RP‐HPLC‐DAD method for the estimation of embelin as marker in Embelia ribes and its polyherbal formulations

Evidence‐based herbal products with assured quality are assuming importance for complementary and alternative medicine. Traditional medicines by and large are not standardized and validated to meet the new requirements. In the present study, marker (embelin)‐based standardization of a major medicinal plant, Embelia ribes and its polyherbal formulations was attempted. Conditions for the quantitative extraction of the marker compound embelin from E. ribes fruits and herbal formulations were also optimized. Reversed‐phase high‐performance liquid chromatography, coupled with diode array detection (RP‐HPLC–DAD) for the quantification of embelin was developed and validated. Satisfactory results were obtained with respect to linearity (15–250 µg/mL), LOD (3.97 µg/mL), LOQ (13.2 µg/mL), recovery (99.4–103.8%) and precision (1.43–2.87%). The applicability of the method was demonstrated with selected phytopharmaceuticals. The present method was sensitive, accurate, simple and reproducible and therefore can be recommended for marker‐based standardization, and quality assurance of E. ribes herbal formulations. Copyright © 2010 John Wiley & Sons, Ltd.     

Flavonol Glycosides from the Leaves of Embelia Keniensis

Five new flavonol glycosides characterized as syringetin 3‐O‐α‐rhamnoside‐7‐O‐β‐glucoside, syringetin 3‐O‐α‐rhamnoside‐7,4′‐di‐O‐β‐glucoside, quercetin‐7‐O‐β‐galactosyl (1→3)‐β‐galactoside, myricetin 3‐O‐α‐rhamnosyl (1→4)‐β‐galactoside and myricetin 3‐O‐β‐glucosyl (1→2)‐β‐glucoside‐7‐O‐β‐glucosyl‐(1→4)‐α‐rhamnoside have been isolated from a methanolic extract of Embelia keniensis leaves. Known flavonols isolated from the same extract included myricetin, quercetin, kaempferol, myricetin 3‐O‐α‐rhamnoside, myricetin 3‐O‐β‐glucoside, quercetin 3‐O‐α‐rhamnoside, quercetin 3‐O‐β‐glucoside, quercetin 3‐O‐β‐xyloside, isorhamnetin 3‐O‐α‐rhamnoside and myricetin 3‐O‐rutinoside. Their structures were established from extensive spectroscopic and chemical studies and by comparison with authentic samples.     

A new alkylbenzoquinone from Embelia rowlandii Gilg. (Myrsinaceae)

A new alkylbenzoquinone named embeliquinone (1) together with five known compounds, lupeol (2), 3-O-[6′-O-palmitoyl-β-d-glucosyl]-spinasta-7,22(23)-diene (3), quercetin (4), (2S,3S,4R,8E)-2-[(2′R)-2′-hydroxy-heneicosanoylamino]-heneicosane-1,3,4-triol-8-ene (5), and β-sitosterol-3-O-β-d-glucopyranoside (6) were isolated from the MeOH leaf extract of Embelia rowlandii by using repeated open column chromatography techniques. The structure of the new compound was characterized by analyses of 1D- and 2D-NMR, and MS data. Embeliquinone (1) had moderate anti-cell proliferation activity against A549 cell line with the IC₅₀ value of 21.8 μM. In addition, 1 exhibited weak antibacterial activities against Klebsiella pneumoniae and Staphylococcus aureus with an MIC value of 206.0 μM in both cases.     

Tentative characterization of phenolic compounds in three species of the genus Embelia by liquid chromatography coupled with mass spectrometry analysis

Abstract

This article illustrates the chemical characterization of phenolic compounds, of the selected species of the genus Embelia viz., Embelia ribes, Embelia tsjeriam-cottam, and Embelia basaal using liquid chromatography coupled with mass spectrometry analysis with electrospray ionization (ESI) in negative mode. The analysis of samples allowed first-time identification of different phenolic compounds, which consists of various types of flavonoids, flavonoid glycosides, organic acids, and their derivatives, benzenoids, coumarins, and stilbens in this genus. Seventy-three different phenolic compounds were identified based on the fragment ions, and over thirty unknown compounds with unique fragmentation patterns were further noted. The results of the study offer that the selected species of the genus Embelia, which is being used in centuries-old traditional medical systems, is a promising source of medicinally valuable compounds like luteolin, sinesetin, rutin, naringenin, astragalin, narcissin, vanillic acid, resveratrol, and so on.     

Single‐step isolation of embelin using high‐performance countercurrent chromatography and determination of the fatty acid composition of seeds of Embelia schimperi

Embelin (2,5‐dihydroxy‐3‐undecyl‐p ‐benzoquinone) is known for its potent anthelmintic activity, but also for wound‐healing, antidiabetic, anticonvulsant, antitumour, anti‐inflammatory, analgesic, hepatoprotective, antioxidant, antibacterial and antispermatogenic activities. A high‐performance countercurrent chromatography method was developed for the purification of embelin from an extract of the seeds of Embelia schimperi fruit. The optimized solvent system (n ‐hexane–ethylacetate–ethanol–water, 7:3:7:3) resulted in the isolation of 13.9 mg of embelin, directly from 100 mg of crude extract, in a single step within a short time (40 min). Although the compound appeared to be completely pure when analysed by ultra‐performance liquid chromatography (UPLC) with photo diode array detection, the purity was established as ~90% by UPLC–mass spectrometry. Furthermore, we report the fatty acid composition of the seeds of E. schimperi fruit. Nine fatty acids were quantified from the fruit seed extract by gas chromatography–mass spectrometry, with linoleic (46.4%), palmitic (21.5%) and oleic (19.6%) acids making up the largest proportions.