Shaheen Faizi

Fully acetylated carbamate and hypotensive thiocarbamate glycosides from Moringa oleifera

Six new and three synthetically known glycosides have been isolated from the leaves of Moringa oleifera, employing a bioassay-directed isolation method on the ethanolic extract. Most of these compounds, bearing thiocarbamate, carbamate or nitrile groups, are fully acetylated glycosides, which are very rare in nature. Elucidation of the structures was made using chemical and spectroscopic methods, including 2D NMR techniques. Thiocarbamates showed hypotensive activity.

Two insecticidal tetranortriterpenoids from Azadirachta indica

Two new triterpenoids, 6 alpha-O-acetyl-7-deacetylnimocinol [24,25,26,27-tetra-norapotirucalla-(apoeupha)-6 alpha-acetoxy-7 alpha-hydroxy-1,14,20,22-tetraen-21,23-epoxy-3-one] (1) and meliacinol [24,25,26,27-tetranorapotirucalla-(apoeupha)-1 alpha-trimethylacryloxy-21,23-6 alpha,28-diepoxy-16-oxo-17-oxa-14,20,22-trien-3 alpha,7 alpha-diol] (2) were isolated from the methanolic extract of the fresh leaves of Azadirachta indica (neem). Their structures have been elucidated through spectral studies, including 2D-NMR (COSY-45, NOESY, HMQC and HMBC). The bioactivity of these as well as of nimocinol, reported earlier from the same source, is reported. The first compound and nimocinol showed toxicity on fourth instar larvae of mosquitoes (Aedes aegypti) with LC50 values of 21 and 83 ppm, respectively. The second compound had no effect upto 100 ppm.

Triterpenoids and phenanthrenes from leaves of Bryophyllum pinnatum

Abstract From fresh leaves of Bryophyllum pinnatum three new constituents, bryophyllol, bryophollone and bryophollenone have been isolated and their structures elucidated by spectral and chemical studies. Three new compounds, bryophynol and two phenanthrene derivatives have also been identified in the mixture. 18α-Oleanane, ψ-taraxasterol, β-arnyrin acetate and a new sterol, reported earlier as a hydrolysed product, have also been obtained, along with a mixture of α- and β-amyrins and their acetates.

Hypotensive action of coumarin glycosides from Daucus carota.

Daucus carota (carrot) has been used in traditional medicine to treat hypertension. Activity-directed fractionation of aerial parts of D. carota resulted in the isolation of two cumarin glycosides coded as DC-2 and DC-3. Intravenous administration of these compounds caused a dose-dependent (1-10 mg/kg) fall in arterial blood pressure in normotensive anaesthetised rats. In the in vitro studies, both compounds caused a dose-dependent (10-200 microg/ml) inhibitory effect on spontaneously beating guinea pig atria as well as on the K+ -induced contractions of rabbit aorta at similar concentrations. These results indicate that DC-2 and DC-3 may be acting through blockade of calcium channels and this effect may be responsible for the blood pressure lowering effect of the compounds observed in the in vivo studies.

Novel hypotensive agents, niazimin A, niazimin B, Niazicin A and Niazicin B from Moringa oleifera: isolation of first naturally occurring carbamates

Two novel hypotensive carbamate glycosides designated niazimin A 1 and niazimin B 3 and two new hypotensive mustard oil glycosides possessing the thiocarbamate group, niazicin A 5 and niazicin B 10 along with a benzaldehyde glycoside 12 have been isolated from the fresh leaves extract of Moringa oleifera employing bioassay-guided fractionation. The structures of all these glycosides have been elucidated on the basis of spectroscopic evidence (IR, UV, MS, NMR, 2D NMR) and chemical reactions. Compounds 1 and 3 appear to be the first natural products embodying the carbamate moiety. The amide bond in these compounds appears to play an important role in the hypotensive activity, since in both the carbamates and thiocarbamates it is common to those which possess hypotensive activity.

Study of the in vitro antimicrobial activity of harmine, harmaline and their derivatives

Peganum harmala L. (Zygophyllaceae), commonly known as harmal, grows wild in the semiarid regions of IndoPakistan subcontinent, Iran and Africa. Its different parts have been used in traditional systems of medicine for the treatment of a variety of human ailments (Dymock et al., 1890; Chopra et al, 1956). Peganum harmala is known to contain four main alkaloids, namely harmaline (Ci3Hi40N2) reported by Goebel, harmine (Ci3H120N2) isolated by Fritsche, harmalol (Ci2Hi20NZ) noted by Goebel and prepared by Fischer from harmaline, and peganine (C,,Hi20Nz) obtained by Merk and later found to be identical with vasicine isolated earlier by Hooper (Henry, 1949). Harmal alkaloids have been reported to possess hypotensive activity (Codding, 1983), while earlier the seeds have been shown to have a marked physiological activity (Elger, 1928) and have been used for curative purposes (El-Saad and EI-Rifaie, 1980). Preliminary work on the antimicrobial study of the crude ethanolic extract of seeds of Peganum harmala was perfomed by different groups of workers (Ross et al., 1980; Al-Sharma and co-

