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Plant of the Month 2018

Flower_SCI Summer Reception 2017

In recent months Plant of the Month has taken inspiration from SCI’s SCIence Garden, which was launched in July 2017. Dr Alison Foster and committee members of SCI’s Horticulture Group played an integral role in bringing the Garden to life, with a diverse array of plants representing SCI’s technical and regional groups. The Garden also showcases the connections between all areas of chemistry related science and highlights the intrinsic role played by natural resources and the environment in industry.

Archive issues of the Horticulture Group newsletter, including Plant of the Month up to March 2017, can be found here.

August: Catharanthus roseus, Madagascar periwinkle

August in the SCIence Garden

Madagascar periwinkleGrowing well this summer in the heat on the Leverhulme Terrace is the pink flowered Catharanthus roseus, the Madagascar periwinkle. It actually makes for a great bedding plant in hotter, drier climates.

As the name suggests, it originates from Madagascar, although it is now widespread across the tropics and sub-tropics and is even considered an invasive weed in some areas. The leaves of the plant were traditionally made into a tea to treat diabetes. In the 1950s a physician in Jamaica sent a sample to his brother, a research scientist in Canada, to investigate further. No anti-diabetic activity was found but it was observed that the test animals suffered from depleted white blood cell levels. This suggested that the plant could have potential as an anti-cancer agent and so the search began for the active constituent(s). The two main chemicals responsible for the activity were identified as vincristine and vinblastine and these two drugs have since been rigorously tested and proven to be very effective.

Vinblastinevinblastine Vincristinevincristine

Vincristine was approved by the FDA in 1963. Both molecules work by inhibiting the assembly of microtubule structures which arrests the cell cycle in the metaphase. These drugs are important components of many chemotherapy regimens. Vincristine is especially important for the treatment of childhood leukemia. The chemical structures are very complicated and, although total synthesis has been achieved in the laboratory, it is not a commercially viable process.

Madagascar periwinkleEven though the plants only contain very small quantities of the chemicals, they are farmed commercially in places such as Texas, USA in order to extract the chemicals. Vincristine makes up 0.0003% of the dry weight of the plant with vinblastine more abundant at 0.01%. Fortunately, vinblastine can be transformed into vincristine by chemical transformation.

However, due to the efficacy of these drugs and although they have been approved and in use for over 50 years, new ways to produce these drugs are still being investigated.

The biosynthetic machinery the plant uses to produce these molecules is being actively studied by researchers based at the John Innes Centre in Norwich, UK. Recently, Sarah O’Connor and co-workers have elucidated the previously missing steps of vinblastine biosynthesis1. Future aims include reconstituting the entire biosynthetic pathway in a heterologous platform to enable a more efficient production of the drug.

1Missing enzymes in the biosynthesis of the anticancer drug vinblastine in Madagascar periwinkle
BY Lorenzo Caputi, Jakob Franke, Scott C. Farrow, Khoa Chung, Richard M. E. Payne, Trinh-Don Nguyen, Thu-Thuy T. Dang, Ines Soares Teto Carqueueiro, Konstantinos Koudoounas, Thomas Duge De Bernonville, Belinda Ameyaw, D. Marc Jones, Ivo Jose Curcino Vieira, Vincent Courdavault, Sarah E. O’Connor
PUBLISHED ONLINE 03 MAY 2018. DOI: 10.1126/science.aat4100

July: Founders and early members of SCI

July in the SCIence Garden

Dahlia 'David Howard'July is the month of the SCI AGM, so it is a good time to celebrate the founders and early members of the Society. The garden contains plants to help us do this, in addition to those that represent the Technical and Regional Interest Groups.

Left: Dahlia ‘David Howard’

First among these plants is Roscoea purpurea. The genus was named for William Roscoe (1753-1831), a Liverpudlian lawyer who opposed the slave trade, promoted the arts, was a founder of the Liverpool Botanic Garden, and most importantly for SCI was the grandfather of Sir Henry Roscoe, chemist, who was the founding President of SCI. The Roscoea can be found growing under the trees in the long narrow bed along the side of the raised terrace in the garden of No 15.

Bringing the colour orange to the garden through the late summer is Dahlia ‘David Howard’. Growing in the large bed of No. 15 this plant celebrates another early President of SCI.

David Howard, the chemist, was president of SCI from 1886 to 1887. He was a chemical manufacturer in East London. He was a chemical manufacturer, eventually running the family business, Howard and Sons, which manufactured fine chemicals such as borax, citric acid and ether. They also extracted and purified plant products such as cocaine, but during the nineteenth century their most profitable product was the anti-malarial drug, quinine.

