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Plant chemistry and interaction in ecology -

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Robyn Williams: I've found out for the first time in my life that's where vanilla comes from. How
come?

Monique Simmonds: Yes, vanilla pods, one of the commercial products made from orchids that has
captured the imagination especially as a flavour, there's nothing really like it.

Robyn Williams: Professor Monique Simmonds at what used to be the Kew Centre for Economic Botany,
now called the Sustainable Users of Plants Group, and they find medicines and useful chemicals,
often by having heard that animals such as chimpanzees use them to make their upset tummies feel
better.

Monique Simmonds: Yes, looking at the use of plants by animals is quite interesting and, as you
say, chimps have been well studied, and we're actually gaining more knowledge about some of the
other herbivores, like cows et cetera, elephants grazing specific plants when they maybe have got
stomach problems. It's interesting to know the relationship between their feeling of being unwell
and the plants that they use to alleviate those symptoms.

Robyn Williams: So you can actually see a pattern? They keep going back to particular ones, is that
right?

Monique Simmonds: They seem to go back to particular species. It's quite well documented in cases
of cows when they'll go back and get plants that have a high concentration of salt and, say,
sugars, but we're getting even more experience of doing it. It doesn't always work out well though
because there are some plants that the animals will go to, and they seem to get a little bit like a
high, like our alcohol, which can cause problem because of course they can get drunk.

Robyn Williams: Cows do that, do they?

Monique Simmonds: There's evidence that cows will go to, say, some fermenting products, also
horses.

Robyn Williams: With such a huge range of plants and indeed chemicals therein, where do you start?
What's been the pattern in Kew looking at these things?

Monique Simmonds: For a long time we were looking at the role of plant chemicals in the
relationships amongst different plants within a family, within the genera, and then at a species
level, to see if they could be used as characters. With the advance of molecular characters, the
DNA characters, plant chemistry has very much come to the fore, and it's got a lot of uses. For
example, if you've got these new phylogenies that are based on the DNA which shows the
relationships with plants and you now superimpose our knowledge about the plant chemistry, that can
highlight plants that we would like to select, say, for a particular use as a drug. Or at times we
can use that knowledge to deselect plants, because if you've got one plant with a known compound
then related plants will most likely have a similar type of chemistry and sometimes you want to
avoid wasting your time identifying something that's already known.

Robyn Williams: An awful lot of these chemicals are often developed in plants to make other animals
and other creatures just go away, they're repellent, they're poisonous or something like that. What
are the other reasons that you get various chemicals turning up, because essentially a plant wants
to do something fairly simple, and you don't want the luxury of another four or five chemical
pathways to have to maintain.

Monique Simmonds: Yes, to produce some of these so-called secondary metabolites is very actually
expensive to the plant to produce, so there must be a reason for doing that, and the fact that they
can't walk away from somewhere means that they really have to defend themselves well. We have an
interest in the role of plant compounds as deterrents for insects, as antifeedants, compounds that
stop the insects from feeding, and they can actually be very host specific. Some actually have
worked the other way, they're used by the insects as kind of sign stimuli that they've got the
right species.

But the other uses of plant compounds is protecting them from UV radiation, and that is a use for
humans because a better understanding of how a plant does it is maybe a way that we can be looking
at some of the plant compounds for potential UV protectants for humans.

Robyn Williams: Yes, ultraviolet light would be damaging, wouldn't it, if it just went straight
into those delicate leaf cells.

Monique Simmonds: It could be very damaging with UV light, and plants at a higher altitude usually
have to protect themselves better and they can do this chemically but they can also do it
physically. There's a lot more to be learned because we thought we knew about the types of
compounds and we put them into different classes, like phenolics, the flavonoids having this role,
but we need to unravel that because there are an awful lot of flavonoids and which ones are
actually better at doing this job.

Robyn Williams: What about HIV? What's the connection with AIDS and ways in which you're
approaching plants to find some sort of remedy?

Monique Simmonds: We were doing some work back in the 1980s in which we identified some plant
compounds that actually affected insects but also affected transmission of viruses and these were
shown to have some potential in the control of HIV because they interfered with cell-to-cell
recognition and therefore the transfer of a virus from one cell to another. So they have a role in
nature and here there's potential use with humans. But what we've been doing in recent years is
actually working with some of the communities, especially in Africa, and looking at some of the
plants that they've been giving to HIV patients. That's quite fascinating because it's a disease
that is relatively new, so how are they selecting those plants?

So we're dealing not with a long history of traditional use, this is something that's evolved in
the last, say, 20, 30, 40 years, and some of the plants when we take them to the laboratory we can
see an effect, not always on the actual virus but on the immune system. So they equip the people
with better ability, you could say, to cope with the virus. But one of the big challenges we face
is that some of these people will be also on anti-viral drugs, and some of the plants can interfere
with the action of those drugs, and so we really need to do more of this work in combination with
those that are giving out the western pharmaceuticals.

Robyn Williams: So clues from animals, clues from people, and I'm reminded also of clues from
evolutionary history because the story of malaria turns out to be a parasite that used to be a
plant, it's got a chloroplast in it. That's being followed up at the University of Melbourne. Have
you come across that story at all?

Monique Simmonds: The control of malaria actually goes back to Kew's history. In our economic
botany collections here we've got some of the early samples of Jesuit's bark from the Cinchona tree
that was used to help develop the production of quinine within the UK. So it's fascinating at Kew
how we have all these crossovers with some of the economic value of plants, especially the samples
that we have in our collections.

Robyn Williams: Quinine, yes, of course, the sort of thing that you get in gin and tonic, from
another sources...it was actually developed, what, way back?

Monique Simmonds: Yes, the quinine samples go back to the 1600s and 1700s. You get it coming into
parts of Europe, and the samples that we have are from the mid 1850s onwards, and for a long time
was the main remedy that could be given for malaria, and now more recently we've got the Artemisian
from the Artemisia. So we've gone back to nature in this case to come up with some potential drugs
against malaria.

Robyn Williams: Isn't it interesting. Do you find yourself returning to some of the collections
when you get clues about other plants and you think, well, hang on, what about those that have been
there for decades, why don't we go back and have a look at them? Does that occur very much?

Monique Simmonds: Over the last few years we have been putting a greater emphasis on what we term
the ethno-botanical information, the traditional use information. We've just done a screen for
plants for the treatment of TB and we've taken some that have got a lot of traditional use, and the
hit rate for those that are used traditionally is much greater than going out and just taking
something that's random. But it doesn't always mean you're going to come up with something that's
safe to use, but there are a lot of those plants out there that definitely justify further
scientific use, especially taking on board the advances that we have now in understanding those
diseases and the better analytical equipment we have to be able to study the chemistry of the
plants.