Ahmad A. Gharaibeh

Colchicinoids from Colchicum crocifolium Boiss.: a case study in dereplication strategies for (–)-Colchicine and related analogues using LC-MS and LC-PDA techniques

As a part of a project designed to investigate Colchicum species in Jordan, the chemical constituents of Colchicum crocifolium Boiss. (Colchicaceae) were investigated using LC-MS and LC-UV/Vis PDA. A decision tree for working with colchicinods has been developed by incorporating data from LC-UV/PDA and LC-MS. This dereplication strategy draws upon the UV/PDA spectra to classify compounds into one of four structural groups and combines this with retention time and mass spectra/molecular weight to identify the compounds. This strategy was applied on a small amount of extract (2 mg) of Colchicum crocifolium to dereplicate 10 known compounds from four different structural groups, namely (-)-demecolcine, 2-demethyl-(-)-colchicine or 3-demethyl-(-)-colchicine, N-deacetyl-(-)-colchicine, (-)-colchiciline, (-)-colchicine, beta-lumidemecolcine, 2-demethyl-beta-lumicolchicine or 3-demethyl-beta-lumicolchicine, N,N-dimethyl-N-deacetyl-beta-lumicornigerine, (-)-isoandrocymbine and (-)-autumnaline. Furthermore, a new compound was identi?ed as N,N-dimethyl-N-deacetyl-(-)-cornigerine. Three compounds, which had molecular ions at m/z 325, 340 and 374, could not be dereplicated into any obvious structural classes that have been isolated in our laboratories previously or reported in the literature.

Trace minerals status and antioxidant enzymes activities in calves with dermatophytosis.

The aim of this study was to determine the levels of trace minerals Zn, Cu, and Se, the effect of dermatophytosis on the level of thiobarbituric acid reactive substances (TBARS) as an indicator of lipid peroxidation, the status of enzymatic and nonenzymatic antioxidants, and the relationship between the mentioned trace minerals and antioxidant defense system in calves with dermatophytosis. A total of 21 Holstein calves with clinically established diagnosis of dermatophytosis and an equal number of healthy ones were included in this study. Results showed that 81% of mycotic isolates were Trichophyton verrucosum, while 19% were Trichophyton mentagrophytes. The level of Zn, Cu, Se, and glutathione (GSH) and the activity of the antioxidant enzymes, glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) were significantly (P ≤ 0.05) lower. The plasma level of TBARS was significantly (P ≤ 0.05) higher in dermatophytic calves compared to healthy controls. SOD activity was fairly correlated with serum Cu and positively correlated with serum Zn in healthy control (r = 0.68, P ≤ 0.05; r = 0.58, P ≤ 0.05) and in calves affected with dermatophytosis (r = 0.73, P ≤ 0.05; r = 0.55, P ≤ 0.05), respectively. GSH-Px activity was highly correlated with whole blood selenium (r = 0.78, P ≤ 0.05) in healthy control and dermatophytic subjects (r = 0.76, P ≤ 0.05). Our results demonstrated that in dermatophytosis, the alteration in the antioxidant enzyme activities might be secondary to changes in their cofactor concentrations.

Mixed adsorbent for cleanup during supercritical fluid extraction of three carbamate pesticides in tissues

Abstract A mixed selective adsorbent composed of 7% diol and 93% C18 has been used in a cleanup column to remove the supercritical fluid lipid extractables from tissues containing carbamate pesticides. Fatty acid and sterols observed in supercritical fluid chromatographic analysis of supercritical fluid extracts of tissues were essentially eliminated. The supercritical fluid extraction recoveries of three carbamate pesticides (Bendiocarb, Methiocarb and Carbaryl) from chicken muscle ranged from 71 to 96%.

Colchicinoids from Colchicum crocifolium Boiss. (Colchicaceae)

A new colchicinoid from Colchicum crocifolium Boiss. (Colchicaceae) was isolated and identified as N,N-dimethyl-N-deacetyl-(−)-cornigerine (5), along with four known compounds, but new to the species: (−)-colchicine (1), (−)-demecolcine (2), (−)-N-methyl-(−)-demecolcine (3) and 3-demethyl-N-methyl-(−)-demecolcine (4). All isolated compounds showed potent cytotoxicity against a human cancer cell panel.

Liquid Chromatography-Mass Spectroscopy and Liquid Chromatography-Ultraviolet/Visible Photodiode Array Analysis of Selected Colchicum Species

An in-house strategy to dereplicate colchicinoid alkaloids was recently developed by our team. It aimed at quickly identifying Colchicum constituents using LC-MS (liquid chromatography- mass spectroscopy) and LC-UV/Vis PDA (liquid chromatography-ultraviolet/ visible photodiode array) techniques. In this project, our goal was to validate the developed method through analysing the alkaloid-rich fractions of three Colchicum species that had been previously studied phytochemically using the traditional bioactivity-guided fractionation methodology. The analysed species were Colchicum tauri Siehe ex Stefanoff, Colchicum stevenii Kunth, and Colchicum tunicatum Feinbr., all belonging to the family Colchicaceae. In addition to identifying the compounds previously isolated and characterized by the traditional methodology, the new strategy succeeded in tentatively identifying a set of known compounds, but new to the species