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Biochemistry

The chemistry of poppies: colours and opium

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11 November is Remembrance Day. As the flowers that grew on the battlefields of WWI, poppies are used as the symbol for this day. This graphic takes a look at the chemical compounds behind their colours, as well as some of the useful medical compounds that can be obtained from different types of poppies.

As with many other flowers, the blood-red colour of the common poppy is due to anthocyanins. They contain anthocyanins which include cyanidin 3-sophoroside and cyanidin 3-glucoside. Some variations in colour are due to varying concentrations of these anthocyanins.

For some poppy species, colour variations also have a more curious chemical basis. The Iceland poppy, alpine poppy and Welsh poppies are all notable for having varieties with yellow petals. This yellow colouration is not due to anthocyanins, but another type of pigment called nudicaulins.

Nudicaulins were first isolated over 100 years ago, but their structure wasn’t confirmed until 2013. An unusual reaction between anthocyanins and indole is responsible for their creation in these poppies. These precursors are produced by many flowering plants, so why they’re only found in certain types of poppies is still a mystery.

Away from their colours, poppies are well-known for their association with opium. Opium is the milky liquid obtained from opium poppy seed pods which contains powerful alkaloid painkillers including morphine and codeine. The more potent painkiller, diamorphine, can be made using morphine as a starting point. Diamorphine is more commonly known as heroin.

Other poppies contain alkaloid compounds, too. The common poppy contains various alkaloids, including rhoeadine and rhoeagenine. However, these alkaloids only have very mild pain-killing properties and unlike the opium poppy alkaloids they are non-addictive. In fact, rhoeadine is one of a number of compounds that have been investigated for treatment of morphine dependence.

There’s lots more on the various compounds used as painkillers in this previous post.

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