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DDT > DDT 11 -Platinum complexes as anti-cancer agents > Flashcards

DDT 11 -Platinum complexes as anti-cancer agents Flashcards

1
Q

Platinum complexes

A

cisplatin
carboplatin
oxaliplatin

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2
Q

cancer treatments

A

surgery
radiation
chemotherapy

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3
Q

who discovered cisplatin

A

barnett rosenberg

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4
Q

how did Barnett Rosenberg come to discover cisplatin

A

mitotic spindle is similar to electric or magnetic fields patterns in magnets
would electric fields affect cell division

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5
Q

How did Barnett Rosenberg carry out his experiment

A

growth chamber - cells of e,coli in medium w/ NH4Cl, NaCl etc
platinum anode and platinum cathode attach to medium containing bacteria to apply electric field.

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6
Q

What was the result of Barnett Rosenberg experiment

A

bacteria looked like long filaments

cell division was inhibited but not cell growth - RNA and protein synthesis still occurred

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7
Q

What caused the inhibition of cell division when an electric field was applied on bacteria?

A 
Platinum hexachloride
Platinum - inert 
Anode - oxidation of Cl- to Cl2 
CL2 oxidized Pt to Platinum 4+ 
Platinum Hexachloride was formed
Platinum hexachloride in the presence of light and NH4+ 
formed. cis-[Pt(NH3)2(Cl)4 ] + 2HCl
cont...
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8
Q

describe structure of cisplatin

A

platinum core w/ 2 Cl ligands cis to each other and 2 NH2 ligands cis to each other

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9
Q

describe 2 properties that are important for cisplatin

A

neutral charge

sufficiently lipophilic to cross cell membrane

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10
Q

what did Rosenberg realise about Pt compounds

A

inhibited bacterial cell division but promoted cell growth could stop cell division in cancer cells

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11
Q

what did cisplatin work against

A

virally induced tumours and transported tumours

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12
Q

side effects of cisplatin

A

nausea
alopecia
myelosupppression - reduced activity of bone marrow
kidney damage - worst one (nephrotoxicity)

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13
Q

when was the first patient treated w/ cisplatin

A

1971

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14
Q

when were in vivo tests cisplatin performed at the chester beatty institute

A

1968

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15
Q

when was cisplatin FDA approved

A

1978

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16
Q

what cancer type was cisplatin especially beneficial for and why?

A

Testicular cancer

normally killed 80% of people - is now 95% curable

17
Q

types of cancer cisplatin treats

A

in ovarian
bladder
osteogenic sarcoma [bone] cancers

18
Q

what is cisplatin other used with

A

used w/ other anti cancer drugs e.g. vinblastin or bleomycin

19
Q

how is cisplatin administered

A

intravenously every 3-4 weeks in single doses of 50-120 mg per m2 body surface or 15-20 mg per m2 daily for 5 days

20
Q

describe the solution cisplatin is in?

A

injected in 2 litres of NaCl (0.9%) or Glucose (4%) and NaCl(0.18%) solution and is infused for over 6-8 hours
isotonic solution

21
Q

cisplatin - mechanism of action(how did it enter the cancer cell etc.)

A

Neutral - passively diffuse through cell membrane
Can be carried actively thru copper transporter protein
Difference in chloride ion conc. - dramatic drop of Cl- in ion
Cl comes off cisplatin and replaced w/ neutral water via hydrolysis
replaced one negative charged ion (Cl-) with water change charge of active metabolite - +ively charged
attracted to negatively charged sugar phosphate backbone of DNA in nucleus
water comes off are replaced with nitrogen base from DNA and it forms an intranstrand cross-link.
Form chelate structure
Forms kink in DNA - incapable of DNA repair

22
Q

types of DNA Cross links cisplatin induce

A

intrastrand adducts
monoadduct
interstrand adduct
protein DNA cross link

23
Q

transplatin

A

cisplatin with Cl2 trans to each other and same with 2 NH3

24
Q

Cisplatin drawbacks

A

inactive against breast, lung and colon cancer
highly toxic to kidney
cancer cells have developed a resistance to cisplatin

25
Q

why must pt anti cancer drug be cis

A

can activate via hydrolysis
Cl- can be replaced by water and change charge of molecule but in trans configuration the arrangement of the trans configuration only one base can be formed.

26
Q

what does anti-cancer act as when binding with DNA?

A

acts as a chelating agent - over all complex forms a DNA adduct
bidentate binding forms kink in DNA strand and is less likely to undergo repair can undergo cell apoptosis

27
Q

stable platinum complex that isn’t labile = easily broke

A

Pt with Nitrogen or Sulfur

28
Q

why must platinum core have oxidation number of +2 and +4

A

+2 oxidation number gives rise to square planar geometry

+4 gives rise to octahedral shape

29
Q

state two ways in which cells develop resistance to cisplatin

A

increase sulfur containing molecules - Cl gets replaced with Sulfur
Pt - S bond is not labile
Increased DNA repair

30
Q

How does HMG enhance the cytotoxicity in the cell?

A

HMG protein binds to cisplatin modified DNA

enhance cytotoxicity and is harder for DNA repair enzymes to repair DNA

DDT (21 decks)

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