Rapid screening of antioxidant activity, fracture rate and scavenging of free radicals by hairy root of Periwinkle (Catharanthus roseus L. G. Don)

Oxidative stresses caused by free radicals are known to promote many diseases such as inflammation and cancer; therefore, any plant product that can inhibit free radical production can play an important role in preventing diseases. We aimed to compare the fracture rate and the scavenging activity of free radicals, and the antioxidant composition of rolB-transformed hairy root of Catharanthus roseus with those of the plantʼs natural root and leaf. Hairy root of the Madagascar periwinkle (C. roseus) were induced using Agrobacterium rhizogenes strain ATCC 15834 to transfer the rolB gene. PCR analysis was used to identify the geneʼs presence in the transformed hairy root. Folin-Ciocalteu reagent and HPLC were used to determine total phenolics and gallic acid. This study also entailed rapid screening of antioxidant by dot-blot DPPH staining on thin-layer chromatography (TLC), radicals fracture rate, free radical scavenging by 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, and nitric oxide-scavenging activities by Griess reagent. Our results showed that phenolic and gallic acid content in the ethanol extract of hairy root was significantly higher (p ≤ 0.05) than that naturally found in the root and leaf of C. roseus. The hairy root extract had the highest dot-blot staining and fracture rate of radicals and the lowest IC50 for inhibition of DPPH• and •NO. The transgenic hairy root of C. roseus showed high number of scavenging radicals, whereas the most active ethanol extract of hairy root registered by the highest level of gallic acid and total phenolic content. The transformed hairy roots can be considered as a rich natural source of antioxidants.