Biomedical subjects

Gad G Yousef

Publications and source records attributed to Gad G Yousef.

5 recordsLinked to original sources

PubMed2006

Comparative phytochemical characterization of three Rhodiola species.

In comparison to the well-recognized adaptogenic herb Rhodiola rosea, phytochemical constituents of two other Rhodiola species (R. heterodonta and R. semenovii) were elucidated and characterized. Two major phytochemical groups; phenolic and/or cyanogenic glycosides and proanthocyanidins, were isolated and identified in the three species. Chemical similarities among the three species were observed; however, each species displayed differences in phytochemical constituents. R. heterodonta contained a newly detected phenylethanoid glycoside, heterodontoside, in addition to the known compounds tyrosol, viridoside, salidroside, and rhodiocyanoside A. Both R. heterodonta and R. rosea contained phenylethanoid/propanoid compounds that were not detected in R. semenovii. For R. semenovii, the cyanogenic glucosides rhodiocyanoside A and lotaustralin were detected. Although the three species have proanthocyanidins composed of (-)-epigallocatechin and its 3-O-gallate esters in common, the degree of polymerization greatly differed between them. In contrast to R. heterodonta and R. semenovii, R. rosea has higher molecular weight polymeric proanthocyanidins. This study resulted in the identification and isolation of phytochemical constituents for direct cross-comparison between three Rhodiola species of medicinal and pharmacological value.

Glucosides↗

PubMed2006

Chemopreventive activity of polyphenolics from black Jamapa bean (Phaseolus vulgaris L.) on HeLa and HaCaT cells.

The antiproliferative effects of 100% methanol crude extract and of Toyopearl and silica gel fractions from the seed coats of black Jamapa beans (Phaseolus vulgaris L.) were evaluated using HeLa, human adenocarcinoma cells, and HaCaT, human premalignant keratinocytes. The 100% methanol crude extract [172.2 microM equiv of (+)-catechin] increased adhesion of HeLa cells; however, 3- and 5-fold higher concentrations decreased the number of cells attached as a function of the treatment time. The highest concentration tested diminished the cell adhesion until 40% (after 24 h) to almost 80% (after 72 h). The IC50 values showed that the 100% methanol crude extract was the most effective inhibitor of HeLa cell proliferation, even when it was dissolved in dimethylsulfoxide (DMSO) [34.5 microM equiv of (+)-catechin] or in medium [97.7 microM equiv of (+)-catechin]. The Toyopearl 5 (TP5) fraction and silica gel 2 (SG2) fraction inhibited 60% of the HeLa cell proliferation. The IC50 was 154 microM equiv of (+)-catechin of the 100% methanol crude extract on HaCaT cells. Toyopearl fractions TP4 and TP6 significantly inhibited HaCaT cell proliferation, but the silica gel fractions did not have a significant effect. The 100% methanol crude extract (35 microg of dry material/mL) decreased the number of HeLa cells in the G0/G1 phase from 68.9% (for control cells) to 51.4% (for treated cells) and increased apoptosis (2.9 and 21.2% for control and treated cells, respectively). The results indicated that black Jamapa beans could be a source of polyphenolic compounds, which have an inhibitory effect toward HeLa cancer cells but are less aggressive on HaCaT premalignant cells.

Anticarcinogenic Agents↗

PubMed2005

Characterization of polyphenolics in the seed coat of Black Jamapa bean (Phaseolus vulgaris L.).

The common bean contains phytochemicals, including phenolic compounds, which can provide health benefits to the consumer. Our objective was to characterize the polyphenolic compounds present in the seed coat of Black Jamapa bean and to test fractionation methods that permit the recovery of polyphenolics in their naturally occurring forms. A 100% methanol extract from seed coats was subjected to different chromatographic fractionation methods. Analysis by HPLC-MS revealed that a better separation of phytochemicals was achieved using direct silica gel fractionation, which allowed more accurate identification of compounds, especially of the flavonols. Anthocyanins, flavanol monomers, and heterogeneous flavanol oligomers up to hexamers were detected. To our knowledge, this is the first time that myricetin glycoside and proanthocyanidin oligomers containing (epi)-gallocatechin have been reported in the black bean. The fractionation methods used in this study produced large quantities of natural mixtures of flavonoids suitable for testing bioactivity and phytochemical interactions.

Anthocyanins↗

PubMed2005

Sorting out bioactivity in flavonoid mixtures.

Natural polyphenolic compounds, including flavonoids, which are synthesized by plants, have repeatedly been linked to multiple health benefits, but specific bioactive compounds or individualized roles have been difficult to interpret or to assign. This limitation has prevented the development of robust dietary recommendations. This paper describes a plant-cell-culture production approach that provides uniform yields of abundant natural mixtures of flavonoids from small molecules to high molecular weight oligomers and polymers. The flavonoids correspond to compounds produced in nature by the same plant genotypes; but, through elicitation tactics, the levels and the profiles of the flavonoid yield can be enhanced, and isolation from cell cultures is more rapid and streamlined than isolation from in vivo plant tissues. Introduction of (14)C sucrose to the cell-culture medium enabled the recovery and the identification of biolabeled flavonoid mixtures, which could be easily tracked in serum of rats after gavage. The biolabeled materials are now being investigated to determine tissue localization, structures of bioactive components, and the interactions between flavonoid components that contribute to bioactive potential.

Animals↗

PubMed2004

Biosynthesis and characterization of 14C-enriched flavonoid fractions from plant cell suspension cultures.

A range of radiolabeled anthocyanins, proanthocyanidins, and other flavonoids were accumulated by cell suspension cultures of two plant species, ohelo (Vaccinium pahalae) and grape (a Vitis hybrid, Bailey Alicant A), after providing uniformly labeled [(14)C]sucrose to the medium. Approximately 15% of administered label was recovered in a series of flavonoid-rich fractions varying in composition. Anthocyanins, and monomers to oligomers of proanthocyanidins, were labeled effectively and characterized from both species. Most of the proanthocyanidin oligomers were based on the flavan-3-ols (+)-catechin and (-)-epicatechin. Cyanidin and peonidin glycosides were the dominant forms of anthocyanins in both species. Whereas the predominant form of flavonoids identified from ohelo cell cultures was proanthocyanidins, grape cell cultures produced mostly anthocyanins. The labeled phytochemicals were produced for use in subsequent in vivo animal feeding studies to gauge their bioavailability and accumulation in target organs.

Anthocyanins↗