ABSTRACT
Objective: To investigate the antioxidant activity, total phenolic and total tannin content of the pericarp and the seed of Coffea benghalensis (C. benghalensis) and Coffea liberica compared to Coffea arabica (C. arabica). Methods: The antioxidant potential, total tannin and polyphenol contents of the immature and mature seed and pericarp of C. benghalensis and Coffea liberica were quantified and compared to C. arabica. Enhanced chemiluminescence (ECL), 2,2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical absorbance capacity, Folin-Ciocalteau method and total tannin content assays were used. Results: Trolox equivalent (TE/g plant material) values obtained by ECL and DPPH methods showed loose correlation (r
ABSTRACT
OBJECTIVE@#To investigate the antioxidant activity, total phenolic and total tannin content of the pericarp and the seed of Coffea benghalensis (C. benghalensis) and Coffea liberica compared to Coffea arabica (C. arabica).@*METHODS@#The antioxidant potential, total tannin and polyphenol contents of the immature and mature seed and pericarp of C. benghalensis and Coffea liberica were quantified and compared to C. arabica. Enhanced chemiluminescence (ECL), 2,2-diphenyl-1-picrylhydrazyl (DPPH), oxygen radical absorbance capacity, Folin-Ciocalteau method and total tannin content assays were used.@*RESULTS@#Trolox equivalent (TE/g plant material) values obtained by ECL and DPPH methods showed loose correlation (r(2) = 0.587) while those measured by oxygen radical absorbance capacity assay were higher without correlation in each plant. A closer correlation was detected between the ECL method and the percentage antioxidant activity of the DPPH technique (r(2) = 0.610 7) in each species, however the immature pericarp of C. benghalensis showed much higher DPPH scavenging potential than was seen in the ECL assay. The immature pericarp of C. benghalensis expressed the highest tannin and polyphenol content, and a high polyphenol level was also detected in the immature seed of C. arabica. The immature pericarp of Bengal and Liberian coffees showed the largest amount of phenolic contents.@*CONCLUSIONS@#The obtained data highlight the potential role of C. benghalensis as a new source of natural antioxidants and polyphenols compared to C. arabica.
ABSTRACT
Among various ECL systems,such as 9,10-diphenylanthraeene,lucigenin,tris(2,2'-bipyridyl) ruthenium,peroxyoxalate,luminol,graphene,and nanocrystals,Ru(bpy)_3~(2+) ECL is one of the most widely studied ECL systems in recent years due to its broad applications in immunoassays,DNA probe assays,core-actants analysis,and aptasensors. In this review,the progress in Ru(bpy)_3~(2+) ECL has been summarized on the whole,and the future research trends have been proposed.
ABSTRACT
An electrogenerated chemiluminescence ( ECL) sensor was fabricated by employing ruthenium complex polymer as ECL signal and ionic liquid as binding reagent and a sensitive ECL method for the determination of heroin was developed. The ECL sensor was prepared by thoroughly mixing ruthenium complex polymer,graphite powder and ionic liquid,which shows good electrochemical and ECL behaviors. The detection limit for tripropylamine (TPA) was one order of magnitude lower than that observed at the paraffin modified carbon paste electrode. ECL intensity of the fabricated sensor was greatly enhanced in the presence of heroin and a sensitive ECL method was proposed for the determination of heroin based on the enhancement ECL. The ECL intensity was linear with the concentration of heroin in the range from 2. 0 ×10~(-9) mol/L to 2. 0×10~(-5) mol/L and the detection limit was 8×10~(-10) mol/L. The ECL sensor exhibited a long-term stability,fine reproducibility with relative standard deviation less than 5% for 5. 0×10~(-9) mol/L heroin in 60 continuous determinations. The developed method allows the detection of heroin in a serum sample with recovery in 94% -101%.