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Aim To establish an in vitro fluorescence spectrophotometry based on the end-product malondialdehyde(MDA)for evaluating hydroxyl radical-scavenging ability, and compare the advantages and disadvantages of fluorescence and visible methods.Methods The reaction time, temperature, and the concentration of key reactant deoxyribose were investigated and optimized respectively.Under different solvent conditions, sensitivity and the measurement window of two methods were compared.The hydroxyl radical scavenging ability of tanshinone I was determined by these two methods.Results The optimal temperature and time was 37 °C and 60 min, and the concentration of deoxyribose was 2.8 mmol·L-1.The limit of detection for the fluorescence method(4.49 nmol·L-1)was much lower than that of the visible spectrophotometry(39.15 nmol·L-1).The ratio of model/control(the measurement window)of the fluorescence method was much larger than that of visible spectrophotometry in both the aqueous system and the organic system(containing DMSO).Within the concentrations of 62.5 mg·L-1-1 000 mg·L-1, tanshinone I showed scavenging ability on hydroxyl radicals in a concentration-dependent manner using the fluorescence method, but the visible method could not.Conclusions In contrast to visible method, fluorescence method has the advantages of higher sensitivity and stronger anti-interference ability to the color of test substance and the specificity of solvents.By virtue of large measurement window, it can be applied to evaluating the effect of fat-soluble test substances.
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OBJECTIVE@#To evaluate in vitro antioxidant and apoptotic activities of Cyperus rotundus (C. rotundus).@*METHODS@#The phytochemical study and the antioxidant activities of both methanol and aqueous extracts from C. rotundus aerial part were determined. In addition, these extracts were also investigated for their cytotoxic and apoptotic activities. The major compound of the methanol extract was isolated. Both methanol and aqueous extracts (300, 150, and 50 μg/mL) were evaluated for their antioxidant activity by the xanthine/xanthine oxidase assay system. However, 16, 8, and 4 mg/mL of each extract were tested to investigate their OH. formation scavenging potential. Aqueous extract (800, 400, and 200 μg/mL) and methanol extract (350, 175, and 88 μg/mL) were tested against lipid peroxidation, induced by 75 μM H2O2. The cytotoxicity (by MTT assay) and cell DNA fragmentation of both extracts were evaluated towards K562 and L1210 cell lines. The major compound was obtained from the butanol fraction of methanol extract and its structure was determined by RMN spectroscopic analysis.@*RESULTS@#The methanol and aqueous extracts showed respectively, 88% and 19% inhibition of xanthine oxidase activity. Yet, the same extracts inhibited lipid peroxidation by 61.5% and 42.0%, respectively. Both extracts inhibited OH. formation by 27.1% and 25.3%, respectively. Only methanol extract induced DNA degradation. Orientin was determined as the major compound isolated from the butanol fraction of methanol extract.@*CONCLUSIONS@#It appears that C. rotundus extracts exhibit a potential use as a natural antioxidant and an apoptosis inducer.