Syed Imran Hassan

Triterpenoids from the leaves of Psidium guajava

Two triterpenoids, 20beta-acetoxy-2alpha,3beta-dihydroxyurs-12-en-28-oic acid (guavanoic acid, 3), and 2alpha,3beta-dihydroxy-24-p-z-coumaroyloxyurs-12-en-28-oic acid (guavacoumaric acid, 7), along with six known compounds 2alpha-hydroxyursolic acid (1), jacoumaric acid (2), isoneriucoumaric acid (4), asiatic acid (5), ilelatifol D (6) and beta-sitosterol-3-O-beta-D-glucopyranoside (8), have been isolated from the leaves of Psidium guajava. Their structures were determined through spectroscopic methods. Compound 5 showed dose-dependent (10-500 microg/ml) spasmolytic activity in spontaneously contracting isolated rabbit jejunum preparations.

CHEMICAL CONSTITUENTS FROM THE LEAVES OF PSIDIUM GUAJAVA

Five constituents including one new pentacyclic triterpenoid guajanoic acid (1) and four known compounds β-sitosterol (2), uvaol (3), oleanolic acid (4), and ursolic acid (5) have been isolated from the leaves of Psidium guajava.The new constituent1has been characterized as 3β-p-E-coumaroyloxy-2α-methoxyurs-12-en-28-oic acid through 2D NMR techniques and chemical transformations. This is the first report of isolation of compound 3 from the genus Psidium

Triterpenoids from Psidium Guajava Leaves

Three pentacyclic triterpenoids including one new guajavanoic acid ( 2 ) and two known obtusinin ( 1 ) and goreishic acid I ( 3 ) have been isolated from the leaves of Psidium guajava . The new constituent 2 has been characterized as 2 f -hydroxy-3 g - p-E -coumaroyloxyurs-12, 18-dien-28-oic acid through 1 H-NMR and 13 C-NMR (broad band and DEPT). This is the first report of isolation of compound 1 and 3 from the genus Psidium .

A new ethylene glycol triterpenoid from the leaves of Psidium guajava

One new pentacyclic triterpenoid psidiumoic acid (5) along with four known compounds β-sitosterol (1), obtusol (2), oleanolic acid (3), and ursolic acid (4) have been isolated from the leaves of Psidium guajava. The new constituent 5 has been characterized as 2α-glycolyl-3β-hydroxyolean-12-en-28-oic acid through 2D NMR techniques. This is the first report of isolation of compound 2 from the genus Psidium.

A Rapid, Mild, Efficient, and Solvent‐Free Friedel‐Crafts Acylation of N‐Acetyltetrahydroharmine

Abstract The first solid‐phase, rapid, and mild synthesis of 10‐acyl and 12‐acyl analogues of N‐acetyltetrahydroharmine by Friedel‐Crafts acylation has been developed. The products were obtained in high overall yields. The method also results in the high‐yield synthesis of natural product jafrine.

Preparation, structure and spasmolytic activities of some derivatives of harmine series of alkaloids

Keeping in view the interesting chemistry and pharmacological importance of harmine series of bases – the β-carboline alkaloids, a number of new derivatives of tetrahydroharmine (1) and harmalol (2) have been prepared and characterized through spectral studies. Some of these derivatives showed spasmolytic activity. It was observed that all the N-acyl tetrahydroharmine derivatives are stable, not labile and no ring opening occurs in these compounds, as reported recently.

Synthesis and Antimycobacterial Activity of Some β-Carboline Alkaloids

In view of the attributed medicinal properties of β-carboline alkaloids, some new O-acyl derivatives of β-carboline alkaloid – harmol, were prepared and tested for possible antimycobacterial activity against Mycobacterium tuberculosis H37Rv.

Synthesis and antimycobacterial activity of some beta-carboline alkaloids.

In view of the attributed medicinal properties of β-carboline alkaloids, some new O-acyl derivatives of β-carboline alkaloid – harmol, were prepared and tested for possible antimycobacterial activity against Mycobacterium tuberculosis H37Rv.

Chemical Constituents of the Leaves of Psidium guajava

Five constituents including one new pentacyclic triterpenoid guajanoic acid (1) and four known compounds beta-sitosterol (2), uvaol (3), oleanolic acid (4), and ursolic acid (5) have been isolated from the leaves of Psidium guajava. The new constituent 1 has been characterized as 3beta-p-E-coumaroyloxy-2alpha-methoxyurs-12-en-28-oic acid through 2D NMR techniques and chemical transformations. This is the first report of isolation of compound 3 from the genus Psidium.

Synthesis and Antimycobacterial Activity of Someβ-Carboline Alkaloids

In view of the attributed medicinal properties of β-carboline alkaloids, some new O-acyl derivatives of β-carboline alkaloid – harmol, were prepared and tested for possible antimycobacterial activity against Mycobacterium tuberculosis H37Rv.