Quinine moleculequinine

 

 

 

John Eliot Howard, David’s uncle, conducted much of the early work on the extraction of the cinchona alkaloids, including quinine, from the bark of the Cinchona trees. This is an interest that he passed on to his nephew, David.

One of the products, Quinisan, (quinine pills) was marketed to “stop colds and ‘flu in 24 hours”.

There are no Cinchona trees growing in the SCIence garden, as the climate is just not tropical enough but there are plants of Artemisia annua, another plant that is the source of anti-malarial medication.

As an aside, the David Howard that the Dahlia was actually named for is a nurseryman from Suffolk who runs one of the largest UK wholesale nurseries, Howard Nurseries Ltd. When growing Dahlias from seed in the 1950’s when still a teenager he noticed this particular seedling, an offspring from Dahlia ‘Bishop of Llandaff. It was introduced to the trade in 1960 and has since won an RHS Award of Garden Merit.

We hope you enjoy it growing in the SCIence Garden.

June: Tanacetum coccineum ‘James Kelway’

June in the SCIence Garden

Tanacetum coccineum ‘James Kelway’Flowering now in the SCIence garden are the plants of Tanacetum coccineum ‘James Kelway’. This red-flowered ornamental daisy represents the Agrisciences group, since it is a source of the insecticide pyrethrum. Although it is not the one most commonly used commercially, it is the more ornamentally attractive for the garden!

Pyrethrum plants are believed to have been used as insecticides since 1000BC. Tanacetum cinerariifolium is endemic to the East coast of the Adriatic Sea, from Italy to northern Albania through Croatia, Bosnia and Herzegovina and Montenegro. Tanzania produces the majority of the world’s commercial supply of pyrethrum, producing almost 7,000 tonnes in 2015.

Pyrethrum, the insecticide, is an extract of the pyrethrum plant, most commonly Tanacetum cinerariifolium (synonyms are Chrysanthemum cinerariifolium, Pyrethrum cinerariifolium). The chemicals in pyrethrum that have the insecticidal activity are the pyrethrins. There are numerous different molecules within this group, which can be grouped depending on whether the structure contains 3 or 5 oxygen atoms.

Pyrethrin IPyrethrin I

 

Pyrethrin IIPyrethrin II

 

The key step in the biosynthesis of the pyrethrins involves the dimerization of two molecules of dimethylallyl pyrophosphate via the action of the enzyme chrysanthemyl diphosphate synthase, to form the key cyclopropane ring. Pyrethrin II is derived from pyrethrin I via oxidation of a methyl group to the methyl ester. Pyrethrins degrade rapidly in the environment.

Pyrethroids are a group of synthetic insecticides first developed by scientists at Rothamsted Research in the 1960’s and 1970’s. They are typically more persistent in the environment than the naturally occurring compounds, which are degraded by exposure to light. Permethrin is the most widely used pyrethroid. In addition to being an effective insecticide for use in agriculture, it is on the World Health Organisation’s List of Essential Medicines as it is used to treat lice and scabies. It is also used to spray onto mosquito nets and clothing to kill insects landing on them.

PermethrinPermethrin

 

May: Dye Stuffs

May in the SCIence Garden

Plant of the Month - May 2018Whilst across the countryside the fields will be turning yellow this month, as the oil seed rape (Brassica napus) comes into flower, in the SCIence garden there is also a small sea of yellow beneath the Eucommia ulmoides tree.

These particular yellow flowers in the SCIence garden belong to the plants of Isatis tinctoria, a member of the cabbage family, as is the oil seed rape. But this plant is not being grown at SCI for the flowers - it is being grown as it is the source of a purple dye. A common name for this plant is woad, and woad is a source for the production of indigo.

Plant of the Month - May 2018Visitors to the SCIence garden will have to wait until a little later in the year (the exact timing being weather dependent) to see the flowers of Indigofera heterantha, an ornamental shrub closely related to the traditional source of indigo. This plant produces pretty racemes of pink flowers and can be found growing against the wall of the mews property at the back of the SCIence garden.

Indigo itself is not present in the woad plants, nor is it present in the plant it lends it name to, Indigofera. Indigo is really an artefact of specialised metabolites present in these plants.

Plant of the Month - May 2018The precursor to indigo, indoxyl, is found as a derivative and this is what differs between the alternative plant sources. In woad, indoxyl is found as an ester - isatan B (indoxyl-5-ketogluconate) whereas in Indigofera species it is found as indicant, a glucoside (indoxyl-β-D-glucoside). When the carbohydrate portions are cleaved from the indoxyl group in the presence of oxygen in the air, two indoxyl moieties combine to form indigo.

