Great Job! Since plicamycin according to your data seemed to be more effective than penicillin, what would be a reason that plicamycin isn’t currently being used more prevalently in todays society?
Hey Nolan, thanks for the feedback. In our lab, Plicamycin actually seemed to be more effective than ampicillin, but further testing using penicillin could have some great potential! Plicamycin was used but discontinued in the early 2000’s because of dose-related bleeding syndromes. This is an issue especially since Plicamycin crosses the blood-brain barrier; Plicamycin tends to stay in brain tissues longer than other body tissues. More research needs to be done on how to prevent lingering concentrations in the brain in order to reduce the risk of bleeding.
What was the purpose of testing different concentrations of plicamycin? And, I apologize if ive understood incorrectly, how come the tests with higher concentrations 5mg weren’t effective but lower concentrations were? Id assume you could never have too much antibacterial drug that it stopped becoming effective against bacteria
Hi Charlotte, thanks for your response. The only concentrations that Plicamycin was effective at – meaning the bacteria was killed- were between 10-5 ug/mL. At lower concentrations, Plicamycin was shown to no longer be effective. We only know this because we had made a 1:2 dilution series which had differing concentrations of Plicamycin. Starting with a stock solution of 1 mg/mL of Plicamycin/DMSO – which more easily translates to 10 ug/mL- we cut this in half, and then that concentration in half, to get 5 ug/mL, 2.5 ug/mL, 1.25 ug/mL, and 0.625 ug/mL. Our absorbances indicated that only concentrations between 10-5 ug/mL had any effect on killing the bacteria.
As Charlotte said, would it be because of some other substance interfering at higher concentrations? Its quite interesting that higher concentrations weren’t effective as lower ones
Hi Cooper, I’m happy to offer some clarity in regard to your question. Starting with a stock solution of 10 ug/mL- we created a dilution series giving us concentrations of 5 ug/mL, 2.5 ug/mL, 1.25 ug/mL, and 0.625 ug/mL. Our absorbances indicated that only concentrations between 10-5 ug/mL had any effect on killing the bacteria. It is unlikely that any other substances interfered, because our stock concentration only used DMSO and Plicamycin, which was then put into wells of Salmonella. DMSO is the solvent we use with Plicamycin to ensure that it is able to enter organisms such as Salmonella.
Hi Rachel, thanks for your response! 10 ug/mL is the max dose that anything can work at in physiological conditions. Anything above this, the body wouldn’t be able to absorb properly. This is why we started with the 10 ug/mL and worked our way down to smaller dilutions.
Great Job! Since plicamycin according to your data seemed to be more effective than penicillin, what would be a reason that plicamycin isn’t currently being used more prevalently in todays society?
Hey Nolan, thanks for the feedback. In our lab, Plicamycin actually seemed to be more effective than ampicillin, but further testing using penicillin could have some great potential! Plicamycin was used but discontinued in the early 2000’s because of dose-related bleeding syndromes. This is an issue especially since Plicamycin crosses the blood-brain barrier; Plicamycin tends to stay in brain tissues longer than other body tissues. More research needs to be done on how to prevent lingering concentrations in the brain in order to reduce the risk of bleeding.
What was the purpose of testing different concentrations of plicamycin? And, I apologize if ive understood incorrectly, how come the tests with higher concentrations 5mg weren’t effective but lower concentrations were? Id assume you could never have too much antibacterial drug that it stopped becoming effective against bacteria
Hi Charlotte, thanks for your response. The only concentrations that Plicamycin was effective at – meaning the bacteria was killed- were between 10-5 ug/mL. At lower concentrations, Plicamycin was shown to no longer be effective. We only know this because we had made a 1:2 dilution series which had differing concentrations of Plicamycin. Starting with a stock solution of 1 mg/mL of Plicamycin/DMSO – which more easily translates to 10 ug/mL- we cut this in half, and then that concentration in half, to get 5 ug/mL, 2.5 ug/mL, 1.25 ug/mL, and 0.625 ug/mL. Our absorbances indicated that only concentrations between 10-5 ug/mL had any effect on killing the bacteria.
As Charlotte said, would it be because of some other substance interfering at higher concentrations? Its quite interesting that higher concentrations weren’t effective as lower ones
Hi Cooper, I’m happy to offer some clarity in regard to your question. Starting with a stock solution of 10 ug/mL- we created a dilution series giving us concentrations of 5 ug/mL, 2.5 ug/mL, 1.25 ug/mL, and 0.625 ug/mL. Our absorbances indicated that only concentrations between 10-5 ug/mL had any effect on killing the bacteria. It is unlikely that any other substances interfered, because our stock concentration only used DMSO and Plicamycin, which was then put into wells of Salmonella. DMSO is the solvent we use with Plicamycin to ensure that it is able to enter organisms such as Salmonella.
What exactly is plicamycin extracted from?
Hello Matei; excellent question! Plicamycin is actually produced by a microorganism called Streptomyces Plicatus.
Are higher concentrations potentially toxic to humans?
Hi Rachel, thanks for your response! 10 ug/mL is the max dose that anything can work at in physiological conditions. Anything above this, the body wouldn’t be able to absorb properly. This is why we started with the 10 ug/mL and worked our way down to smaller dilutions.