Antioxidant and antibacterial activity of two compounds (forsythiaside and forsythin) isolated from Forsythia suspensa

Forsythia suspensa (Thunb.) Vahl. has been widely used in traditional medicines in Asia to treat gonorrhoea, erysipelas, inflammation, pyrexia, ulcer and other diseases. Recently the investigation has been focused on the antioxidant and antibacterial activity of this plant. However, limited scientifically proven information is available. We isolated two compounds (forsythiaside and forsythin) from this plant. The aims of this investigation, therefore, were to assay antioxidant activity and antibacterial properties of the two main and distinctive compounds isolated and to exploit antioxidants and antibacterial agents from natural compounds. The antioxidant activity was estimated using the 1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity method and the in-vitro antimicrobial activity was evaluated by microtitre plate method. Forsythiaside was found to possess strong antioxidant and antibacterial activity but forsythin was much weaker. Owing to these properties, the study can be further extended to exploit the possible application of forsythiaside as an alternative antioxidant and antibacterial agent of natural origin.