Showing papers by "Alexander I. Gray published in 2010"

Activity of Scottish plant, lichen and fungal endophyte extracts against Mycobacterium aurum and Mycobacterium tuberculosis.

Abstract: With tuberculosis the leading bacterial killer worldwide and other mycobacterial diseases on the increase, the search for new antimycobacterial agents is timely. In this study, extracts from plants, lichens and fungal endophytes of Scottish provenance were screened for activity against Mycobacterium aurum and M. tuberculosis H37Rv. The best activity against M. aurum was observed for extracts of Juniperus communis roots and Cladonia arbuscula (MIC = 4 µg/mL), and a fungal endophyte isolated from Vaccinium myrtillus (MIC = 8 µg/mL). The best activity against M. tuberculosis was observed for extracts of C. arbuscula, Empetrum nigrum, J. communis roots, Calluna vulgaris aerial parts, Myrica gale roots and stems (93 to 99% inhibition at 100 µg/mL). Potent antitubercular activity (90 to 96% inhibition at 100 µg/mL) was also observed for the ethanol extracts of Xerocomus badius, Chalciporus piperatus, Suillus luteus and of endophytes isolated from C. vulgaris, E. nigrum, Vaccinium vitis-idaea and V. myrtillus. The results obtained this study provide, in part, some scientific basis for the traditional use of some of the selected plants in the treatment of tuberculosis. They also indicate that fungal endophytes recovered from Scottish plants are a source of antimycobacterial agents worthy of further investigation

The molecular shape of poly(propylenimine) dendrimer amphiphiles has a profound effect on their self assembly.

Abstract: The shape of dendrimer amphiphiles has an unexpected effect on their self-assembly. A series of diaminobutane poly(propylenimine) generation 3 dendrimer (DAB-dendr-(NH(2))(16)) amphiphiles has been synthesized, bearing an average of five (PD5), three (PD3) and one (PD1) palmitoyl group(s) per dendrimer molecule. Additionally DAB-dendr-(NH(2))(16) was derivatized with a layer of poly(ethylene glycol) (PEG, degree of polymerization = 12) groups and conjugated to an average of 1 palmitoyl group at the PEG end (PPD1). A final amphiphile resulted from the conjugation of DAB-dendr-(NH(2))(16) with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-succinimidylpropionate (DSPE-PEG(3400)-SPA), i.e.: DPD5 (with 4 DSPE-PEG arms). The critical micellar concentration in aqueous media followed the trend: DPD5

Isolation and identification of three potential impurities of pholcodine bulk drug substance.

Abstract: Three previously unreported manufacturing impurities were isolated from a pholcodine mother liquor using preparative reversed-phase HPLC. The liquor was the residue remaining after recrystallisation of a production batch of pholcodine. The impurities, which are structurally related to pholcodine, were initially detected by thin-layer chromatography (TLC). Their structures were determined after separation by preparative HPLC (Econo-Prep 5 microm C18 column, 30 cm x 21.2 mm i.d.). Structure elucidation was carried out using nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy (MS) and ultra violet (UV) spectroscopy. The impurities were identified as alkylated derivatives of pholcodine possessing second 2-morpholinoethyl substituents at various positions.

Targeted isolation of alkaloid from Cyclea Peltata and determination of structural formula of Tetrandrine alkaloid based on NMR studies

Abstract: Alkaloids are group of chemical entity with proven medicinal properties. This work consolidates the procedure in isolation and structural determination of a bisbenzyl isoquinoline alkaloid from Cyclea peltata with related NMR values and data. Dried routes of Cyclea peltata was extracted using chromatographic techniques monitored using TLC and proton NMR studies. The pure compound isolated was subjected for proton NMR, carbon NMR, HSQC, HMBC, NOESY and COSY spectral experiments. Goal is to document the methods of isolation and NMR experiments involved in structural determination. The compound isolated were bisbenzyl isoquinoline alkaloid with head to head ether bond connection and identified as “Tetrandrine”. Eventhough tetrandrine is a known compound and is reported from many other plants, this time it is isolated and reported from Cyclea peltata (H.f & T). Keywords:- Cyclea peltata; bisbenzyl isoquinoline; NMR; HSQC

Boronialatenolide: A Novel Pentanortriterpene from the Aerial Parts of Boronia alata (Rutaceae).

Abstract: From the aerial parts of Boronia alata a known protolimonoid niloticin and a novel pentanortriterpene boronialatenolide have been isolated. The structure of the novel limonoid was established by extensive n.m.r. studies.