Application of MEKC and monolithic CEC for the analysis of bioactive naphthoquinones in Eleutherine americana

Two microscale separation techniques for the analysis of bioactive naphthoquinones in Eleutherine americana were developed and validated. By MEKC four compounds (eleuthoside B, isoeleutherin, eleutherol and eleutherinoside A) could be determined in plant extracts using an aqueous electrolyte solution composed of 25 mM sodium tetraborate, 50 mM sodium cholate and 20% THF. CEC on a polymeric methacrylate‐based monolith with strong cationic properties showed promising results, as it additionally enabled the separation of two enantiomers, eleutherin and isoeleutherin. The mobile phase for CEC experiments comprised 3 mM ammonium formate in a mixture of ACN and water. At an applied voltage of ?25 kV, all five markers were baseline separated in less than 12 min. Both methods were successfully validated for linearity (MEKC: R²≥0.999; CEC: R²≥0.997), sensitivity (MEKC: LOD=4–5 μg/mL; CEC: LOD=2–8 μg/mL), accuracy (MEKC: 96.5–102.7% recovery; CEC: 97.1–103.5% recovery) and precision (MEKC: σ_rel≤2.43%; CEC: σ_rel≤2.21%). The quantitative analysis of naphthoquinone derivatives in several E. americana samples showed that both methods are suitable for practical applications, because the results were well comparable to those obtained by established techniques such as HPLC.     

红葱中的新化学成分

通过正相和反相硅胶柱色以及高效液相色谱,从红葱60%乙醇提取物中分离得到3个新化合物,利用物理化学和光谱学方法鉴定了其结构,分别为9,9'-二羟基-8,8'-二甲氧基-1,1'-二甲基-1H,1H-['4,4']双[萘并(2,3-c)呋喃]-3,3'-二酮(1),6,8-二羟基-3,4-二甲氧基-1-甲基-蒽醌-2-羧酸甲酯(2),2-乙酰基-3,6,8-三羟基-1-甲基蒽醌(3).这3个化合物均能不同程度地诱导稻瘟霉菌丝变形,其最小变形质量浓度(Mini-mummorphologicaldeformationmassconcentration,MMDC)分别为145.8,50.2和124.8μg/mL.利用MTT法测定了化合物抑制人类红白血细胞株K562细胞生长的活性,化合物2的IC₅₀为49.1μg/mL.     

New bioactive constituents from eleutherine americana

Three new constituents were isolated from Eleutherine americana Merr. et K. Heyne (hong-cong) by means of silica gel, octadecyl silane (ODS) column chromatography and high-performance liquid chromatography (HPLC). They were identified as (1) 9,9′-dihydroxy-8,8′-dimethoxy-1′-dimethyl-1H, 1H′-[4,4′]bis[naphtha[2,3-c] funanyl]-3,3′-dione; (2) 6,8-dihydroxy-3,4-dimethoxy-1-methyl-anthraquin-one-2-carboxylic acid methyl ester; and (3) 2-acetyl-3,6,8-trihydroxy-1-methyl anthraquinone by the physico-chemical properties and spectral data, respectively. All three compounds showed weak activities against the growth of Pyricularia oryzea. The minimum morphological deformation concentration (MMDC) was 145.8, 50.2, and 124.8 μg/mL. Additionally, (2) also inhibited the proliferation of human erythroleukemia cancer cell line K562 with IC₅₀ value of 49.1 μg/mL. __________ Translated from Chemical Journal of Chinese Universities, 2005, 26(11) (in Chinese)     

The chemical constituents from the active fractions of Eleutherine bulbosa with their antimicrobial activity

Abstract

Six compounds including three new polyketide ones named eleubosas A-C (1–3) were isolated from the active frations of Eleutherine bulbosa. Their structures were elucidated by extensive spectroscopic methods, including NMR, MS and IR spectroscopic analyses data. All the isolates were evaluated against three pathogenic bacteria, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, and the results showed that compounds 1 and 2 displayed moderate inhibitory activities against E. coli with MIC values both 12.5?μg/mL, which are consistent with the clinical applications and need further studies.