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Atta-ur-Rahman

Publications and source records attributed to Atta-ur-Rahman.

At least 55 records · Page 3Linked to original sources
PubMed2004

Kinetics and structure-activity relationship studies on pregnane-type steroidal alkaloids that inhibit cholinesterases.

The mechanism of inhibition of acetylcholinesterase (AChE, EC 3.1.1.7) and butyrylcholinesterase (BChE, EC 3.1.1.8) enzymes by 23 pregnane-type alkaloids isolated from the Sarcococca saligna was investigated. Lineweaver-Burk and Dixon plots and their secondary replots showed that the majority of these compounds, that is 1, 4, 5, 6, 9, 10, 12, 13, 15-19, and 21 were found to be noncompetitive inhibitors of both enzymes. Compounds 8, 20, 22, and 23 were determined to be uncompetitive inhibitors of BChE, while compounds 11 and 14 were found to be uncompetitive and linear mixed inhibitors of AChE, respectively. Ki values were found to be in the range of 2.65-250.0 microM against AChE and 1.63-30.0 microM against BChE. The structure-activity relationship (SAR) studies suggested that the major interaction of the enzyme-inhibitor complexes are due to hydrophobic and cation-pi interactions inside the aromatic gorge of these cholinesterases. The effects of various substituents on the activity of these compounds are also discussed in details.

Acetylcholinesterase↗
PubMed2004

Cholinesterase inhibitory and spasmolytic potential of steroidal alkaloids.

A new steroidal alkaloid, isosarcodine (1) along with four known bases, sarcorine (2), sarcodine (3), sarcocine (4) and alkaloid-C (5) were isolated from the MeOH extract of Sarcococca saligna. The structures of these alkaloids were identified by spectral data interpretation. These compounds were subjected to acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition studies, and were found to be noncompetitive inhibitors of AChE (Ki = 21.8, 90.3, 32.2, 16.0 and 50.0 microM, respectively) and uncompetitive or noncompetitive inhibitors of BChE (Ki = 8.3, 7.5, 15.6, 5.0 and 12.0 microM, respectively). The compounds (2-5) also showed dose-dependent spasmolytic activity in the rabbit jejunum intestinal preparations and also relaxed the high K+ (80 mM)-induced contraction, indicative of a calcium channel-blocking mechanism. Structure-activity relationship suggested that the nitrogen substituents at C-3 and/or C-20 of steroidal skeleton and the hydrophobic properties of the pregnane skeleton are the key structural features contributed to the inhibitory potency of these steroidal alkaloids against AChE and BChE.

Acetamides↗
PubMed2004

Isotamarixen - a new antioxidant and prolyl endopeptidase-inhibiting triterpenoid from Tamarix hispida.

A new pentacyclic triterpenoid, 3alpha-(3",4"-dihydroxy- trans-cinnamoyloxy)- D-friedoolean-14-en-28-oic acid ( 1) has been isolated along with two known compounds, rhamnocitrin ( 2) and isorhamnetin ( 3) from the aerial parts of Tamarix hispida Willd. Compound 1 was found to be a potent antioxidant. In addition, compounds 1 - 3 showed significant inhibitory activity against prolylendopeptidase (PEP).

Antioxidants↗
PubMed2004

Two new isoflavanoids from the rhizomes of Iris soforana.

Two new isoflavones 1 and 2 along with eleven known compounds 3-13, have been isolated for the first time from the rhizomes of Iris soforana. The structures of these compounds were determined on the basis of spectroscopic methods and found to be 5,3'-dihydroxy-4'-methoxy-6,7-methylenedioxyisoflavone (1) (Soforanarin A), and 5,7,5'-trimethoxy-6,3',4'-trihydroxyisoflavone (2) (Soforanarin B).

Humans↗
PubMed2004

Biotransformation of (+)-androst-4-ene-3,17-dione.

Fermentation of (+)-androst-4-ene-3,17-dione (1) with Curvularia lunata for 10 days yielded five oxidative and reductive metabolites, androsta-1,4-diene-3,17-dione (2), 17beta-hydroxyandrosta-1,4-dien-3-one (3), 11alpha-hydroxyandrost-4-ene-3,17-dione (4), 11alpha,17beta-dihydroxyandrost-4-en-3-one (5) and 15alpha-hydroxyandrosta-1,4-dien-17-one (6). The structures of these metabolites were elucidated on the basis of spectroscopic techniques. These microbially transformed products were assayed against the clinically important enzymes, tyrosinase and prolyl endopeptidase.

