Quantitative HPLC determination and extraction of anthraquinones in Senna alata leaves.
A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of four anthraquinones: rhein, aloe-emodin, emodin, and chrysophanol in Senna alata leaves. The method involves the use of a TSK-gel ODS-80Tm column (5 microm, 4.6 x 150 mm) at 25 degrees C with the mixture of methanol and 2% aqueous acetic acid (70:30, v/v) as the mobile phase and detection at 254 nm. The parameters of linearity, precision, accuracy, and specificity of the method were evaluated. The recovery of the method is 100.3-100.5%, and linearity (r(2) > 0.9998) was obtained for all anthraquinones. A high degree of specificity as well as repeatability and reproducibility (relative standard deviation values less than 5%) were also achieved. The solvent for extraction of anthraquinones from S. alata leaves was examined in order to increase the anthraquinone content of the leaf extract. It was found that a solution of 5% hydrochloric acid (v/v), 5% ferric chloride (w/v), and 15% water in methanol (v/v) was capable of increasing the anthraquinone content in the leaf extract up to 1.67% (w/w).
Antifungal activity of anthraquinone derivatives from Rheum emodi.
Rhein, physcion, aloe-emodin and chrysophanol isolated from Rheum emodi rhizomes exhibited antifungal activity against Candida albicans, Cryptococcus neoformans, Trichophyton mentagrophytes and Aspergillus fumigatus (MIC 25-250 microg/ml).
Novel method for the determination of the methoxyl content in lignin by headspace gas chromatography.
The paper reports on a headspace gas chromatographic (HS-GC) method for the determination of methoxyl in lignin. The method involves the quantitive cleavage of methoxyl with hydroiodic acid (HI) to form methyl iodide in a closed headspace sample vial at 130 °C for 30 min. After HI has been added, the sample is neutralized by injecting a sodium hydroxide solution; the methyl iodide in the vial was determined by HS-GC using a flame ionization detector. The results showed that the method has an excellent measurement precision (RSD < 0.69%) and accuracy (RSD < 3.5%) for the quantification of methoxyl content in lignin. The present method is simple and accurate and can be used for the efficient determination of methoxy1 content in lignin and related materials.