Ahmed E. Allam

Two new acetylated flavonoid glycosides from Centaurium spicatum L

Two new acetylated flavonol glycosides, quercetin 3-O-[(2,4-diacetyl-α-l-rhamnopyranosyl)-(1→6)]-2,4-diacetyl-β-d-galactopyranoside (1) and quercetin 3-O-[(2,4-diacetyl-α-l-rhamnopyranosyl)-(1→6)]-3,4-diacetyl-β-d-galactopyranoside (2), in addition to two known acetylated quercetin glycosides quercetin 3-O-[(2,3,4-triacetyl-α-l-rhamnopyranosyl)-(1→6)-β-d-galactopyranoside (3) and quercetin 3-O-[(2,3,4-triacetyl-α-l-rhamnopyranosyl)-(1→6)-3-acetyl-β-d-galactopyranoside (4), were isolated from the aerial part of Centaurium spicatum (L.) Fritsch (Gentianaceae). Structure elucidation, especially the localization of the acetyl groups, and complete 1H and 13C NMR assignments of these biologically active compounds were carried out using one- and two-dimensional NMR measurements, including 1H- and 13C-NMR, DEPT-135, H–H COSY, HMQC and HMBC, in addition to HR-FAB/MS experiments.

Effect of polyphenols from Vicia faba L on lipase activity and melanogenesis

Abstract Two new flavonoid glycosides, kaempferol 3-O-α-L-rhamnopyranosyl (1→6) (3′′-acetyl)-β-D-galactopyranoside 1 and kaempferol 3-O-α-L-arabinopyranosyl-5-O-α-L-rhamnopyranoside 2, along with six known ones 3–8 were isolated from the flowers of Vicia faba L. (Fabaceae). Methanol extract and the isolated compounds were tested against lipase and melanogenesis inhibition activities and resulted in that compound 2 showed 53 and 77% lipase inhibition activity in concentrations of 400 and 800 μg/mL, respectively. For melanogenesis, compounds 2, 3 and 4 exhibited potent melanogenesis inhibition activity where the melanin content in melanoma cells was decreased to be about 57.5, 56 and 61%, respectively, with no obvious melanocytotoxicity. The rest of compounds showed weak to moderate activity. The results of melanogenesis inhibition activity of this study suggested the potential use of Vicia faba flowers as a skin-whitening agent and reveal the flowers to be a rich source of important phytochemicals with antilipase and melanogenesis inhibitory activity.

Lucidumol D, a new lanostane-type triterpene from fruiting bodies of Reishi (Ganoderma lingzhi)

Abstract A new lanostane-type triterpenoid, lucidumol D (1) was isolated from the fruiting bodies of Ganoderma lingzhi. Its structure was elucidated on the basis of extensive 1D- and 2D-NMR studies as well as mass spectrometry. The cytotoxicity of lucidumol D against proliferation of several cancer cells were assayed by using MTT method and the obtained result suggested selective anti-proliferative and cytotoxic effects against MCF-7, HepG2, HeLa, Caco-2, and HCT-116. In comparison to lucidumol C (2) isolated previously by our group, the structure-activity relationship indicated that carbonyl function at C-11 is necessary to enhance the cytotoxicity.

Forsskamide, a new ceramide from aerial parts of Forsskaolea tenacissima Linn.

Abstract Although the various folk medicine uses and the biological activity of Forsskaolea tenacissima L., few chemical constituents of this plant have been reported, this provoked us to make our study. Forsskamide, a new ceramide was isolated from aerial parts of F. tenacissima L. (Urticaceae). The chemical structure was established by different spectroscopic methods (1H, 13C-NMR, HMBC, HSQC, ROESY, FAB-MS and HR-FAB-MS). Forsskamide showed a moderate cytotoxic activity by (MTT) method against human colorectal carcinoma cell line (HCT-116) with IC50 33.25 μM in comparison with 5-fluorouracil IC50 26.42 μM. While, it did not show any activity against human hepatocarcinaoma cell line (HepG-2).