Publications by authors named "Ahmed Abbaskhan"

A new application of α-alkoxymethylphosphonium salts in the nucleophilic phenylation of carbonyl compounds is demonstrated. Phenylation of aldehydes, ketones and acyl halides were studied by employing α-alkoxymethyltriphenylphosphonium halides in the presence of lithium hydroxide. New application of α-alkoxymethyltriphenylphosphonium salts.

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In continuation of our work on Indian celery (Seseli diffusum (Roxb. ex Sm.) Santapau & Wagh; Umbelliferae), the fractionation of the 80% MeOH-H(2) O extract of the seeds was performed to identify the principles responsible for its folk use as an antispasmodic and diuretic.

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Three new cycloartane triterpenoids have been isolated from Astragalus bicUSPIS Fisch. Their structures were elucidated as 23(R),24(S),25( R),26(S)-16 β/23,23/26,24/25-triepoxy-26-hydroxy-9,19-cyclolanosta-3,6-dione (1), 6 α,23,24,25-tetraol-16 β-acetoxy-23(R),24(R)-9,19-cyclanosta-3-one (2), and 6 α,23,24,25-tetraol-16 β-acetoxy-23(R),24(R)-9,19-cyclolanosta-3 β- O-xyloside (3), based on their spectroscopic analysis. All cycloartane tritepenoids exhibited weak cytotoxicities against 3T3 fibroblast cells as compared to the standard drug cycloheximide.

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4'-O-[beta-D-Apiosyl(1-->2)]-beta-D-glucosyl]-5-hydroxyl-7-O-sinapylflavanone (1), 3-(4-acetoxy-3,5-dimethoxy)-phenyl-2E-propenyl-beta-D-glucopyranoside (2), 3-(4-hydroxy-3,5-dimethoxy)-phenyl-2E-propenyl-beta-D-glucopyranoside (3), 5,7-dimethoxy-4'-O-beta-D-glucopyranoside flavanone (4), 4',5-dimethoxy-7-hydroxy flavanone (5), and 5,7-dimethoxy-4'-hydroxy flavanone (6), were isolated from the organic extracts of Viscum album L. (European Mistletoe). These compounds were studied for their anti-glycation and antioxidant properties.

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Phytochemical and cytotoxicity investigations on organic solvent extracts of the aerial parts of Tinospora crispa have led to the isolation of 15 cis-clerodane-type furanoditerpenoids. Of these, nine compounds (1-9) were found to be new. Spectroscopic assignments of a previously reported compound, borapetoside A (13), were revised on the basis of HMQC and HMBC correlations.

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Five glycosides, 2-(trans-cinnamoyloxy-methyl)-1-butene-4-O-beta-D-glucopyranoside (1), 4-(6'-O-trans-cinnamoyl)-(2-hydroxymethyl-4-hydroxy-butenyl-beta-D-glucopyranoside (2), 6''-O-trans-p-coumaroyl-(4-hydroxybenzoyl)-beta-D-glucopyranoside (3), 6'-O-(4-methoxy-trans-cinnamoyl) alpha/beta-D-glucopyranose (4) 6'-O-(4''-methoxy-trans-cinnamoyl)-kaempferol-3-beta-D-glucopyranoside (7) along with six known compounds, (+)-isolariciresinol 3a-O-beta-D-glucopyranoside (8) (+)-lyoniresinol 3a-O-beta-D-glucopyranoside (9), apigenin 7-O-beta-D-glucopyranoside (10), quercetin 3-O-beta-D-glucopyranoside (11), 6'-O-cinnamoyl-alpha/beta-D-glucopyranose (6) 6'-O-p-coumaroyl-alpha/beta-D-glucopyranose (5) were isolated from the whole plant of Spiraea canescens. Some of these compounds showed potent radical scavenging activity in relevant non-physiological assays. Their structures were determined by NMR spectroscopic and CID mass spectrometric techniques.

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In the course of our study on the traditional medicines and foodstuffs used in Pakistan, we investigated the origin of Indian celery by using the analysis of the internal transcribed spacer (ITS) sequence of nuclear rDNA and a phytochemical approach. We found that the source plant of the Indian celery containing coumarin derivatives such as seselin (1), bergapten (2) and isopimpinellin (3) was not common celery, Apium graveolens. Our results suggest the source plant is Seseli diffusum even though Indian workers reported that A.

