Maged S. Abdel-Kader

Terpenes and flavonoids from an Egyptian collection of Cleome droserifolia.

Four new sesquiterpene derivatives have been isolated from the aerial parts of Cleome droserifolia. Their structures were established as 6-di(7-hydroxy, 1, 5-epoxy germacrane) (2), 4(15)-guaiane-6-ol (3), 7α-germacra-1(10), 4(15)-diene-5β, 6α-diol (4) and 4,7,8-eudesma-triol (5). In addition, a new dolabellane diterpene derivative with the naturally rare peroxy function was identified as methyl ester of 2,18-O-diacetyl-16-O-(3-hydroxy-3-methylglutaryl)-7-hydroperoxydolabella-3,8(17)diene-2,16,18 triol (7). Two known flavonoid derivatives, pinocembrin (6) and quercetin-3-glucoside,7-rhamnoside (1) were isolated from the same source. Structures were established by spectroscopic data.

HPTLC determination of sildenafil in pharmaceutical products and aphrodisiac herbal preparations

A high-performance thin-layer chromatographic (HPTLC) method has been established for determination of sildenafil citrate in commercial products. The compounds were separated on silica gel, with CHCl3-MeOH-diethylamine, 90 + 10 + 1 (v/v), as mobile phase, and the analyte spots were quantified densitometrically at λ = 305 nm. Recovery of sildenafil citrate was 100.6 and 98.2%, for pure and spiked samples, respectively. Method precision and specificity were also validated. The method was used for determination of sildenafil in four pharmaceutical products and three aphrodisiac herbal preparations which were claimed to be totally natural. Levels of sildenafil in the pharmaceutical products ranged from 49.7 to 50.5 mg per tablet. Sildenafil was also detected in one herbal preparation at a concentration of 85.0 mg per capsule.

Iridoid glycosides from some butterflies and their larval food plants

Abstract Catalpol was the major iridoid glycoside isolated from Penstemon newberryi and P. strictus . Catalpol was found in the butterflies Euphydryas chalcedona and E. anicia whose larvae consume these plant species. P. griffinii , a possible larval host for E. anicia , did not contain catalpol, but contained other iridoid glycosides. Thessalia theona , a butterfly from Costa Rica whose larval food plant is unknown, contained only 6-β-hydroxyipolamide, a type of iridoid glycoside known only from the Verbenaceae, and not previously found in any Lepidoptera. A new iridoid glycoside, 10-bisfoliamenthoylcatalpol, was isolated from P. newberryi .

New ester and furocoumarins from the roots of Pituranthos tortuosus

Sete compostos foram isolados, a partir das fracoes soluveis em CHCl 3 , de raizes de Pituranthos tortuosos; adicionalmente manitol foi cristalizado a partir do extrato alcoolico. Usando diferentes tecnicas espectroscopicas os compostos isolados foram identificados como bergaptana, graveolana, xanthotoxinona, isopimpinela, dimetoxi aesculetina, 3-O-β-glicopiranosil estigmasterol e tambem o novo ester umbelato de 4-metoxifenila. A estrutura do novo ester foi confirmada pela sintese completa e se mostrou inativo a testes antimicrobiais e de citotoxicidade. Seven compounds were isolated from the CHCl 3 soluble fraction of the roots of Pituranthos tortuosus; in addition, mannitol was crystallized out of the total alcoholic extract. Using different spectroscopic techniques, the isolated compounds were identified as bergapten, graveolone, xanthotoxin, isopimpinellin, aesculetin dimethyl ether, stigmasterol glucoside, in addition to the new ester 4-methoxyphenylumbellate. The structure of the new ester was confirmed by total synthesis and it was found to be inactive in antimicrobial and cytotoxicity assays.