Androstenedione↗
PubMed2004

Cholinesterase inhibiting withanolides from Withania somnifera.

A total of two new (1, 2) and four known (3-6) withanolides were isolated from the whole plant of Withania somnifera. Their structures were elucidated on the basis of spectroscopic techniques and were characterized as 6alpha,7alpha-epoxy-3beta,5alpha,20beta-trihydroxy-1-oxowitha-24-enolide (1), 5beta,6beta-epoxy-4beta,17alpha,27-trihydroxy-1-oxowitha-2,24-dienolide (2), withaferin-A (3), 2,3-dihydrowithaferin-A (4), 6alpha,7alpha-epoxy-5alpha,20beta-dihydroxy-1-oxowitha-2,24-dienolide (5), and 5beta,6beta-epoxy-4beta-hydroxy-1-oxowitha-2,14,24-trienolide (6), respectively. Compounds 2, 3, 5, and 6 displayed inhibitory potential against butyrylcholinesterase, but only compounds 3, 4, and 6 were found to be active against acetylcholinesterase.

Cholinesterase Inhibitors↗
PubMed2003

Synthesis and in vitro leishmanicidal activity of some hydrazides and their analogues.

Twenty-one hydrazides were synthesized by treating different esters with hydrazine hydrate. Substituted hydrazides were obtained by treating hydrazides with alkyl/aryl/acyl halides. Some of these compounds exhibit potential in vitro leishmanicidal activity. The structures of all the synthesized compounds were confirmed by spectroscopic analysis.

Alkylation↗
PubMed2003

New class of steroidal alkaloids from Fritillaria imperialis.

Two members of a new class of C-nor-D-homo steroidal alkaloids, impranine (1). and dihydroimpranine (2). along with a new pyridyl-pregnane-type steroidal alkaloid, fetisinine (3). and a known base, korsevine (4). were isolated from the bulbs of Fritillaria imperialis. The structures of the compounds were established on the basis of spectroscopic techniques and some chemical transformations. Compounds 1 and 2 form a new class of steroidal alkaloids, named as "impranane."

Alkaloids↗
PubMed2003

Broncho-vasodilatory activity of fractions and pure constituents isolated from Bacopa monniera.

The present study demonstrates that various fractions and sub-fractions isolated from Bacopa monniera produced significant inhibition of carbachol-induced bronchoconstriction, hypotension and bradycardia in anaesthetized rats. All these showed more potency towards inhibition of tracheal pressure compared to either blood pressure or heart rate. The sub-sub fraction and compound 1 caused greater inhibition of tracheal pressure and heart rate compared to blood pressure. Thus, overall bioassay-directed fractionation of B. monniera improved the bronchodilatory activity in various fractions and compound 1 (2-219x) in anaesthetized rats. In vitro, the KCl-induced contraction was equally inhibited by crude extract, petroleum ether and methanol fractions on trachea suggesting bronchodilatory activity remained the same in fractions. On pulmonary artery petroleum ether, dichloromethane and methanol fractions produced 2-2.6 times more vasodilatation compared to crude extract of B. monniera. Subsequent sub-fractions failed to show the existence of broncho-vasodilatory activity, however, the CHCl(3)/MeOH sub-fraction significantly reduced the acetylcholine-induced contraction on ileum. Both the methanol fraction and CHCl(3)/MeOH sub-fraction caused marked reduction of barium chloride-, potassium chloride- and calcium chloride-induced contraction on guinea-pig ileum, indicating their interference with Ca(2+) ion movement. Thus, it may be concluded that various fractions derived from B. monniera possess broncho-vasodilatory activity, which is attributed mainly to inhibition of calcium ions.

Animals↗
PubMed2003

Saponins from Cussonia bancoensis and their inhibitory effects on nitric oxide production.

Two new triterpenoid saponins (1 and 2) were isolated from the stem bark of Cussonia bancoensis together with the known stigmasterol, ursolic acid, 23-hydroxyursolic acid (3), and 3beta-hydroxylup-20(29)-en-28-oic acid. On the basis of their spectroscopic data and on chemical transformations, the structures of the new saponins have been established as 3-O-(alpha-Ll-arabinopyranosyl)-23-hydroxyursolic acid (1) and 3-O-(beta-D-glucopyranosyl)-23-hydroxyursolic acid (2). In a nitric oxide (NO)-production bioassay, compound 3 exhibited significant NO inhibitory activity, while compounds 1 and 2 were less potent than 3.