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The phytochemical investigation of the ethyl acetate extract of Hypericum thasium has led to the characterization of four benzophenone derivatives 1-4, a known benzophenone 5 and four known flavonoids, quercetin (6), quercitrin (7), isoquercetin (8), and 3, 8''-biapigenin (9). Lucigenin- and luminal-based chemiluminescence assays were employed to monitor the inhibitory activity of these compounds towards the production of reactive oxygen species (ROS) by human polymorphoneutrophils (PMNs). The assay results showed that benzophenones 1 and 3 are extracellular inhibitors of ROS production, while flavonoids 6, 8, and 9 can modulate intracellular ROS production.

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Two new phenylpropanoids were isolated from Lindelofia stylosa (Kar. and Kir.) and characterized as 4-hydroxy-N-{4-[(E)-3-(4-hydroxy-3-methoxyphenyl)prop-2-enamido]butyl}benzamide (1) and 2-[3-hydroxy-4-(4-hydroxyphenoxy)phenyl]-1-(methoxycarbonyl)ethyl (E)-3-(3,4-dihydroxyphenyl)prop-2-enoate (2).

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Three new cycloartane glycosides have been isolated from Astragalus bicuspis. They were identified as 6alpha-hydroxy-3-O-beta-xylopyranosyloxy-24,25,26,27-tetranor-9,19-cyclolanosta-16,23-lactone (1), 6alpha-hydroxy-23-methoxy-16beta,23(R)-epoxy-24,25,26,27-tetranor-9,19-cyclolanosta-3-O-beta-xyloside (2), and 23(R),24(S),25(R),26(S)-16beta/23,23/26,24/25-triepoxy-6alpha,26-dihydroxy-9,19-cyclolanosta-3-O-beta-xyloside (3), on the basis of their spectroscopic data. Two known cycloartane derivatives, 4 and 5, were also obtained from this plant.

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Two glycosides, 6'-O-(3,4-dihydroxy benzoyl)-beta-D-glucopyranosyl ester (1), and 4-O-beta-d-glucopyranoside-3-hydroxy methyl benzoate (2), along with five known compounds methyl benzoate (3), hypogallic acid (4), caffeic acid (5), paeoniflorin (6) and pikuroside (7) were isolated for the first time from a fresh water fern Salvinia molesta D.S. Mitch.

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Microbial transformation of gelomulide G (3beta,6beta-diacetoxy-8beta,14beta-epoxyabiet-13(15)-en-16,12-olide, 1) was carried out. Incubation of 1 with Aspergillus niger afforded two new metabolites, 3beta,6beta-diacetoxy-8beta,14beta-dihydroxyabiet-13(15)-en-16,12-olide (2) and 3beta,6beta-diacetoxy-14beta-hydroxyabieta-8(9),13(15)-dien-16,12-olide (3). While Cunninghamella elegans afforded the 14-epimer of 2, i.

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Two bidesmosidic saponins were isolated from Climacoptera obtusifolia (Chenopodiaceae) and their structures were determined as gypsogenin 3-O-[beta-D-xylopyranosyl-(1-->3)-beta-D-glucopyranoside]-28-O-{beta-D-glucopyranosyl} ester (1) and hederagenin 3-O-[beta-D-xylopyranosyl-(1-->3)-beta-D-glucopyranoside]-28-O-[beta-D-glucopyranosyl} ester (2), by spectroscopic methods. Two known compounds, isorhamnetin 3-O-beta-D-glucopyranoside (3), and isorhamnetin 3-O-[alpha-L-rhamnopyranosyl-(1-->6)-beta-D-glucopyranoside (4) were also isolated for the first time from this plant. Compounds 1-4 were tested in various immunomodulatory assays.

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Phytochemical investigation on the whole plants of Lindelofia stylosa (Kar. and Kir.) has led to the isolation of eight fructo-oligosaccharide cinnamate esters 1-8.

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A phytochemical investigation on the aerial parts of Lindelofia stylosa has resulted in the isolation of seven phenyl propanoids. This includes three analogs of lithospermic acid, along with rosmarinic acid and its ester derivatives. Compound 1 was identified as a new natural product.

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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.

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Two new natural products, n-butyl and isopropyl 3,5-dimethoxy-4-hydroxycinnamate were isolated from Spatoglossum variabile. Three known compounds, methyl 3,4,5-trihydroxybenzoate, 2-deoxyinosine and 9-beta-(D-ribofuranosyl)adenine were isolated for the first time from the methanolic extracts of this alga. The structure elucidations of the new compounds were carried out with the help of modern spectroscopic techniques.

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