Page 426 - Carrahers_Polymer_Chemistry,_Eighth_Edition

Organometallic and Inorganic–Organic Polymers 389

compounds generally degrade to nontoxic inorganic compounds so that they are “environmen-
tally friendly.” The second reason concerns the commercial availability of a wide variety of
organotin compounds that are suitable as monomers. Third, because of the biological activity of
organotin compounds they were found to inhibit the growth of desirable species, in particular,
in aquatic surroundings. This brought about federal laws that prohibited the use of leachable,
monomeric-organotin compounds in a variety of coatings and protective applications. The result
was a move to polymeric materials that did not suffer the same leachability and which were
allowed by law.
Much of the recent activity with organotin compounds, including polymers, involves their use
to inhibit a wide variety of microorganisms at low concentrations. These microorganisms include a
variety of cancers, bacteria, yeasts, and viruses. Carraher, Roner, Barot, and coworkers have found
that some simple organotin polyethers based on hydroxyl-terminated poly(ethylene glycols) inhibit
a wide variety of cancers, including ones associated with bone, lung, prostate, breast, and colon
cancers.

H C O
3
CH 3
Sn O
n x (11.20)
C
H 3
CH
3
Two measures are typically employed to measure the ability of cancer cells to grow. The fi rst
is the concentration needed to inhibit 50% growth of the cell line, GI . Some of these polymers
50
have GI values well below those of cisplatin, the most widely used anticancer drug. The second
50
measure is the chemotherapeutic index, CI, which is the concentration of the compound that inhibits
the growth of the healthy or normal cell by 50% divided by the concentration of the compound that
inhibits the growth of the cancer or tumor cell by 50%. Larger values are desired since they indicate
that a larger concentration is required to inhibit the healthy cells in comparison to the cancer cells,
or, stated in another way, larger values indicate some preference for inhibiting the cancer cells in
preference to the normal cells. Some of these polymers have CI values in the hundreds, allowing
healthy cells to reproduce at concentrations where cancer cell lines are inhibited. Of additional
interest is that some of these organotin polymers are water soluble, allowing for medical applica-
tions utilizing the material in simple pills.
A wide variety of organotin compounds developed by Carraher, Sabir, Roner, and others on
the basis of known antiviral drugs such as acyclovir and known-antibacterial agents such as cipro-
fl oxacin, norfloxacin, cephalexin (11.21), and ampicillin, inhibit a wide variety of viruses, including

the ones responsible for many of the common colds, chicken pox, small pox, shingles, and herpes
simplex.

R
NH

O

HN S
(11.21)

N
CH
O 3
R
R 1
Sn
O
O
R 1

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