Flavonoid glycosides from Olax mannii: Structure elucidation and effect on the nuclear factor kappa B pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Olax mannii Oliv. (Olacaceae) is among the many medicinal plants used in Nigeria for the ethnomedicinal management of both cancer and inflammation. Such plants represent potential sources of innovative therapeutic agents for the treatment of cancer and other malignant disorders. While the majority of medicinal plants exert their anticancer effects by direct cytotoxicity on tumor cells, it is important that other mechanisms through which these plants can exhibit anticancer effects are investigated. Preliminary studies indicated that Olax mannii leaves are rich sources of novel flavonoid glycosides. The detailed chemistry as well the mechanisms through which these flavonoid constituents may exert their cancer chemo-preventive and therapeutic effects are, however, not yet investigated. AIM OF THE STUDY: The aim of this study is to carry out a detailed chemical investigation of Olax mannii leaves and the effects of the isolated constituents on the nuclear factor kappa B (NF-κB) pathway. MATERIALS AND METHODS: A methanol leaf extract was subjected to various chromatographic separations to achieve isolation of flavonoid glycosides and the structures of the isolated compounds were elucidated by a combination of 1D and 2D NMR and high resolution mass spectrometry. Biological activities were assessed by measurement of cellular viability and proliferation using quantitative IncuCyte videomicroscopy, trypan blue staining and by quantification of the number of metabolically active K562 cells based on quantitation of ATP. The effect of the compounds on the inhibition of the NF-κB pathway as well as toxicity towards peripheral blood mononuclear cells to evaluate differential toxicity was also assayed. RESULTS: Chemical investigation of the methanol leaf extract of the plant material led to the isolation of three new flavonoid triglycosides, kaempferol 3-O-[α-D-apiofuranosyl-(1 → 2)-α-L-arabinofuranoside]-7-O-α-L-rhamnopyranoside (1), kaempferol 3-O-[ß-D-glucopyranosyl-(1 → 2)-α-L-arabinofuranoside]-7-O-α-L-rhamnopyranoside (2), kaempferol 3-O-[ß-D-arabinopyranosyl-(1→4)-α-L-rhamnopyranoside]-7-O-α-L-rhamnopyranoside (3), in addition to fourteen known flavonoid glycosides (4-17). Of all the tested compounds, only compound 9 (kaempferol 3-O-α-L-rhamnopyranoside) exhibited promising and specific antiproliferative activity on human K562 chronic myelogenous leukemia cells and dose-dependently inhibited NF-κB transactivation. CONCLUSION: The presence of this flavonoid glycoside and derivatives may account for the reported efficacy of Olax mannii leaf extract in the ethnomedicinal management of cancer and inflammation.

Fast determination of N-phenylpropenoyl-l-amino acids (NPA) in cocoa samples from different origins by ultra-performance liquid chromatography and capillary electrophoresis.

N-Phenylpropenoyl-l-amino acids (NPA) are among the key contributors to the astringent taste of cocoa. Two fast and easy to use methods (CE and UPLC®, both with PDA detection) for routine determination of the main NPA were developed. Crude extracts of defatted seeds were analysed by means of capillary electrophoresis leading to separation in less than 30min. Separation by means of UPLC® was much faster (<4min), however, a preceding SPE clean-up abolishes this benefit in time saving. Thus, the CE- and UPLC®-methods are comparable concerning time consumption and provide similar results. Analysis of 18 samples of raw and roasted beans from the global cocoa market originated from 12 countries and 4 continents showed a great variability of NPA content (0.7-3.6mg/g) and qualitative composition of different NPA. Anyway, all samples from cocoa beans showed a comparable NPA pattern. N-[3',4'-dihydroxy-(E)-cinnamoyl]-l-aspartic acid was the most abundant metabolite, followed by N-[4'-hydroxy-(E)-cinnamoyl]-l-aspartic acid and N-[3',4'-dihydroxy-(E)-cinnamoyl]-3-hydroxy-l-tyrosine (clovamide). The analysis of other plant organs (flowers, leaves, fruits) revealed an entirely different situation. NPA were detected in all parts of the fruit, with husk and pulp being clearly dominated by clovamide. In flowers and leaves no NPA were detected; 2-O-caffeoyltartaric acid was shown to be the major caffeic acid metabolite in leaves.

Quantitative determination of curcuminoids in Curcuma rhizomes and rapid differentiation of Curcuma domestica Val. and Curcuma xanthorrhiza Roxb. by capillary electrophoresis.

The three major curcuminoids, curcumin, demethoxycurcumin and bis-demethoxycurcumin, from Curcuma domestica Val. (Curcuma longa L.) and Curcuma xanthorrhiza Roxb. (Zingiberaceae) were fully separated and quantified in less than 5 min using a capillary zone electrophoresis method with standard fused-silica capillaries and photodiode array detection. An electrolyte solution of 20 mM phosphate, 50 mM sodium hydroxide and 14 mM beta-cyclodextrin was found to be appropriate. Quantification was performed with 3,4-dimethoxy-trans-cinnamic acid as internal standard, and the limit of detection was 0.01 mg/mL. Extraction, stabilisation during sample storage and quantification procedures were optimised and carried out with drugs and commercial curry powder from different provenances. The results were compared with the photometric method of the monograph Curcumae xanthorrhizae rhizoma of the European Pharmacopoeia.