Anti-inflammatory activity of endophytic bacterial isolates from Emilia sonchifolia (Linn.) DC

In the traditional medicine system, plants have been utilized as a rich source of anti-microbial, anti-inflammatory, anti-cancer, anti-viral and anti-oxidant compounds. The biological properties of plant-based drugs depend on their interaction with endophytes which persist as an important provider of bioactive secondary metabolites. Bacterial endophytes secrete anti-inflammatory molecules whose activity can be the base for the anti-inflammatory property of the plant.

During the screening of endophytes from Emilia sonchifolia, we isolated six different bacteria whose potential as the sources of anti-inflamamtory compounds have been aimed at in this study.

Anti-inflammatory activity of the ethyl acetate extract of endophytes was studied by both in vitro and in vivo analyses. In vitro study was done using protein denaturation, COX, LOX, iNOS, myeloperoxidase and nitric oxide assays and in vivo analysis was carried out by carrageenan-induced and formalin-induced paw oedema tests. The expression level of anti-inflammatory genes such as COX-2 and NfKb was confirmed by real time PCR.

We confirmed anti-inflammatory activity of the ethyl acetate extract of bacterial endophytes of E sonchifolia by both in vitro and in vivo experiments. Carrageenan- and formalin-induced inflammations in mice were effectively reduced by the administration of the bacterial extract. Among the isolates, strain ES1effectively reduced inflammation. Gene expression studies confirmed reduction in the expression of COX-2 and NfKb genes in the presence of ES1 extract.

The present investigation demonstrated the anti-inflammatory property of the isolated bacterial endophyte ES1 (Bacillus subtilis strain-MG 692780) and thus justifies the possible role of endophytes in contributing anti-inflammatory property to E sonchifolia which is ethno-botanically important as a source of anti-inflammatory drug.