A reliable ultrasound-assisted extraction （UAE） method combined with HPLC-UV for quantification of eight active alkaloids in fruits of Macleaya cordata （Willd） R. Br. was developed. The optimization conditions of ...A reliable ultrasound-assisted extraction （UAE） method combined with HPLC-UV for quantification of eight active alkaloids in fruits of Macleaya cordata （Willd） R. Br. was developed. The optimization conditions of UAE were obtained by using Box-Behnken design of response surface methodology. Chromatography was carried out using a Kromasil C18 column by gradient elution with 0.1% phosphoric acid aqueous solution for HPLC-UV. All calibration curves showed good linear correlation coefficients （R^2〉0.999 6） and recoveries （from 97.3% to 104.9%） were acceptable. 1,1-diphenyl-2-picrylhydrazyl （DPPH） method was employed to test the antioxidant activity of the extract from the samples. The proposed method was successfully applied to quantifying eight components in nine samples of M.cordata, and significant variations of alkaloid contents and antioxidant aetivity of the samples from different habitats were demonstrated. It presents a powerful proof for the selection of the best sources to extract eight kinds of alkaloids.展开更多
The purpose of this study was to isolate a new compound from the seeds of Combretum quadrangulare Kurz, which showed antibacterial activity. The seeds were macerated with 95% of ethanol and then purified by column chr...The purpose of this study was to isolate a new compound from the seeds of Combretum quadrangulare Kurz, which showed antibacterial activity. The seeds were macerated with 95% of ethanol and then purified by column chromatography using Avicel as the adsorbent. After that, 50% of methanol in water was used as the eluting solvent and continued to further purify by Avicel preparative layer chromatogram 2 times using 80% of methanol in water as developing solvent. MIC of pure compound was done by two fold dilution method. Muller Hinton agar was selected as the media. The new compound was found as combretin, a steroidal alkaloid, and showed antibacterial activity against Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 better than Staphylococcus aureus ATCC 25923.展开更多
Crude leaf extracts of Eucalyptus camaldulensis and Tylophora indica were evaluated for their antifeedancy against Helicoverpa armigera larvae in no-choice bioassays. Cabbage leaf-disc dipped in different concentratio...Crude leaf extracts of Eucalyptus camaldulensis and Tylophora indica were evaluated for their antifeedancy against Helicoverpa armigera larvae in no-choice bioassays. Cabbage leaf-disc dipped in different concentrations of leaf extracts was used for feeding fifth instars of H. armigera for 24 hours. Ethanol extracts from both the plant species exhibited significant feeding inhibition, activity. The effective concentrations of ethanol extracts that caused 50% reduction in larval feeding （EI50） were 6.9% for E. camaldulensis and 2.8% for T. indica, while these values of hexane extracts were 9.3% and 5.2%, respectively. Compared to the crude leaf extracts, crude alkaloids from T. indica and crude tannins from E. camaldulensis were more potent in reducing larval feedings.展开更多
基金Project(20576142) supposed by the National Natural Science Foundation of China Project(2009DFA31270) supported by the International Cooperation Project of Ministry of Science and Technology of China
文摘A reliable ultrasound-assisted extraction （UAE） method combined with HPLC-UV for quantification of eight active alkaloids in fruits of Macleaya cordata （Willd） R. Br. was developed. The optimization conditions of UAE were obtained by using Box-Behnken design of response surface methodology. Chromatography was carried out using a Kromasil C18 column by gradient elution with 0.1% phosphoric acid aqueous solution for HPLC-UV. All calibration curves showed good linear correlation coefficients （R^2〉0.999 6） and recoveries （from 97.3% to 104.9%） were acceptable. 1,1-diphenyl-2-picrylhydrazyl （DPPH） method was employed to test the antioxidant activity of the extract from the samples. The proposed method was successfully applied to quantifying eight components in nine samples of M.cordata, and significant variations of alkaloid contents and antioxidant aetivity of the samples from different habitats were demonstrated. It presents a powerful proof for the selection of the best sources to extract eight kinds of alkaloids.
文摘The purpose of this study was to isolate a new compound from the seeds of Combretum quadrangulare Kurz, which showed antibacterial activity. The seeds were macerated with 95% of ethanol and then purified by column chromatography using Avicel as the adsorbent. After that, 50% of methanol in water was used as the eluting solvent and continued to further purify by Avicel preparative layer chromatogram 2 times using 80% of methanol in water as developing solvent. MIC of pure compound was done by two fold dilution method. Muller Hinton agar was selected as the media. The new compound was found as combretin, a steroidal alkaloid, and showed antibacterial activity against Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 better than Staphylococcus aureus ATCC 25923.
文摘Crude leaf extracts of Eucalyptus camaldulensis and Tylophora indica were evaluated for their antifeedancy against Helicoverpa armigera larvae in no-choice bioassays. Cabbage leaf-disc dipped in different concentrations of leaf extracts was used for feeding fifth instars of H. armigera for 24 hours. Ethanol extracts from both the plant species exhibited significant feeding inhibition, activity. The effective concentrations of ethanol extracts that caused 50% reduction in larval feeding （EI50） were 6.9% for E. camaldulensis and 2.8% for T. indica, while these values of hexane extracts were 9.3% and 5.2%, respectively. Compared to the crude leaf extracts, crude alkaloids from T. indica and crude tannins from E. camaldulensis were more potent in reducing larval feedings.