When the leaves of the woad plant are damaged, enzymes released take care of the cleavage of the ketogluconate from the indoxyl.

Plant of the Month - May 2018

Until the dawn of the modern chemical industry, all dyes and pigments were derived from natural sources - vegetable, animal or mineral. Today although many of these products are deemed to be “synthetic”, in fact the starting materials for the production of synthetic dyes, the by-products of the petrochemicals industry, are also ultimately derived from plants - just those that were growing millions of years ago and are now extracted as oil and gas.

Plant of the Month - May 2018The very first synthetic dye was mauveine, also known as aniline purple or Perkin’s mauve. Discovered accidentally by William Perkin in 1856, whilst he was attempting to synthesise quinine, it is amongst the first dyes to have been mass produced. It took almost another 140 years for the exact structure of the dye molecule to be determined.

Picture left: Mauveine a

Also growing in the SCIence is Erysimum ‘Bowles Mauve’, planted to celebrate this link to the beginnings of the synthetic dye industry. This perennial wallflower will also be flowering during May.

April: 2019 - Year of the periodic table

April in the SCIence Garden

Periodic TableIn December 2017, the United Nations announced that 2019 would be the International Year of the Periodic Table of Chemical Elements (IYPT).

This coincides with the 150th anniversary of the discovery of the Periodic System by Dmitry Mendeleev and also the centenary of IUPAC (International Union for Pure and Applied Chemistry).

Celebrating the IYPT will raise global awareness of how chemistry promotes sustainable development and provides solutions to global challenges in energy, education, agriculture and health.

https://iupac.org/united-nations-proclaims-international-year-periodic-table-chemical-elements/

Ceratostigma_plumbaginoides_'Hardy_Blue-Flowered_Leadwart'_(Plumbagnaceae)_flowerOnce again, the SCIence Garden will be an excellent tool to enable a wide audience to understand the power of chemistry. There are already some plants growing here, for the purpose of representing a particular element in the Periodic Table.
Recently planted examples include: Lonicera henryi ‘Copper Beauty’, Ceratostigma plumbaginoides, Hedera helix ‘Silver King’. There are many more that could be planted. Read more about possible examples here here.

Plant right: Ceratostigma plumbaginoides, Hardy Blue-Flowered Leadwart (Plumbagnaceae) flower

March: Pulmonaria cultivars

March in the SCIence Garden

Prunus mume Beni-chidoriIn flower now in the SCIence Garden at Belgrave Square are three different coloured Pulmonaria cultivars, along with Narcissus ‘Carlton’, Euphorbia amygdaloides, a Prunus mume ‘Beni-chidori’ and the last few Eranthis hyemalis and Galanthus woronowii.

Plant left: Prunus mume Beni-chidori

Euphorbia amygdaloides and Narcissus CarltonThe Pulmonaria were planted in the SCIence garden, partly because they had previously been featured as a Horticulture Group plant of the month (April 2016) but partly due to their association with the Doctrine of Signatures, one of the first “theories” about medicinal plants devised by mankind. Though we now know that the plants associated with this theory, are only by chance medicinal and that the Pulmonaria definitely isn’t, it is worth reminding ourselves of the power of plants.

Plant right: Euphorbia amygdaloides and Narcissus Carlton

Pulmonaria Sissinghurst WhiteThe complex array of specialised metabolites produced by plants are not there directly for our benefit, but enable the plant to fend off attackers of all sorts that would shorten its life and prevent it from reproducing. That these molecules have biological activity against diseases of humans, should not really be a surprise.

Plant left: Pulmonaria Sissinghurst White

February: Chemical phobia?

Plant of the month Feb 2018_Gardening without chemicalsWherever I am in the world, signs and information panels seem to jump out at me alerting me to “chemical-free” products. Inevitably, this invokes a long rant about how nothing can be chemical free as everything around us is made up of chemicals!

Last year, on a trade stand at a show, I spotted a poster encouraging people to “Garden without Chemicals”. The poster was sitting on top of a rack of pheromone traps – for codling moth and plum fruit moth. Should I report them to Trading Standards? If they are asking people to garden without chemicals, then surely they are selling them an evacuated packet?

The sex attractant of the codling moth has been characterised as trans-8, trans-10-dodecadien-1-ol and that of the plum moth as cis-8-dodecenylacetate.

Plant of the month Feb 2018_image 1codling moth sex attractant



Plant of the month Feb 2018_image 2plum moth sex attractant



More recently, I spotted a restaurant claiming to use only “chemical free soy sauce”. I was dragged onwards before I could get a photo of the sign, but it did lead me to investigate what they meant. One of the leading brands of soy sauce, proudly claims to be naturally brewed rather than chemically made. What, I ask myself, so they think brewing and fermentation involves, if not chemicals? I’m not disputing that there are different methods to make the product that claim to be soy sauce, but I am strongly advocating that a better choice of words is found to distinguish the two processes, which are both chemical processes.

