Discovery of a Natural Product That Binds to the Mycobacterium tuberculosis Protein Rv1466 Using Native Mass Spectrometry.

Elucidation of the mechanism of action of compounds with cellular bioactivity is important for progressing compounds into future drug development. In recent years, phenotype-based drug discovery has become the dominant approach to drug discovery over target-based drug discovery, which relies on the knowledge of a specific drug target of a disease. Still, when targeting an infectious disease via a high throughput phenotypic assay it is highly advantageous to identifying the compound's cellular activity. A fraction derived from the plant Polyalthia sp. showed activity against Mycobacterium tuberculosis at 62.5 µge/µL. A known compound, altholactone, was identified from this fraction that showed activity towards M. tuberculosis at an minimum inhibitory concentration (MIC) of 64 µM. Retrospective analysis of a target-based screen against a TB proteome panel using native mass spectrometry established that the active fraction was bound to the mycobacterial protein Rv1466 with an estimated pseudo-Kd of 42.0 ± 6.1 µM. Our findings established Rv1466 as the potential molecular target of altholactone, which is responsible for the observed in vivo toxicity towards M. tuberculosis.

Isotopic profiling of seized benzylpiperazine and trifluoromethylphenylpiperazine tablets using δ13C and δ15N stable isotopes.

This paper demonstrates the use of isotopic analysis of 23 benzylpiperazine (BZP) and trifluoromethylphenylpiperazine (TFMPP) containing tablets seized on two independent occasions by the Northern Territory (NT) Police, Australia. Isolation (High Performance Liquid Chromatography (HPLC)) of BZP and TFMPP followed by Isotope Ratio Mass Spectrometry (IRMS) (carbon and nitrogen stable isotopes) analysis was performed. Results are presented for δ13C and δ15N values of the respective piperazine analogues. The isotopic data and statistical analysis suggest a common source of manufacture for the BZP samples but suggest different sources for the TFMPP isolated from the corresponding BZP containing tablets investigated. The use of IRMS in this case study demonstrated the ability to obtain information regarding the BZP/TFMPP sources unattainable via conventional chemical analysis.

Precursor discrimination of designer drug benzylpiperazine using δ13C and δ15N stable isotopes.

Advances in analytical technology and emerging techniques have resulted in the increased exploitation of chemical and isotopic profiling for source linkage/discrimination of illicit drugs for forensic purposes. Although not routinely used for illicit drug investigations, such information has been obtained and its application demonstrated through the use of isotope ratio mass spectrometry (IRMS). There is a solid platform of research available relating to the isotopic analysis of methylenedioxymethamphetamine (MDMA) and methamphetamine (MA), however with the recently flourishing designer drug market it was of interest to examine the isotopic profiles of the popular 'party drug' benzylpiperazine hydrochloride (BZP·HCl). A preliminary analysis of δ13C and δ15N isotopic ratios in BZP·HCl products and corresponding synthetic intermediates (piperazine·HCl) synthesized in-house from three different precursor suppliers was conducted using IRMS. Analysis of the δ13C and δ15N isotopic data indicated that discrimination and correct grouping of all the intermediates and some of the product samples examined in this study were achievable.

Evaluation of cytotoxic activity of patriscabratine, tetracosane and various flavonoids isolated from the Bangladeshi medicinal plant Acrostichum aureum.

CONTEXT: Acrostichum aureumL. (Pteridaceae), a mangrove fern, has been used as a Bangladeshi traditional medicine for a variety of diseases including peptic ulcer. OBJECTIVE: Isolation and structural elucidation of cytotoxic secondary metabolites from the methanol extract of the aerial parts of A. aureum. MATERIALS AND METHODS: Compounds were isolated using HPLC. The compound structures were elucidated by 1D and 2D NMR, MS and other spectroscopic methods using published data. The compounds were tested for their cytotoxic activity against healthy and cancer cells using the MTT assay. Active compounds were further evaluated for apoptosis-and necrosis-inducing potential against gastric cancer cells (AGS) using the FITC Annexin V apoptosis assay. RESULTS AND DISCUSSION: Seven known compounds, patriscabratine, tetracosane and 5 flavonoids (quercetin-3-O-ß-d-glucoside, quercetin-3-O-ß-d-glucosyl-(6→1)-α-l-rhamnoside, quercetin-3-O-α-l-rhamnoside, quercetin-3-O-α-l-rhamnosyl-7-O-ß-d-glucoside and kaempferol) were isolated. Patriscabratine was found moderately cytotoxic against AGS, MDA-MB-231 and MCF-7 cells with IC(50) values ranging from 69.8 to 197.3 µM. Tetracosane showed some cytotoxic activity against AGS, MDA-MB-231, HT-29 and NIH 3T3 cells with IC(50) values ranging from 128.7 to >250 µM. Patriscabratine and tetracosane displayed an apoptotic effect (10%) on AGS cells within 24 h which was increased (20%) after 48 h, and was comparable to, if not greater, than the positive control, cycloheximide. CONCLUSION: Except for quercetin-3-O-ß-d-glucoside and kaempferol; compounds were isolated for the first time from this plant and evaluated for their cytotoxic activity. The results highlight the potential of this plant as a source of bioactive compounds and provide a rationale for its traditional use in peptic ulcer treatment.

Detection of intermittent sewage pollution in a subtropical, oligotrophic, semi-enclosed embayment system using sterol signatures in sediments.

A field study was conducted to investigate sewage inputs at popular anchorages in Moreton Bay, a sub-tropical, semienclosed embayment system in Southeast Queensland, Australia. Sterol biomarkers were quantified in sediments revealing low levels over a spatial and temporal scale consistent with a shallow, oligotrophic, highly dynamic, sand dominated system. Despite low concentrations (ng/g) and high variability, relevant sterol/stanol pairs remained well-correlated and were successful in identifying an unexpected once-off pollution event from a point source at Moreton Bay Island. During this incident, the main human sewage biomarker, coprostanol, was found at a concentration of 1.4 microg/g, with a coprostanol/5alpha-cholestanol ratio of 3.2. Other than this one incident, sterol levels were consistently low even when anchorages were at full capacity. Thus, sewage from recreational vessels was found to have very little effect on sediment quality at anchorages in Moreton Bay and Gold Coast Broadwater.