications in pharmaco-toxicology and agriculture. We have reported earlier that piperine, a major alkaloid of black and long peppers inhibits both constitutive and inducible cytochrome P450 (CYP)-dependent drug metabolising enzymes. In the present study, an attempt has been made to prepare several novel synthetic analogues so as to relate various modifications in the parent molecule to the inhibition of CYP activities. Two types of mono-oxygenase reactions arylhydrocarbon hydroxylase (AHH) and 7-methoxycoumarin-O-demethylase (MOCD) have been studied. Inhibition studies were investigated in rat microsomal fraction prepared from untreated, 3MC- and PB- treated rat liver in vitro. Modifications were introduced into the piperine molecule: (i) in the phenyl nucleus, (ii) in the side chain and (iii) in the basic moiety. Thus, 38 compounds have been subjected to such studies, and simultaneously an attempt has also been made to arrive at the structure-activity relationship of synthetic analogues. In general, most of the inhibitory potential of the parent molecule is lost with modification in either of the three components of piperine. Saturation of the side chain resulted in significantly enhanced inhibition of CYP while modifications in the phenyl and basic moieties in few analogues offered maximal selectivity in inhibiting either constitutive or inducible CYP activities. Thus few novel analogues as CYP inactivators have been synthesized which may have important consequences in pharmacokinetics and bioavailability of drugs.

Alkaloids↗
PubMed1995

Serum zinc levels in hepatic encephalopathy.

BACKGROUND: Zinc is essential for various metabolic processes of the body. Since serum zinc levels are lowered in liver diseases, it has been postulated to be a precipitating factor for hepatic encephalopathy. METHODS: We prospectively studied serum zinc levels in consecutive patients with fulminant hepatic failure, subacute hepatic failure and chronic liver disease with encephalopathy. Serum zinc levels were correlated with various clinical and biochemical parameters and final outcome of patients. Serum zinc levels were estimated by atomic absorption spectrometry at admission and also 24 hours after recovery in survivors. RESULTS: Of the 55 patients (age 17-65 years, 35 men) studied, 30 had acute, 5 subacute and 20 chronic liver disease. Patients with hepatic encephalopathy had significantly lower serum zinc levels as compared to 20 age and sex matched controls. High serum bilirubin levels and prothrombin time showed inverse relationship with serum zinc levels. There was no relationship of serum zinc levels with age, sex, grade and duration of encephalopathy, liver size, ascites or splenomegaly. CONCLUSIONS: Hepatic encephalopathy is associated with low serum zinc levels. Recovery occurred in 17 patients despite persisting low serum zinc levels. Serum bilirubin > 23 mg/dL and prothrombin time prolongation > 12 seconds above control have inverse correlation with serum zinc level.

Adult↗
PubMed1992

Chemical investigation and anti-inflammatory activity of Vitex negundo seeds.

The CHCl3 extract of the defatted seeds of Vitex negundo exhibited anti-inflammatory activity and yielded four triterpenoids: 3 beta-acetoxyolean-12-en-27-oic acid [1], 2 alpha, 3 alpha-dihydroxyoleana-5,12-dien-28-oic acid [2], 2 beta,3 alpha-diacetoxyoleana-5,12-dien-28-oic acid [3], and 2 alpha,3 beta-diacetoxy-18-hydroxyoleana-5,12-dien-28-oic acid [5]. This is the first report of the isolation of compounds 2, 3, and 5 from a natural source.

Animals↗
PubMed1992

Septic cavernous sinus thrombophlebitis: a review of 35 cases.

Thirty-five cases of septic cavernous sinus thrombophlebitis seen over the past 5 years are reviewed. Of these 80% were secondary to infection of the medial 1/3rd of the face. In more than 2/3rds of the cases the infecting organism was Staphylococcus aureus. Even with appropriate antibiotic therapy the overall mortality was 34.3%.

Adolescent↗
PubMed1992

Acute renal failure secondary to myoglobinuria.

Acute Renal Failure (ARF) secondary to rhabdomyolysis and myoglobinuria was seen in four patients. In three, this was secondary to trauma and the fourth patient had an inflammatory myositis. All 4 patients had total recovery of renal function.

Acute Kidney Injury↗