Story Of Cis-platin

History of the great invention in science

"God didn’t make anything so complicated that it can’t be worked out"

Barnet t Rosen berg(19

Mitosis cell division

Magnetic and Electric Field Lines

Idea ! • To study the effect of electric fields on Cell Division (like Mitosis) • Started with Escherichia coli bacterial cells

Experimental Setup • An audio oscillator was used to supply sinusoidal voltages of 50 to 100,000 cycles/second (c/s). These signals were amplified by a conventional audio power amplifier and then sent to a pair of platinum electrodes in the chamber

In The First Experiment… • The electric field (1,000 c/s), After 1 hour, cell growth was slowing down • After 2 hours, the bacterial population was almost completely washed out, The voltage was turned off • After 8 more hours, the population density of the bacteria returned to its previous value

Result ?

When Freq. was 500 - 6,000 c/s • Bacterial cells stopped dividing and started to elongate and forming long filaments • After the voltage was removed, the cells continued to increase in length, but after 2 hours had elapsed, cell division started to occur again.

Effect of Frequency applied • At 500 c/s, filamentous growth was at a maximum • At 6,000 c/s, no filaments could be seen • For 6,000 to 100,000 c/s no filament could be seen even after 24 hr

Role of atmosphere • Filamentous growth occurred at the frequencies mentioned above only when oxygen was present • If nitrogen or helium, were bubbled through the cell, no effect was observed

Control Experiments • The filamentous growth can be caused by ‫ ٭‬Dyes such as methylene blue and penicillin ‫ ٭‬Transfer to an unaccustomed medium ‫ ٭‬Osmotic pressure changes ‫ ٭‬Near ultraviolet irradiation ‫ ٭‬Magnesium deficiency or excess ‫ ٭‬Temperature ‫ ٭‬pH

The application of an electric field to the bacterial medium might have led to an electrolysis reaction and that the chemical products of this reaction might have affected bacterial cell division

ELECTRODE and CULTURE MEDIUM

BACTERIA and CULTURE MEDIUM

• The application of the electric current was not itself responsible for the observed effects on bacterial growth • Rather that the electric current led to the formation of a new chemical species that affected bacterial elongation • Oxygen had to be present for bacterial elongation to occur

Is an Oxidizing agent? • It gives positive result to the potassium iodide-starch test M2+ + 2 II- + I2 M2+ + 3 I-

M0 + I 2 I3 M0 + I3-

redox reaction acid-base reaction net reaction

• Ordinary medium gave no reaction with potassium iodide and starch

Intensity of the blue color corresponded to the frequency of the applied voltage The frequency was 500 c/s, the blue color was most intense The frequency was 6,000 c/s, the blue color was not detectable

Who is the mystery oxidizing agent? • Several possible oxidizing agents could be created from the medium during electrolysis hypochlorite ion (ClO-) chlorite ion (ClO2-) chlorate ion (ClO3-) perchlorate ion (ClO4-) hydrogen peroxide (H2O2) hydroxylamine (NH2OH) persulfate ion (S2O82-)

Negative results-(Starch iodide Test) • • • • • •

Phosphate ion (PO43-) Sulfate ion (SO42-) Phosphate ion + glucose Phosphate ion + sulfate ion + glucose Sodium sulfate (Na2SO4) Sodium carbonate (Na2CO3)

Positive results-(Starch iodide Test) • • • •

Ammonium sulfate ((NH4)2SO4) Ammonium carbonate ((NH4)2CO3) Ammonium chloride (NH4Cl) Sodium chloride (NaCl) gave a faint positive response

Clue! Platinum electrodes could be attacked by an acidified chloride solution during electrolysis, generating PtCl62-

Later Results… • (NH4)2PtCl6 was shown positive potassium iodide-starch test(>100 ppm) • A later account suggests that (NH4)2PtCl6 at first caused cell death then later, after standing on a laboratory shelf for a few weeks, produced a small number of filaments

Cobalt (Co) Iridium (Ir) Nickel (Ni) Osmium (Os) Palladium (Pd) Rhodium (Rh) Ruthenium (Ru) Platinum-containing compounds

(NH4)2PtIVCl6+ uv light

PtIV(NH3)2Cl4

Action of Cisplatin Cisplatin coordinates to DNA and that this coordination complex not only inhibits replication and transcription of DNA, but also leads to programmed cell death (called apoptosis)

Cisplatin in cell level

Binding site in Base Pairs…

Geometrical Isomer

• In vitro studies on both prokaryotic and eukaryotic cells revealed that DNA adducts of both cisplatin and trans-DDP blocked the action of DNA polymerase • In vivo studies showed that cisplatin and trans-DDP inhibited replication equally well • DNA replication is not the only factor important for the clinical activity of cisplatin

The cytotoxic activity of cisplatin may arise from the cell’s inability to repair DNA damage caused by cisplatin.

• The cell detects DNA damage by the action of damage recognition proteins • HMG-domain proteins bind cisplatin–DNA adducts in vitro • In vivo assays on yeast shown that HMGdomain proteins are important for the activity of cisplatin: • These effects may also be in operation in mammalian cells

Role of HMG domain proteins 1. HMG domain containing transcription factors bind preferentially to the cisplatin–DNA adducts, they could wreak havoc with the transcriptional machinery 2. When HMG domain proteins bind to the cisplatin–DNA adducts, the adducts would not be recognized by the repair machinery

DNA-Cisplatin-HMG adduct

2G Drugs

3G drugs

Drug Resistance • Acquired resistance – Drug is initially beneficial but becomes ineffective over time • Intrinsic resistance – Drug is ineffective from the outset

Resistance Mechanism • Decreased Intracellular Accumulation • Sulfur-Containing Macromolecules • Increased DNA Repair

Side Effects • • • • •

Thrombocytopenia Leukopenia Anemia Nephrotoxicity Ototoxicity

Cisplatin was approved as an anticancer drug in 1978 by the Food and Drug Administration

$250 million in royalty !!!

Synthetic path way of Cisplatin

"In the fields of observation, chance favors only the mind that is prepared " - Louis Pasteur

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