Background: Bacterial multi-drug resistance is one of the serious issues in the worldwide.
The majority of drug resistance developed by bacteria is derived from the formation of biofilm
and the production of several virulence factors.
Objective: To combat the emerging drug resistance nature of bacteria, we have used some
medicinal plants such as Stevia rebaudiana, Cymbopogon flexuosus, Matricaria chamomilla,
Ocimum sanctum, Phyllanthus amarus and Thymus vulgaris for the extraction of active
molecules that can inhibit the biofilm formation and bacterial growth.
Materials & Methods: Each extracted compounds were checked for anti-bacterial, antibiofilm, and anti-virulence activities against Gram-positive and Gram-negative pathogenic
bacteria. Soxhlet method of extraction was used for obtaining crude extracts. Agar disc
diffusion and 96-wells microplate spectroscopic reading were used to detect the antibacterial
and antibiofilm properties of extracts. Crystal violet staining was used for the detection of
biofilm cells. GC-MS analysis was carried out to identify the chemical constituents present in
Results: At a concentration of 25 mg mL-1
, the highest antibacterial activities were obtained in
M. chamomilla acetone extract (CHAAC) against E. coli (17.66±1.15 mm), S. Typhimurium
(13.66±1.52 mm) and S. sonnei (14±1.73 mm). M. chamomilla chloroform extracted (CHACE)
showed effective against S. aureus (30±2 mm) and P. aeruginosa (13.66±1.52 mm). The
minimum inhibitory concentration of crude extracts derived from M. chamomilla was 0.
against S. aureus. Furthermore, the oil extract from C. flexuosus (LEGO)
exhibited significant antibacterial activity against S. aureus (at 0.781 µg mL-1
). The potent
anti-biofilm activity was observed in G. superba (KALO) against E. coli (78.6%) and S.
typhimurium (79.1%), and V. negundo (VNO) against S. Typhimurium (87.3%). Furthermore, the GC-MS analysis showed the presence of active chemical constituents in the extracts which
might have been effective anti-bacterial, anti-biofilm, and anti-virulence properties.
Conclusion: The extracts from the medicinal plant showed antibiofilm, anti-virulence
(attenuation of pyocyanin, LasA, vilacein, and swarming motility) activity towards the
pathogenic bacteria. GC-MS analysis confirms the presence of an active component in the
extracts. Future study is required to purify the bioactive molecules and elucidate the molecular
mechanism of antibiofilm and anti-virulence properties.