Chemical preservatives have been used in the food industry for many years.
However, with increased health concerns, consumers prefer additive-free products
or food preservatives based on natural products. This study evaluated
antimicrobial activities of extracts from Emilia sonchifolia L. (Common name: lilac
tassel flower), Tridax procumbens L. (Common name: tridax daisy) and Vernonia
cinerea L. (Common name: Sahadevi), belonging to the Asteracea family, to explore
their potential for use against general food spoilage and human pathogens so
that new food preservatives may be developed. Three methanol extracts of
these plants were tested in vitro against 20 bacterial species, 3 yeast species, and
12 filamentous fungi by the agar diffusion and broth dilution methods. The V.
cinerea extract was found to be most effective against all of the tested organisms
and the methanol fraction showed the most significant (p < 0.05) antimicrobial
activity among all the soluble fractions tested. The minimum inhibitory
concentrations (MICs) of extracts determined by the broth dilution method ranged
from 1.56 to 100.00mg/mL. The MIC of methanol fraction was the lowest in
comparison to the other four extracts. The study findings indicate that bioactive
natural products from these plants may be isolated for further testing as leads in
the development of new pharmaceuticals in food preservation as well as natural
plant-based medicine.