The phytochemical study on the leaves of Acanthopanax gracilistylus (Araliaceae) resulted in the discovery of a new lupane-triterpene compound, acangraciligenin S (1), and a new lupane-triterpene glycoside, acangraciliside S (2), as well as two known ones, 3α,11α-dihydroxy-lup-20(29)-en-23,28-dioic acid (3) and acankoreoside C (4). Their chemical structures were elucidated by mass, 1D- and 2D-n...

The Arabidopsis thaliana genome-sequencing project has identified the presence of 13 oxidosqualene cyclase homologs in this plant. In addition to the already identified clones, namely, CAS1 cycloartenol synthase, LUP1 lupeol synthase, and YUP8H12R.43 multifunctional triterpene synthase, two new cDNAs of the putative oxidosqualene cyclase genes, F1019.4 and T30F21.16, were obtained by polymerase...

The so-called "chemical noise background" imposes a major limit on the practical sensitivity of MALDI mass spectrometry. Typically, as the amount of material of interest subjected to MALDI analysis is reduced, the signal decreases to the point where it can no longer be differentiated from the chemical noise. Using a newly designed MALDI-ion trap mass spectrometer, we describe experiments intend...

The present study describes the fragmentation under electron ionization (EI) of gas phase serine and threonine amino acids. Ab initio methods were performed to calculate the fragmentation paths and interpret the mass spectra. The six lowest energy conformers of L-serine, L-threonine and L-allo-threonine were obtained with B3LYP, G3MP2 and MP2 methods. The adiabatic and vertical ionizat...

To study the new antifungal active triterpene glycosides of sea cucumber Holothuria scabra. Triterpene glycosides from Holothuria scabra were separated and purified by silica gel chromatography, reversed-phase silica gel chromatography and RP-HPLC. Their structures were elucidated on the basis of spectral data and chemical evidence. Three triterpene glycosides were identified as scabraside A (1...

Sweet potato varieties: Nsp, Tz and Spk obtained from Uganda were used in this study. Several phenolic compounds were identified on the basis of their mass spectra in full scan mode and the pattern of their fragmentation. The major compounds found were caffeoylquinic acid, dicaffeoylquinic acid, coumaroylquinic acid, feruloylquinic acid and caffeoylferuloylquinic acids. This is the first time t...

A group of benzimidazole analogs of sildenafil, 3-benzimidazolyl-4-methoxy-phenylsulfonylpiperazines 2-4 and 3-benzimidazolyl-4-methoxy-N,N-dimethyl- benzenesulfonamide (5), were efficiently synthesized. Compounds 2-5 were characterized by NMR and MS and contrary to the reported mass spectra of sildenafil, the spectra of the piperazine-containing compounds 2-4 showed a novel fragmentation patte...

Boophone disticha (Amaryllidaceae) is widely used in traditional medicine in southern Africa. Several alkaloids, volatile oils and fatty acids have been isolated from the plant. However, there has been no literature report of a triterpene from B. disticha. Cycloeucalenol, a cycloartane triterpene, together with its regio-isomer, was isolated from the ethyl acetate extract of the bulbs using col...

From Pseudomonas sp. PS 6.10, when grown in a casamino acid medium, a pyoverdin was isolated whose primary structure could be deduced from its mass spectrometric fragmentation pattern and amino acid analysis. It belongs to the smallest representatives of this group of siderophores comprising only six amino acids in its peptide chain. When grown in a succinate minimal medium the corresponding fe...

E-beam and gamma products from the radiolysis of aqueous solutions of (7)-metoprolol tartrate, saturated in nitrogen, are analyzed by HPLC with on-line mass and UV detectors. The structures of 10 radiolytic products common to e-beam and gamma irradiations are elucidated by comparing their fragmentation pattern to that of (7)-metoprolol. Two of the radiolytic products are also metabolites. Diffe...