Characterization of antioxidant and antibacterial compounds from aerial parts of Haplophyllum tuberculatum

Abstract

The aerial parts of Haplophyllum tuberculatum (H. tuberculatum) have traditionally been used by local communities to treat fever, gastrointestinal disorders, worms, malaria and fractures, however, the responsible ingredients of the selected medicinal plant have not been identified. In the present study, antibacterial and antioxidant ingredients were isolated and characterized from the plant parts of locally grown H. tuberculatum, and their biological activity was evaluated. The powder aerial parts were extracted with methanol and the extract was successively fractionated with different polarities of solvents. All polarities of extracts (hexane, chloroform, ethyl acetate, butanol, methanol and water) were used to determine their antibacterial and antioxidant activity by established in-vitro method. The disk diffusion and free radical scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) methods were used to evaluate antibacterial and antioxidant activities of the prepared extracts and pure isolated compounds at different concentrations against three strains of Gram-positive and three Gram-negative bacteria. The antibacterial activity results showed that all prepared fractions and isolated pure compounds of the plant species gave significant activity against all Gram (+ and –) bacterial strains with the range of inhibition 0–20 mm. The antioxidant activity of the prepared extracts at all concentrations also showed substantial activity. Based on the highest activity, ethyl acetate and chloroform extracts were selected for the separation and isolation of antioxidant and antibacterial compounds by thin layer chromatography (TLC), column chromatography (CC), and preparative thin layer chromatography (PTLIC). The structure of the isolated antioxidant and antibacterial compounds from the ethyl acetate and chloroform extracts were determined on the basis of nuclear magnetic resonance (NMR) and mass spectra. The isolated pure compounds and active extracts could be used as a medicine for various infectious related diseases.