Animals↗
PubMed2003

A new diepoxy-ent-kauranoid, rugosinin, from Isodon rugosus.

A new diterpenoid, rugosinin (1), isolated from Isodon rugosus, with absolute configuration was proved by single-crystal X-ray diffraction analysis, to be the member of a rare class of C-20/C-7 and C-20/C-14 diepoxy- ent-kauranoids. Effusanin A (2), effusanin B (3), effusanin E (4), lasiokaurin (5) and oridonin (6) were found as known constituents of the genus Isodon with C-20/C-7 epoxy function. These compounds have exhibited DNA-damaging activity in assay which employed DNA-repair deficient (RAD 52Y) and repair proficient (RAD +) yeast strains.

Crystallography, X-Ray↗
PubMed2003

New steroidal alkaloids from Sarcococca saligna.

Two new steroidal alkaloids, salonine-A [(20S)-20-(N,N-dimethylamino)-3beta-(tigloylamino)-5alpha-pregn-14-en-2beta,4beta-diol] (1), and salonine-B [(20S)-20-(N,N-dimethylamino)-3beta-methoxy-pregn-5,16-diene] (2), were isolated from the MeOH extract of Sarcococca saligna, along with a known base, alkaloid-C (3). Their structures were elucidated on the basis of spectroscopic methods. All three compounds were found to be cholinesterase inhibitors.

Alkaloids↗
PubMed2003

Emodinol, beta-glucuronidase inhibiting triterpene from Paeonia emodi.

Emodinol, a new oleane type triterpene, has been isolated from the chloroform soluble fraction of Paeonia emodi. The structure 1beta, 3beta, 23-trihydroxyolean-12-en-28-oic acid 1 has been assigned on the basis of spectral studies including 2D NMR. It showed significant beta-glucuronidase inhibitory activity. In addition benzoic acid and 3-hydroxybenzoic acid have also been reported for the first time from this species.

Glucuronidase↗
PubMed2002

New tropane alkaloids from Erythroxylum moonii.

Four new tropane alkaloids were isolated from the leaves of Erythroxylum moonii and identified as 3 alpha-isobutyryloxy-7 beta-hydroxynortropane (1), 3 alpha-hydroxy-7 beta-phenylacetoxynortropane (2), 3 alpha-cis-cinnamoyloxytropane (3), and 3 alpha-hydroxy-6 beta-(3'-hydroxy-2'-methyl-3'-phenylpropionyloxy)-7 beta-hydroxytropane (4). Other alkaloids isolated for the first time from E. moonii were 3 alpha-benzoyloxytropane, 3 alpha-phenylacetoxytropane, 3 alpha-trans-cinnamoyloxytropane, and 3 alpha-phenylacetoxy-6 beta,7 beta-dihydroxynortropane. The structures of compounds 1-4 were elucidated by spectroscopic methods.

Alkaloids↗
PubMed2002

Novel diterpene lactones from Suregada multiflora.

Two new diterpene lactones, suregadolides A (1) and B (2), were isolated from a dichloromethane extract of Suregada multiflora bark. These compounds possess a novel skeleton, which contains a cyclopropane ring bridging C-3 and C-4 of the abietane skeleton. The structures were established on the basis of one- and two-dimensional NMR and other spectroscopic studies. Compound 1 showed moderate inhibitory activity in a mutant yeast strain bioassay.

Antifungal Agents↗
PubMed2002

A new coumarin from Murraya paniculata.

A new natural product, 2'-O-ethylmurrangatin (1) was isolated along with two previously known compounds murranganone (2) and paniculatin (3) from the leaves of Murraya paniculata. The structure of compound 1 was elucidated with the help of spectroscopic studies and by chemical reactions. Compounds 2 and 3 have been found to be cholinesterase inhibitors.

Acetylcholinesterase↗
PubMed2002

Microbial transformation of danazol.

Danazol (17beta-hydroxy-17alpha-pregna-2,4-dien-20-yno-[2,3-d] isoxazole) (1) on fermentation with Fusarium lini, Aspergillus niger, and Cephalosporium aphidicola yielded 17beta-hydroxy-2-(hydroxymethyl)-17-alpha-pregn-4-en-20-yn-3-one (2) and 17beta-hydroxy-2-(hydroxymethyl)-17 alpha-pregna-1,4-dien-20-yn-3-one (3), while the fermentation of 1 with Bacillus cerus yielded compound 2 only.

Acremonium↗