Antioxidant activities of ethanol extracts and fractions of Crescentia cujete leaves and stem bark and the involvement of phenolic compounds.
BACKGROUND
Antioxidant compounds like phenols and flavonoids scavenge free radicals and thus inhibit the oxidative mechanisms that lead to control degenerative and other diseases. The aim of this study was to investigate the antioxidant activity in vitro, total phenolic and flavonoid contents in ethanol extracts and fractions of Crescentia cujete leaves and stem bark.


METHODS
Crescentia cujete leaves and bark crude ethanol extract (CEE) and their partitionates petroleum ether (PEF), chloroform (CHF), ethyl acetate (EAF) and aqueous (AQF) were firstly prepared. Different established testing methods, such as 1, 1-diphenyl-2-picryl hydrazyl (DPPH) radical, ferric reducing power (FRP), and total antioxidant capacity (TAC) assays were used to detect the antioxidant activity. Further, the total yield, total phenolic (TPC) and total flavonoid contents (TFC) of CEE and all the fractions were determined. Ethanol extracts of both leaves and stem bark were also subjected to preliminary phytochemical screening to detect the presence of secondary metabolites, using standard phytochemical methods (Thin layer chromatography and spray reagents).


RESULTS
Phytochemical screening of crude ethanol extract of both leaves and stem bark revealed the presence of steroids, flavonoids, saponins, tannins, glycosides and terpenoids. All the fractions and CEE of leaves and bark exhibited antioxidant activities, however, EAF of leaves showing the highest antioxidant activity based on the results of DPPH, FRP and TAC assay tests. The above fraction has shown the significant DPPH scavenging activity (IC50 = 8.78 μg/ml) when compared with standard ascorbic acid (IC50 =7.68 μg/ml). The TAC and FRP activities increased with increasing crude extract/fractions content. The TPC (371.23 ± 15.77 mg GAE/g extract) and TFC (144.64 ± 5.82 mg QE/g extract) of EAF of leaves were found significantly higher as compared to other solvent fractions for both leaves and bark. TPC were highly correlated with the antioxidant activity (R2 = 0.9268 and 0.8515 in DPPH test for leaves and bark, respectively).


CONCLUSIONS
The results of the study show that leaves of C. cujete possesses significant free radical scavenging properties compared with stem bark and a clear correlation exists between the antioxidant activity and phenolic content.
Nandita
N
Das
Md Ekramul
ME
Islam
Nusrat
N
Jahan
Mohammad Saiful
MS
Islam
Alam
A
Khan
Md Rafikul
MR
Islam
Department of Pharmacy, Rajshahi University, Rajshahi 6205, Bangladesh. shahnaj_parvin@ru.ac.bd.
Mst Shahnaj
MS
Parvin
D000975:Antioxidants / Q000032:analysis / Q000494:pharmacology*; D029402:Bignoniaceae / Q000737:chemistry*; D001713:Biphenyl Compounds / Q000378:metabolism; D005419:Flavonoids / Q000032:analysis / Q000494:pharmacology*; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis / Q000494:pharmacology*; D010851:Picrates / Q000378:metabolism; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D013634:Tannins / Q000032:analysis / Q000494:pharmacology
D000975:Antioxidants; D001713:Biphenyl Compounds; D005419:Flavonoids; D005609:Free Radicals; D010636:Phenols; D010851:Picrates; D010936:Plant Extracts; D013634:Tannins; C004931:1,1-diphenyl-2-picrylhydrazyl