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).
Antimicrobial activity of Cassia alata from Malaysia.
Ethanolic extract of Cassia alata leaves was investigated for its antimicrobial activities on several microorganisms including bacteria, yeast, dermatophytic fungi and non-dermatophytic fungi. In vitro, the extract exhibited high activity against various species of dermatophytic fungi but low activity against non-dermatophytic fungi. However, bacterial and yeast species showed resistance against in vitro treatment with the extract. The minimum inhibitory concentration (MIC) values of the extract revealed that Trichophyton mentagorphytes var. interdigitale, Trichophyton mentagrophytes var. mentagorophytes, Trichophyton rubrum and Microsporum gypseum had the MIC of 125 mg/ml, whereas Microsporum canis had the MIC of 62.5 mg/ml. The inhibition can be observed on the macroconidia of Microsporum gypseum which resulted in structural degeneration beyond repair. The mechanism of inhibition can be related to the cell leakage as observed by irregular, wrinkle shape and loss in rigidity of the macroconidia.
Studies on metabolites produced by Aspergillus terreus var. aureus. I. Chemical structures and antimicrobial activities of metabolites isolated from culture broth.
A fungus which was identified as Aspergillus terreus var. aureus showed antifungal and antibacterial activities. Through the investigation of its metabolites, six compounds (1-6) were isolated ; emodin (1), dihydrogeodin (2), questin (3), sulochrin (5), the new metabolite 2-(3-chloro-4-methyl-γ-resorcyloyl)-5-hydroxy-m-anisic acid methyl ester (4), which is a monochloro derivative of sulochrin (5), and compound (6), the chemical structure of which has not yet been clarified. Dihydrogeodin (2), sulochrin (5), 4 and 6 showed antifungal and antibacterial activities, and 6 had especially strong antifungal activity towards Trichophyton mentagrophytes.