Hedychium coronarium J.Koenig produced extracellular and intracellular anti-tuberculosis activity with morphological alteration of the tubercle bacillus

Abstract

Hedychium coronarium J.Koenig (Zingiberaceae) is a medium-sized aromatic rhizomatous perennial monocotyledonous plant. The rhizome of H. coronarium is reported in traditional medicine for its use in the treatment of tonsillitis, bronchitis, cough, fever and other respiratory disorders. The present work was carried out to evaluate anti-mycobacterial activity of the ethanolic extract of rhizomes of H. coronarium against respiratory pathogen Mycobacterium tuberculosis (Mtb) with its safety assessment and action on morphology of the bacilli. Anti-mycobacterial activity was assessed using the in-vitro resazurin microtiter plate assay (REMA). The plant extract was further evaluated for its cytotoxicity against human THP-1 macrophages. Ex-vivo intracellular anti-TB activity was also determined using Mtb infected macrophage culture model. Scanning electron microscopy (SEM) was used to examine the morphological changes in Mtb in the presence of plant extract.H. coronarium exhibited promising antimycobacterial activity against drug sensitive Mtb H37Rv and multi drug resistant (MDR) clinical isolates of Mtb with minimum inhibitory concentration (MIC) values ranging from 15.62 to 31.25 µg mL−1. The IC50 (50% inhibitory concentration) of plant extract on THP-1 was found at higher concentration than MIC values against Mtb, indicating that the mammalian cells were not adversely affected at concentrations which are effective against Mtb. The plant extract displayed intracellular killing of bacilli inside the infected macrophages. H. coronarium also produced morphological alteration of the bacilli after 48 and 72 h of treatment. In this study, we conclude that H. coronarium has promising in-vitro and ex-vivo intracellular activity against Mtb and it also displayed activity against rifampicin and isoniazid resistant clinical isolates of Mtb without affecting eukaryotic cells.