Arafa I. Hamed

New unusual pregnane glycosides with antiproliferative activity from Solenostemma argel

Seven new 15-keto pregnane glycosides, namely Stemmosides E--K, were isolated from Solenostemma argel. Stemmosides E--J are characterized by the occurrence of an uncommon 14 beta proton configuration while stemmosides E and F possess in addition a rare enolic function in C-16. On the other hand, stemmosides G-J display an unusual C-17 alpha side chain. Their structures were established by ESI-MS and NMR experiments. Moreover, the effect of these compounds on the VEGF-induced in Kaposis sarcoma cell proliferation was tested. Results indicated that all the compounds reduced the cell proliferation in a dose dependent manner.

Bioactive constituents of Leptadenia arborea.

The aerial part of Leptadenia arborea has been shown to contain pinoresinol (1), syringaresinol (2), leucanthemitol (3) and E-ferulaldehyde (4). These known compounds are being reported for the first time from this plant. Among them, syringaresinol has shown an inhibitory effect against acetylcholinesterase. The IC(50) (the concentration of 50% enzyme inhibition) value of this compound was 200 microg/ml.

Strong antioxidant phenolics from Acacia nilotica: Profiling by ESI-MS and qualitative–quantitative determination by LC–ESI-MS

Acacia nilotica (L.) Del. syn is a species rich in polyphenolic constituents, in which catechins are hypothesized to possess antioxidant properties and to play a role in the anti-inflammatory activity of several plants. Due to the complexity of catechin derivatives, the investigation of this class of natural compounds has been limited by difficulties in their separation. In this paper, rationalization of the phenolics occurring in the 80% EtOH extract of Acacia nilotica pods, on the basis of ESI-MS and ESI-MS/MS profiles, has been proposed. Additionally, an LC-ESI-MS qualitative study has been performed by using a C18 polar endcapped stationary phase. The fragmentation pattern obtained evidenced the presence in A. nilotica pods of galloylated catechin- and gallocatechin derivatives along with galloylated glucose derivatives. The structures were confirmed by NMR, after isolation of the pure compounds. In addition, the radical scavenging activities of extracts and pure compounds were investigated, by using the TEAC assay. Furthermore quantitative analyses were performed by LC-ESI-MS/MS, confirming the interest of this species as a rich source of very strong antioxidant principles.

A PHENOLIC CINNAMATE DIMER FROM PSORALEA PLICATA

Abstract Caryophyllene oxide, α-tocopherol, Z and E -werneria chromenes, two furanocoumarins, bakuchicin and psoralen, in addition to plicatin-B, lupeol and stigmasterol, have been isolated from the hexane-soluble extract of the aerial parts of Psoralea plicata . Plicatin-A, 3-(-3-methyl-2,3-epoxybutyl)- p -coumaric acid methyl ester and a new dimer, α- diplicatin B, were isolated from the ethyl acetate-soluble fraction. From the butanol-soluble matter, roseoside A, daidzin, isopsoralic acid- O -gluco-pyranosyl and isovitexin were isolated. Most of these compounds have been isolated from this species for the first time, although known from other plant sources.

Pregnene derivatives from Solenostemma argel leaves

Two new pregnene derivatives 14beta-15alpha-dihydroxy-delta4pregnene-3,20 dione and 3beta-14beta,15alpha-16alpha hydroxy-20-oxo-delta5pregnene-tetra-ol, in addition to alpha- and beta-amyrin and beta-sitosterol, were isolated from Solenostemma argel leaves. The structures were established by extensive spectral analysis as well as comparison with reference materials.

New steroids from Solenostemma argel leaves

Two new pregnane ester glycosides, named stemmoside A (1) and stemmoside B (2) and a third new polyhydroxy pregnane, named stemmin C (3), were isolated from Solenostemma argel leaves. The structures were achieved by extensive one- and two-dimensional NMR and MS spectroscopic analysis.

Triterpenoidal saponin glycosides from Glinus lotoides var. Dictamnoides

Abstract Three triterpenoidal saponins (glinusides A, B and C) were isolated from the n-butanol fraction of Glinus lotoides var. dictamnoides, their structures being determined by means of spectroscopic methods as 3-O-β- l -arabinopyranosyl -22-O-β- d -glucopyranosyl (4←1)-α- l -rhamnopyranosyl -15β- hydroxyhopan -6- one , 3-O-β- l -arabinopyranosyl -15-O-β- d -glucopyranosyl -22β- hydroxyhopan-6-one and 3-O-β- d -glucopyranosyl (4←1)-β- l -arabinopyranosyl -22β- hydroxyhopan-6-one , respectively.

Triterpene saponins from Glinus lotoides var. dictamnoides

Abstract Two 5b-H-hopane triterpenoidal saponins (glinusides D and E) were isolated on reinvestigation of the n -butanol soluble fraction of Glinus lotoides var. dictamnoides , in contrast to the 5a-H, 6-keto-hopane derivatives isolated from the same source. The structures of these saponins were established by extensive spectral analysis as 3- O -b- l -arabinopyranosyl-22-a- l -rhamnopyranosyl (1→4)-b- d glucopyranosyl-5b-H-16b-hydroxyhopane and 3- O -b- l -arabinopyranosyl-22- O- b- d -glucopyranosyl- (1→4)-b- d -glucopyranosyl-5b-H-16-b-hydroxyhopane, respectively.

Profiles of Steroidal Saponins from the Aerial Parts of Tribulus pentandrus, T. megistopterus subsp. pterocarpus and T. parvispinus by LC-ESI-MS/MS

INTRODUCTION Tribulus is a well-known pharmaceutical herb that has been used for a long time in the traditional Chinese and Indian systems of medicine for the treatment of various diseases. It has been found that the genus Tribulus is rich in biologically active furostane-, cholestane- and spirostane-type steroidal saponins. OBJECTIVE To develop a rapid, sensitive and accurate method based on liquid-phase extraction followed by high-performance liquid chromatography and electrospray ionisation mass spectrometry (HPLC-ESI-MS) to identify different saponins in three species of the genus Tribulus, and to quantify the compounds that are already known. METHODOLOGY After extraction from the species studied, the extracts were subjected to HPLC analyses with an XTerra® MS C(18) -column and a binary mobile phase consisting of 0.05% formic acid in water and acetonitrile, and with an ESI-MS detection in the negative ion mode. Data were acquired and processed using the Xcalibur 1.3 software. RESULTS The results exhibited that the profiles of native steroidal glycosides of both T. pentandrus and T. megistopterus subsp. pterocarpus were very similar to each other, but that of T. parvispinus was remarkably different. The fragmentation patterns provided evidence that the saponins possess spirostane-, cholestane- and furostane-type aglycones. Quantitative analyses suggested that these species are a rich source of steroidal saponins. CONCLUSION HPLC-ESI-MS/MS allowed identification of the key compounds without preparative isolation of the components from the crude extract of Tribulus species.

Benzofuran glycosides from Psoralea plicata seeds

Abstract Three new benzofuran glycosides were isolated from the N -butanol soluble fraction of Psoralea plicata seeds, together with psoralic acid (6←1)- O - β - d -glucopyranoside ( E -form), previously isolated from the aerial parts of the same plant. The structures have been determined by different spectroscopic measurements.