Iridoid and other glycosides from Penstemon species

Abstract Five new iridoid glucosides and three new monoterpenoid glucosides were identified from Penstemon albidus, P. cyathophorus and P. virens. N

Erythroxan diterpenes and flavonoids from Fagonia bruguieri

Abstract Aerial parts of Fagonia bruguieri afforded two new erythroxan-type diterpenes: 15,16-dihydroxy-7-oxo- cis-ent -erythrox-3-ene (fagonone) and 16- O -acetylfagonone. The structures were determined by spectroscopic methods and a single crystal X-ray diffraction study on 16- O -acetylfagonone. Five known substituted 8-methoxyflavones were also identified. This is the first reported occurrence of diterpenes in the family Zygophyllaceae and the first known ent -erythroxane.

Phytochemical and pharmacological study of Ficus palmata growing in Saudi Arabia

Phytochemical study of the aerial parts of Ficus palmata utilizing liquid-liquid fractionation and different chromatographic techniques resulted in the isolation of a new isomer of psoralenoside namely, trans-psoralenoside (5) in addition to, one triterpene: germanicol acetate (1), two furanocoumarins: psoralene (2), bergapten (3), one aromatic acid vanillic acid (4) and the flavone glycoside rutin (6). Structures of the isolated compounds were established through physical, 1D- and 2D-NMR and MS data. The total extract and fractions of the plant were examined in vivo for its possible effects as hepatoprotective, nephroprotective, antiulcer and anticoagulant activities in comparison with standard drugs. Hepatoprotective activity was assessed via serum biochemical parameters including aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transpeptidase (GGT), alkaline phosphatase (ALP) and total bilirubin. Tissue parameters such as non-protein sulfhydryl groups (NP-SH), malonaldehyde (MDA) and total protein (TP) were also measured. In addition to tissue parameters, nephroprotective effect was evaluated by measuring the serum levels of sodium, potassium, creatinine and urea. Histopathological study for both liver and kidney cells was also conducted. Antiulcer activity was explored by observing stomach lesions after treatment with ethanol. Whole blood clotting time (CT) was taken as a measure for the anticoagulant activity of the extract. Antioxidant activity of the total extract and fractions of the plant was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH) method and ascorbic acid as standard.

Two new norphenylpropanoid glucosides and hemipholin from the flowers of Ononis vaginalis

The butanol extract of the flowers of Ononis vaginalis Vahl. Symb. afforded two new norphenylpropanoid glucosides, 1-b-D-glucopyranosyl-2-(4-hydroxyphenyl) (E)-ethene (trans-vaginoside), 1-b-D-glucopyranosyl-2-(4-hydroxyphenyl) (Z)-ethene (cis-vaginoside) as well as the known flavanone C-glucoside, (+)-6-C-b-D-glucopyranosyl (2S) naringenin (hemipholin). The structures of the isolated compounds were established utilizing chemical and spectroscopic methods.

Stability-indicating densitometric HPTLC method for qualitative and quantitative analysis of hydroquinone in commercial whitening creams

High-performance thin-layer chromatographic (HPTLC) densitometric method for analysis of arbutin in commercial whitening creams was developed and validated. Aluminum-backed silica gel 60 F254 plates were used as stationary phase while methanol-chloroform-acetic acid 3.5:6:0.5 (%, v/v/v) mixture was used as mobile phase. Under these chromatographic conditions, arbutin was well separated from other ingredients. This system was found to give a well defined, sharp, and compact spot of arbutin at retention factor (RF) value of 0.40 ± 0.02. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 42.25 and 112.45 ng per spot respectively. The proposed method with high degree of precision and accuracy was employed for the analysis of arbutin both qualitatively and quantitatively in commercial whitening creams. Due to the efficiency of the method in separating arbutin from other ingredients including its degradation products, it can be applied as a stability-indicating method.

Erythroxan diterpenes from Fagonia species

Abstract Aerial parts of Fagonia bruguieri afforded a new erythroxan-type diterpene: 15,16-dihydroxy-7-β-hydroxy- cis-ent -erythrox-3-ene (7-β-hydroxyfagonene). Aerial parts of F. glutinosa yielded a series of additional new related erythroxans, most based upon a 15,16-dihydroxy- cis -ent-erythrox-3-ene structure, trivially named fagonene. These isolations extend the recently discovered presence of diterpenes in the Zygophyllaceae and provide additional examples in the ent -erythroxane diterpene series.