Antioxidant and antibacterial agents from parmotrema dilatatum (Vainio) hale, knema angustifolia (Roxb.) warb. and persicaria odorata lour

Abstract

In the search of antioxidant and antibacterial agents, the extracts and isolated compounds from lichen Parmotrema dilatatum, Knema angustifolia full name, Persicaria odorata and Mansonia gagei. were examined. Nine compounds were isolated from lichen P. dilatatum including (E)-2,4-dihydroxy-6-methyl-3-(3-oxobut-1-en-1-yl)benzoate (PD.1), hopane-16ß,22-diol (PD.2), methyl orsellinate (PD.3), methyl haemmatomate (PD.4), methyl ß-orcinolcarboxylate (PD.5), 2-hydroxy-4-methoxy-3,6-dimethylbenzoic acid (PD.6), atranol (PD.7), atranorin (PD.8) and lecanorin (PD.9). The dichloromethane and acetone fractions, and atranol (PD.7) gave excellent activities as antioxidants. While in tyrosinase activity the dichloromethane fraction and atranorin (PD.8) showed the highest inhibition. For α-glucosidase inhibition activity, the methanol fraction and methyl haemmatommate (PD.4) revealed the highest activity. The extracts and major constituents from K. angustifolia, P. odorata and M. gagei were determined for their biological activities. Amongst plants K. angustifolia was showed potential activity in DPPH, ABTS, antibacterial, tyrosinase assay and anti α-glucosidase assay. Meanwhile, quercetin isolated from K. angustifolia exhibited prospective antioxidants, anti-tyrosinase and anti-diabetic activities. MG1 and MG3 derivatives of mansonone G showed synergistic effect against S. aureus when combined with streptomycin. Mansonone G and all derivatives showed synergistic effect against S. aureus and S. mutans when combined with tetracycline.