to prepare 100 mg/mL, 50 mg/mL, 25 mg/mL plant extract solutions, how much conc of DMSO need to avoid bacterial interference in the antibacterial susceptibility test.
Concentrations below 5% DMSO in general don't have any antimicrobial activity, but you'll do the solvent-only control as a comparison.
You can also try other solvents like ethanol, again you'd use the solvent-only as a control.
Hello Theerssha Subbramaniam,
You should perform a simple test so as to see how sensitive is your bacteria to DMSO. This test will allow you to use the lowest effective DMSO concentration.
There may be a possibility that your plant extract may not form a homogeneous solution with 5%DMSO, then in such a case, if the extract was originally prepared in a solvent other than DMSO (like say ethanol or methanol), try dissolving the extract in that original solvent first.
Use appropriate controls. Include a negative control with just DMSO at the same concentration used for the extract to account for any potential antimicrobial activity of DMSO itself. Also, include a control with only the solvent used for the extract, without the extract, to ensure that the solvent itself is not affecting the results.
Best,
Solvent only control is lame as it assumes there is no effect of the combination of solvent and extract beyond solubilization. The fallacy is readily observed for low levels of ethanol and water soluble preservatives where the dilute ethanol has no effect but significantly increases the effect of the preservative
That the % of solvent (DMSO) alone has no observed effect is not a technically sufficient control. The dilemma here is that the extract is not soluble without the solvent - making the herbal extract alone unavailable.
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