so I got a parcel this morning I think I
know what's in it but I'm not sure and
I'm quite excited so let's open it it is
from my friend Peter who is a green
chemist
this is sildenafil citrate compound
which probably most people haven't heard
of but it's the active ingredient of the
pharmaceutical product that is called
viagra
like many pharmaceutical products this
is a salt it's a salt of citric acid
citric acid is quite a common acid you
find them in citrus fruits oranges
lemons so on so here there's seventeen
point nine eight grams so this is more
than enough to make over 300 standard
tablets of Viagra now I'm not going to
open it because after that none of my
male colleagues would want to come into
my office might not want to go into it
myself because viagra is a very potent
drug and it's a potent drug which causes
blood vessels to distend that is to
expand so blood flows around the body
much more easily one of its uses is for
treating so called pulmonary
hypertension so the blood is not flowing
into your lungs properly but if you take
viagra it descends the blood vessels and
so it's easier for the heart to pump the
blood through the blood vessels it also
effects other parts of the body like
many blockbuster drugs when it was
discovered and developed people didn't
realize all the things that could do
they knew that it would distend blood
vessels but it was only when they were
testing it and saw the effect on male
rats that they realized that they were
onto something quite exciting you can
see the compounds white if you've seen
pictures of Viagra tablets they're blue
if you cut one in half and I haven't
done then you would find that the blue
is just a coating on the outside inside
it's just white a mixture of this
compound with some inert filler so that
the tablet is a reasonable size so you
can swallow it easily like many organic
compounds that are complicated it has a
name that is so long so I read it out
because I'll never remember it otherwise
it's one for a tox III six seven-day
hydro one methyl you follow me
seven oXXO three profile 1h Perez low
for 3d that means it's right-handed
pyrimidine five aisle female cell phone
aisle four methyl para scene citrate
when viagra was first made for each ten
gram sample that's about half what I've
got they needed to use thirteen and a
half liters of solvents but then after
Peter done applied the principles of
green chemistry they got this down just
about 60 milliliters of solvents and
that's a huge reduction in the amount of
solvent and they not only reduced the
volume the solvents they used were
environmentally much more friendly so
thanks to my colleague Chris and the one
does a video I now got a model of the
molecule and you can see there's a
sulfur atom here which is yellow the red
ones here and here and here are oxygen
atoms and the blue ones are nitrogen
atoms the others are carbon and the or
hydrogen and you can see the benzene
ring here and another six membered ring
here and it looks quite complicated
chemists have designed this so that it
will fit into a particular place on the
enzyme that they're trying to stop
operating in the body there is an enzyme
called phosphodiester raise which is
known in the trade as pde5 what happens
if pde5 causes the blood vessels to
contract and obviously it is quite
embarrassing if at the wrong moment your
blood vessels suddenly contract when
you'd really like them to relax and so
what viagra does is that it fits into
the active place on the enzyme the so
called active site and blocks it so the
molecule can't work and this is why
chemists have designed this molecule so
the
various nitrogen and atoms and just the
right place so that they can bond on to
the hydrogen's or whatever in the active
sites of the enzyme so it just doesn't
work and your blood vessels stay really
dilated till you're ready for them to go
down