Potential Assessment of Rumex spp. as a Source of Bioactive Compounds and Biological Activity

Abstract

Secondary metabolites from the shoots and roots of three Rumex species collected from three different habitats were investigated (Rumex dentatus collected from cultivated land, R. pictus collected from the coastal desert and R. vesicarius collected from the inland desert) and tested for antioxidant activity as well as for anti-microbial activity against some human pathogenic bacteria. The present study indicated that the quantitative analysis of shoot and root extracts of three Rumex spp. were found to be rich in tannins and phenolics composition. The aerial parts of the three plants exhibited the highest significant values compared to the root parts. The MeOH extracts of Rumex species showed adequate antioxidant activity, wherein the IC50 values of the MeOH from the cultivated sample was 41.61 and 31.31 mg mL-1, coastal samples were 34.99 and 23.99 mg mL-1, while the sample of inland showed IC50 value of 41.59 and 31.67 mg mL-1, for root and shoot, respectively. Furthermore, using a filter paper disc assay, the MeOH extracts of the three Rumex species showed a substantial anti-microbial inhibitory effect on the growth of 10 pathogenic bacteria. According to sensitivity, the tested organisms could be sequenced as following: E. coli < K. pneumoniae ˂ S. typhi < P. aeruginosa for Gram-negative bacteria and B. subtilis < S. pneumoniae ˂ L. monocytoyenes < S. epidermis < S. aureus < B. cereus for Gram-positive bacteria. In addition, the antibacterial performance of R. dentatus root and R. vesicarius shoot MeOH extract is 100% broad spectrum against Gram-negative bacteria. A shoot of R. dentatus and R. pictus MeOH extract against Gram-positive bacteria is 83.3% broad spectrum. A further study is recommended for more characterization of the major compounds and assesses their efficiency and biosafety.