Mehtab Parveen

Neriifolione, a triterpene from Euphorbia neriifolia

Abstract A novel triterpene, 9,19-cyclolanost-20(21)-en-24-ol-3-one, named neriifolione, and cycloartenol were isolated from the latex of Euphorbia neriifolia . Their structures were elucidated with the help of chemical and physical data ( 1 H NMR, 13 C NMR, IR and mass spectra).

Two xanthones from Garcinia mangostana

Two new xanthones, 1,5,8-trihydroxy-3-methoxy-2[3-methyl-2-butenyl] xanthone and 1,6-dihydroxy-3-methoxy-2[3-methyl-2-butenyl] xanthone were isolated alongwith the known xanthone gartanin from the leaves of Garcinia mangostana and their structures elucidated by 1H NMR, IR and mass spectral studies.

SiO2–H3BO3 promoted solvent-free, green and sustainable synthesis of bioactive 1-substituted-1H-tetrazole analogues

In the present study, a focused library of multi functionalized 1-substituted-1H-tetrazole analogues 4(a–o) were synthesized, which were typically accessed via a facile, solvent-free and green synthetic protocol. The reaction involves expeditious reusable catalyst (SiO2–H3BO3) promoted condensation between a variety of heterocyclic/aromatic amines, sodium azide and triethyl ortho-formate, eliminating the use of an environmentally toxic solvent. This new eco-friendly and sustainable protocol resulted in a remarkable enhancement in the synthetic efficiency (90–97%, yield) with high purity. This silica–boric acid catalyst is air and water stable and easy to prepare from cheap silica and boric acid. The present methodology is a green protocol offering several advantages such as an excellent yield of products, a simple operational procedure, minimizing production of chemical wastes, mild reaction conditions, a shorter reaction profile, easy preparation of the catalyst and its recyclability up to five cycles without any appreciable loss in catalytic activity. The optimization conditions achieved in the present study revealed that 2.5 mol% of the SiO2–H3BO3 catalyst under solvent-free conditions at 90 °C are the best suited conditions for the synthesis of tetrazole derivatives in excellent yields. The present protocol is applicable to a broader substrate scope (electron-rich and electron-deficient). Compounds possessing a nicotinic acid nucleus (4e, 4f, 4g) displayed strongest inhibition against AChE with IC50 values of 0.43 μM, 0.21 μM and 0.26 μM, respectively. The results revealed that the electronic effect of substituents inflicts a prominent effect on AChE activity.

A novel antimicrobial agent from the leaves of Peltophorum vogelianum (Benth.)

The methanolic extract of the leaves of Peltophorum vogelianum (Caesalpiniaceae) afforded a new phytoconstituent, 2-methoxy-4,5-dihydroxy-1(7,8-dihydroxyethylene)-8-β-D-glucuropyranoside named as peltophorumyl-β-D-glucuropyranoside (5), along with four known phytoconstituents, 1-pentatriacontanol (1), friedelin (2), β-sitosterol (3) and β-sitosterol-β-D-glucopyranoside (4), which have not been isolated previously from this plant. Their structures were established on the basis of chemical and physical evidence (IR, 1H-NMR, 13C-NMR, DEPT, HSQC, HMBC and MS). Moreover, compound 5 showed significant antimicrobial activity.

Luteolin 3′-xylosyl(1→2) glucoside from viburnum grandifolium

Abstract A novel flavone glycoside, luteolin 3′-O-β-xylosyl(1→2) glucoside, together with apigenin 7-xylosyl(1→2) glucoside has been isolated from V. grandifolium. The structure were elucidated by means of 1HNMR, 13CNMR, IR, UV and NOE spectral data.

A triterpene from Garcinia mangostana

Abstract A new triterpene, 3β-hydroxy-26-nor-9,19-cyclolanost-23-en-25-one was isolated from the leaves of Garcinia mangostana and its structure elucidated by 1H NMR and mass spectral studies.

Synthesis, characterization, DNA-binding studies and acetylcholinesterase inhibition activity of new 3-formyl chromone derivatives.

A series of new substituted 3-formyl chromone derivatives (4-6) were synthesized by one step reaction methodology by knoevenagel condensation, structurally similar to known bisintercalators. The new compounds were characterized by IR, (1)H NMR, (13)C NMR, MS and analytical data. The in vitro DNA binding profile of compounds (4-6) was carried out by absorption, fluorescence and viscosity measurements. It was found that synthesized compounds, especially compound 6 (evident from binding constant value) bind strongly with calf thymus DNA, presumably via an intercalation mode. Additionally, molecular docking studies of compounds (4-6) were carried out with B-DNA (PDBID: 1BNA) which revealed that partial intercalative mode of mechanism is operational in synthesized compounds (4-6) with CT-DNA. The binding constants evaluated from fluorescence spectroscopy of compounds with CT-DNA follows the order compound 6>compound 5>compound 4. All the compounds (4-6) were screened for acetylcholinesterase inhibition assay. It can be inferred from data, that compound (6) showed potent AChE inhibition having IC50=0.27μM, almost in vicinity to reference drug Tacrine (IC50=0.19μM).

A novel lupene-type triterpenic glucoside from the leaves of Clerodendrum inerme.

A new triterpenic glucoside, lup-1,5,20(29)-trien-3-O-β-D-glucopyranoside (4), along with three known phytoconstituents: n-octacosane, friedelin and β-amyrin, has been isolated from the leaves of Clerodendrum inerme (L.) Gaertn. (Verbenaceae). Structure elucidation was carried out on the basis of chemical and physical evidence (IR, 1H-NMR, 13C-NMR, DEPT and MS spectra). The alcoholic and aqueous extracts of the leaves of C. inerme showed significant antinociceptive activity in analgaesiometer tests.

Flavonoids from Acacia tortilis

A novel isoflavone, 5,7-dihydroxy-4′- p-methyl benzyl isoflavone 1a, and three known flavonoids apigenin, luteolin and quercetin have been isolated from the leaves of Acacia tortilis. Their structures were elucidated by chemical and physical data (IR, UV, 1H-NMR, 13C-NMR and MS spectra).

Isoflavones from Garcinia nervosa

Abstract A new isoflavone, 5,7,4′-trihydroxy-2′,3′,6′-trimethoxyisoflavone, nervosin, along with two known isoflavones, irigenin (5,7,3′-trihydroxy-6,4′,5′-trimethoxyisoflavone) and 7-methyltectorigenin(5,4′-dihydroxy-6,7-di-methoxyisoflavone) have been isolated from the leaves of Garcinia nervosa . Their structures have been elucidated on the basis of chemical and spectral evidence.