Pavithra GM, Abhishiktha S. Naik, Saba Siddiqua, Vinayaka KS, Prashith Kekuda T R, Mukunda S
The present study was carried out to determine antioxidant and antibacterial activity of solvent extracts of flowers of Calycopteris floribunda (Roxb.) Poiret (Combretaceae), Humboldtia brunonis Wall (Caesalpinaceae) and Kydia calycina Roxb (Malvaceae). The powdered flowers were extracted successively with petroleum ether, chloroform and methanol based on increased solvent polarity. Antibacterial activity of solvent extracts was performed against two Gram positive and two Gram negative bacteria by Agar well diffusion method. Antioxidant efficacy of solvent extracts was determined by DPPH free radical scavenging assay and Ferric reducing assay. Total phenolic and flavonoid contents were estimated by Folin-Ciocalteau reagent and Aluminium chloride colorimetric estimation method respectively. Maximum extract yield was obtained with methanol followed by chloroform and petroleum ether. Methanol extract of C. floribunda exhibited stronger antibacterial activity followed by H. brunonis and K. calycina. The flower extracts have shown dose dependent scavenging of DPPH free radicals. Scavenging activity was recorded highest in H. brunonis followed by C. floribunda and K. calycina. Methanol extracts have shown remarkable scavenging potential followed by chloroform and petroleum ether extracts. In ferric reducing assay also, methanol extracts exhibited stronger reducing power than other solvent extracts. Methanol extract of C. floribunda showed reducing potential greater than that of ascorbic acid. Total phenolic and flavonoid contents were also high in methanol extracts of flowers and these contents were high in H. brunonis. A marked antibacterial and antioxidant activity of flower extracts was observed in this study. A positive correlation was observed between antioxidant activity and total phenolic and flavonoid contents of solvent extracts. However, such correlation was not observed in antibacterial activity. The presence of secondary metabolites such as flavonoids and phenolic compounds might be related to the antibacterial and antioxidant activity of flower extracts. These flowers can be used to prevent oxidative damage and to treat infectious diseases. Further, isolation of active principles and determination of their efficacies are under progress.