My most recent and perhaps most upsetting example was seen in a botanic garden. To see such a blatant example of chemophobia in a scientific institution I have to admit was infuriating. The offending interpretation was about Eucalyptus oil.

Plant of the month Feb 2018_Why nature is better for your familyMuch of the interpretation was interesting and informative but then the anti-chemical propaganda started. The public were assured that because eucalyptus oil is natural it is an ideal way to create a healthy home. Of course, this oil has many uses around the home, but would you drink it? What does safe mean? Just because something is natural, this does not mean it is better or safer than something that has been synthesised in a laboratory or factory. It could be exactly the same!

Some responses by members of the public who have used a particular brand of eucalyptus oil showed that they had been misled by the advertising. One person was quoted as saying “I no longer rely on chemicals inside or outside my home”. What then do they do? I assume they are no longer breathing. Air, being made of chemicals (such as oxygen, nitrogen and so on), must surely have been deemed too toxic to be safe.

What is Eucalyptus oil made of? Chemicals! Specifically, the majority of the content is cineole (also known as eucalyptol).

Plant of the month Feb 2018_image 3

Two different views of the chemical structure of cineole





As a trained chemist, who does a lot of public speaking about the chemistry of the world around us, I work to counter this chemophobic attitude as much as I can. I shall certainly be giving some feedback to the botanic garden I visited.

The SCIence Garden at 14/15 Belgrave Square is an excellent way to engage with people who may be “chemophobic”. In the garden they are confronted by plants - the “natural” world and learn about the chemistry of these plants and how they are linked to the chemical industry across the world. A great way to change opinions and break down barriers.

I’d love to hear of other examples of misleading signs and advertising. Perhaps together we can make a difference to the public attitude to “chemicals”.

January: Galanthus woronowii Snowdrop, Amaryllidaceae

January in the SCIence Garden

Galanthus woronowii, Snowdrop, AmaryllidaceaeThe weather has been so topsy-turvy this winter – with temperatures fluctuating wildly it is hard to know when the first snowdrops will flower in the SCIence garden. What we do know is that they are keenly anticipated!

The snowdrop species that has been planted in the SCIence garden is Galanthus woronowii. Rather than the narrow glaucous leaves of the common snowdrop (Galanthus nivalis), this Caucasian species has bright shiny green, wide leaves underneath the nodding white flowers. These shiny green leaves emerge with one leaf tightly clasped around the other. This is described by botanists as supervolute vernation. Which kind of vernation a snowdrop exhibits assists in the identification of the particular kind. There are two other main kinds of vernation  applicable here: applanate – where the emerging leaves are pressed flat to each other – and explicative – where the leaves are pressed flat to each other but the edges are folded or rolled back.

This species was named in honour of the Russian botanist Georg Woronow (1874-1931) and originates from the eastern black sea coast - from the ancient provinces of Colchis (for which Colchicum are named) and Lazistan. It favours stony and rocky spots that retain moisture – on river banks, in scrub and on forest margins. Let’s hope we can this replicate here.

All snowdrops are listed on the CITES (Convention on the International Trade of Endangered Species) Appendix II list. This is a list of currently non-threatened species that nevertheless should have their trade monitored and regulated.

Galanthus woronowii was the first snowdrop that the medicinally extremely useful substance galanthamine was isolated from. Galanthamine is currently recommended for the treatment of moderate Alzheimer’s disease by the National Institute of Health and Clinical Excellence (NICE) but is very effective in earlier stages of the disease too. Although originally isolated from this snowdrop, galanthamine can be found in many other members of the Amaryllidaceae such as Narcissus spp., Leucojum aestivum and Crinum amabile. Today, part of the commercial supply of this molecule comes from chemical synthesis, itself an amazing chemical achievement due to the structural complexity of the molecule, and partly from the natural product isolated from different sources across the globe. In China, Lycoris radiata is grown as a crop, in Bulgaria, Leucojum aestivum is farmed and in the UK the humble daffodil, Narcissus ‘Carlton’ is the provider. Look out for these Narcissus in flower in the SCIence garden later in the spring.

The estimated patient population for Alzheimer’s is 5.2 million and the predictions are that galanthamine will be used to treat almost half a million of those sufferers. Sales of Reminyl (galanthamine) in 2003 were £7.9M. One hectare would provide between 15 and 20 tons of bulbs and several hundred tons of bulbs would be required per year to supply all the galanthamine required.

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