The beach spider lily, Hymenocallis littoralis, has medicinal benefits. It has anti-viral properties and is useful in tumour or cancer cases. It also inhibits biofilm formation – important in overcoming pathogens. Biofilms make cells impermeable to antimicrobials and can cause antibiotic resistance. However, we lack studies on the active compounds that inhibit biofilm formation.
Last fortnight, Kailas D. Sonawane and others from the Shivaji University, Kolhapur reported investigating the antimicrobial, antioxidant and antibiofilm mechanisms of phytochemicals from H. littoralis leaf extracts. They dried and powdered healthy green H. littoralis leaves, collected from their campus, and extracted phytochemicals from the powder using methanol. Then, they tested the extract and found that it had good antioxidant properties, probably due to the phenols and flavonoids present. These phytochemicals help scavenging reactive oxygen species, harmful to cells, and exert wound healing properties.
Using Liquid Chromatography and Mass Spectroscopy, the team identified most of the phytochemicals with antimicrobial activity. They found that the extract had antimicrobial activity against five pathogenic microorganisms that produce biofilms: Staphylococcus aureus and Candida albicans, Bacillus subtili, Salmonella typhimurium and Proteus vulgaris.
The extract showed good binding behaviour at the active site residues of adhesin proteins – Sortase A and Als3 – suggesting its ability to inhibit the adhesion process in biofilm formation.
The researchers tested the extract’s antimicrobial action against pathogenic microorganisms using agar well diffusion. And compared the action of Ampicillin and Amphotericin B, an antibiotic and an antifungal, using concentrations similar to those of the phytochemicals. The researchers used the diameter of the zone of inhibition to measure antimicrobial activity.
They found that the maximum zone of inhibition was against C. albicans and S. aureus. From the growth curve, and the minimum concentration required to inhibit biofilm formation, they found that the extract worked against both S. aureus and C. albicans. Just 45μg/mL was enough for S. aureus while C. albicans needed 70 μg/mL.
“Thus, the H. littoralis extract can be used against various biofilm producing drug resistant microorganisms. However, before the extract can be used as antimicrobial therapy, more studies are needed,” says Kailas Sonawane, Shivaji University, Kolhapur.
Ethnopharmacol., 222: 121-132