Om Parkash Suri

A rational approach for the design and synthesis of 1-acetyl-3,5-diaryl-4,5-dihydro(1H)pyrazoles as a new class of potential non-purine xanthine oxidase inhibitors.

Xanthine oxidase is a complex molybdoflavoprotein that catalyses the hydroxylation of xanthine to uric acid. Fifty three analogues of 1-acetyl-3,5-diaryl-4,5-dihydro(1H)pyrazoles were rationally designed and synthesized and evaluated for in vitro xanthine oxidase inhibitory activity for the first time. Some notions about structure activity relationships are presented. Six compounds 41, 42, 44, 46, 55 and 59 were found to be most active against XO with IC(50) ranging from 5.3 μM to 15.2 μM. The compound 59 emerged as the most potent XO inhibitor (IC(50)=5.3 μM). Some of the important interactions of 59 with the amino acid residues of active site of XO have been figured out by molecular modeling.

N-(1,3-Diaryl-3-oxopropyl)amides as a new template for xanthine oxidase inhibitors.

A series of forty two N-(1,3-diaryl-3-oxopropyl)amides were synthesized via an efficient, modified Dakin-West reaction and were evaluated for in vitro xanthine oxidase inhibitory activity for the first time. Structure-activity relationship analyses have been presented. Selected active xanthine oxidase inhibitors (3r, 3s, and 3zh) were assessed in vivo to study their anti-hyperuricemic effect in potassium oxonate induced hyperuricemic mice model. Compound 3s emerged as the most potent xanthine oxidase inhibitor (IC(50)=2.45 μM) as well as the most potent anti-hyperuricemic agent. The basis of significant inhibition of xanthine oxidase by 3s was rationalized by its molecular docking into catalytic site of xanthine oxidase.

Characterization of a new rat urinary metabolite of piperine by LC/NMR/MS studies.

Potential of piperine, an active alkaloid of black and long peppers, to increase the bioavailability of drugs in humans is of great clinical significance owing to its omnipresence in food. In an attempt to further study the reported differences in its metabolism in rats and humans, a new major urinary metabolite was detected in rat urine and plasma using HPLC. The metabolite was partially purified using reverse phase column chromatography on Sephadex((R))-LH 20 and characterized as 5-(3, 4-methylenedioxy phenyl)-2E,4E-pentadienoic acid-N-(3-yl propionic acid)-amide with the help of LC/NMR/positive ESI-MS studies. Complete mass fragmentation pattern could be assigned with MS/MS studies. The metabolite has a unique structure compared to the previously reported metabolites in that it retains methylenedioxy ring and conjugated double bonds while the piperidine ring is modified to form propionic acid group. Mechanism of formation of the metabolite by oxidation and cleavage of piperidine ring is proposed. Kidney appears to be the major excretion route for piperine metabolites in rats as no metabolite could be detected in feces.

Chemical Composition of Rose Water Volatiles

Abstract A volatile concentrate obtained from rose water (ex. Rosa damascena flowers) by liquid-liquid extraction with dichloromethane was studied by GC and GC/MS. The volatiles consisted mainly of 2-phenylethanol (69.7–81.6%), linalool (1.5–3.3%), citronellol (1.8–7.2%), nerol (0.2–4.2%), geraniol (0.9–7.0%) along with rose oxides and all other characteristic minor rose compounds.

A unique immuno-stimulant steroidal sapogenin acid from the roots of Asparagus racemosus

A new steroidal sapogenin molecule 1 having unique characteristics, 21-nor and unusual C19 carboxylic acid has been isolated from the roots of Asparagus racemosus. On the basis of chemical evidence, extensive spectroscopic analysis including two dimensional (2D) NMR and X-ray studies of single crystal, the structure of 1 was determined as (1S,2R,3S,8S,9S,10S,13S,14S,16S,17R,22R,25R)-21-nor-18β,27α-dimethyl-1β,2β,3β-trihydroxy-25-spirost-4-en-19β-oic acid. 1 crystallizes in monoclinic space group P2₁ with a=9.295(2), b=11.238(2), c=11.376(2) Å; β=91.993(4)°, Z=2, D(cal)=1.344 Mg/m³. The structure was solved by direct methods and refined by full-matrix least-squares procedure to a final R-value of 0.0561 for 4064 observed reflections. 1 was tested against the type of immune responses generated during treatment in normal and immune-suppressed animals and detailed biological activity evaluation suggests it to be a potent immunostimulator.

AN UNEQUIVOCAL SYNTHESIS OF 4-METHYL-2-OXO-(2H)-PYRIDO- [1,2-a]PYRIMIDINES1*

ABSTRACT An unequivocal high yielding synthesis of 4-methyl-2-oxo-(2H)-pyrido[1,2-a]pyrimidines from N-(1,3-dioxobutyl)-2-amino pyridines/picolines/quinoline, is being reported. *RRL Communication No. 2336

Isolation and structures of ellagic acid derivatives from Euphorbia acaulis

Abstract A new ellagic acid glycoside, 3,3′-di- O -methyl ellagic acid 4′-rutinoside, along with 3,4,3′-tri- O -methyl ellagic acid 4′-rutinoside and 3,4,3′-tri- O -methyl ellagic acid have been isolated from the rhizomes of Euphorbia acaulis . The structures of these compounds have been established on the basis of spectral ( 1 H NMR, 13 C NMR, MS, IR, UV) and chemical evidence.

Ehretinine, a novel pyrrolizidine alkaloid from Ehretia aspera

Abstract The structure for ehretinine, 7- O -( p -methoxybenzoyl)-retronecanol, a new pyrrolizidine alkaloid isolated from leaves of Ehretia aspera has been established by a combination of spectroscopic and chemical methods. To our knowledge this constitutes the first report of the natural occurrence of a retronecanol ester.

A New Glycoside, 3-o-Demethylcolchicine-3-o-α-d-Glucopyranoside, from Gloriosa Superba Seeds

Abstract A new colchicine glycoside, 3-O-demethylcolchicine-3-O-α-D-glucopyranoside, has been isolated from Gloriosa superba seeds. The assigned structure has been corroborated by spectroscopic data and enzymatic hydrolysis.

Novel secopyrrolizidine alkaloids from Crotalaria verrucosa

Abstract Crotaverrine and O-acetylcrotaverrine, isolated from the seeds of C. verrucosa Linn., have been shown by spectroscopy and chemical evidence to be the macrocyclic diesters of otonecine and diastereoisomeric integerrinecic acid. Hitherto, diastereoisomeric integerrinecic acid esters were not known to occur in nature.