Antimicrobial Activity of Various Parts of Polyalthia longifolia var. pendula : Isolation of Active Principles from the Leaves and the Berries

Methanol extracts of leaves, stem, twigs, green berries, flowers, roots, root‐wood and root‐bark of Polyalthia longifolia var. pendula, were tested for their antibacterial and antifungal potentials. Bioassay monitored isolation work on the methanol extract of leaves and berries which possess promising antibacterial activity led to the isolation of seven clerodane diterpenoids, 16(R and S)‐hydroxy‐cleroda‐3,13(14)Z‐dien‐15,16‐olide (1), 16‐oxo‐cleroda‐3,13(14)E‐dien‐15‐oic acid (2), methyl‐16‐oxo‐cleroda‐3,13(14)E‐dien‐15‐oate (3), 2‐oxo‐kolavenic acid (4), 16 (R and S)‐hydroxy‐cleroda‐3,13(14)Z‐dien‐15,16‐olide‐2‐one (5), (4→2)‐abeo‐16(R and S)‐hydroxy‐cleroda‐2,13(14)Z‐dien‐15,16‐olide‐3‐al (6), 3β,16α‐dihydroxy‐cleroda‐4(18), 13(14)Z‐dien‐15,16‐olide (7), while kolavenic acid (8) and solidagonal acid (9) were obtained from the root‐wood. Diterpenoids 1 and 8 were also obtained from the root‐bark. It is the first report of the isolation of 7 and 9 from this source, and clerodane 3 was obtained as a natural product for the first time.

Isolation of nematicidal compounds from Tagetes patula L. yellow flowers: structure-activity relationship studies against cyst nematode Heterodera zeae infective stage larvae.

Bioassay-guided isolation studies on the extracts of yellow flowers of Tagetes patula L. against the Heterodera zeae were carried out to identify phytochemicals lethal to this economically important cyst nematode. In vitro investigation of a polar extract and fractions showing activity led to the isolation of phenolic compounds (flavonoids and phenolic acids). In the nonpolar extract, a few fatty acids, their methyl esters, and thiophenes (including α-terthienyl) were detected. In studies of compounds obtained commercially, α-terthienyl and gallic and linoleic acids showed 100% mortality at concentrations of 0.125% after 24 h. Assessment of structure-activity relationships revealed that an increase in the number of hydroxyl groups in phenolic acids increased the activity; with fatty acids, activity depended on chain length and the number and position of double bonds. Crude extracts of the flowers of different colors also have promising activity.

Antibacterial and Antifungal Activities of Different Parts of Tagetes patula.: Preparation of Patuletin Derivatives

Abstract The current study evaluates the antibacterial and antifungal activities of extracts from different parts of Tagetes patula. Linn. (Asteraceae), reported for the first time in a single set of experiments. In the preliminary assay, the methanol extract of the flower (JFM) was found to possess antimicrobial activity against a number of bacteria with inhibition zone diameters ranging from 9 to 20 mm, the bioassay-guided fractionation of which led to the isolation of a flavonoid patuletin (3) in high yield as the active antibacterial principle with minimum inhibitory concentration (MIC) value of 12.5 μ g/disk against Corynebacterium. spp., Staphylococcus. spp., Streptococcus. spp., and Micrococcus luteus.. Its glucoside, patulitrin (4), was found to be weakly active, except against Staphylococcus saprophyticus., Streptococcus fecalis., and Streptococcus pyogenes. with inhibition zone diameters of 11, 16, and 12 mm, respectively. The cinnamate derivative (3b) of 3 showed antibacterial activity comparable with the parent flavonoid with a MIC value of 50 μ g/disk against Corynebacterium. spp., whereas benzoate derivative (3a) was found to be devoid of any activity; both the derivatives are new compounds. Moreover, the long-chain alcohol 5, which displayed antibacterial activity in the preliminary testing, was obtained in large quantity directly from the petroleum ether extract of the involucre of the flowers.

Isolation and structure elucidation of novel hypotensive agents, niazinin A, niazinin B, niazimicin and niaziminin A + B from Moringa oleifera: the first naturally occurring thiocarbamates

Novel hypotensive principles, niazinin A 1, niazinin B 2, niazimicin 4 and niaziminin A and B 6+7, have been obtained from the ethanolic extract of the fresh leaves of Moringa oleifera, employing a bioassay-guided isolation procedure. Their structures have been elucidated through spectroscopic (including 2D NMR techniques) and chemical methods. These compounds are mustard oil glycosides which are very rare in Nature and are also the first examples of naturally occurring thiocarbamates.