Natives hold the key

Almost 400 New Zealand native plants contain promising medicinal compounds, a new type of analysis has found. The study focused on plants already known to have medicinal properties based on earlier studies and Ma¯ ori traditions, said lead researcher Lisa Pilkington, a research fellow in the School of Chemical Sciences at the University of Auckland.

These known medicinal compounds were then categorised using a fairly new system.

About 10 per cent of the compounds were considered ‘‘lead-like’’ – the most promising category. More than half were considered to be in the ‘‘druglike space’’ – the second-most promising category. And about 75 per cent were in the ‘‘known drug space’’ – the broadest category.

These new categories point researchers at the most promising compounds for more intensive study, said co-author Johannes Reynisson, also of the University of Auckland.

The next stage of research would likely look at the most promising 20 to 30 compounds and the stage after that might more closely analyse two or three compounds, he said.

A 2014 study at Tufts University in Boston found outof-pocket costs to bring new medicines to market were US$1.4 billion. Other studies have found that nine in 10 potential medicines fail because they are ineffective, unsafe or otherwise unsatisfactory.

Still, ‘‘New Zealand flora presents an as-yet untapped and rich source of potential drug leads and future therapeutics’’, concludes their paper. It was published in Chemistry, an Asian journal.

‘‘Oral availability’’ was one of the most sought after attributes of the compounds. It meant they could be packaged into pills, which patients prefer over injections.

‘‘This is a definite area for further investigation, particularly because of the positive results in this initial study.’’ Lisa Pilkington

Compounds with low molecular weight were also preferred because future medicine makers might need to add to the molecules to make an effective drug. The paper calls this the ‘‘optimisation process’’.

Many of the preferred compounds were similar to existing commercial drugs, Reynisson said in an interview. They were not duplicates, but similar enough that existing drugs could be used as reference points.

There are about 2000 different species of plants in Aotearoa, with at least 80 per cent endemic to this country, Pilkington said in an email.

Other chemists specialise in discovering compounds that have never been investigated before and may be biologically active, that is, have medicinal properties, said Pilkington. ‘‘This research is difficult and time-consuming [and] without it we would not have the data to work with.’’

Their analysis was largely done on computers. The researchers did not possess any of the molecules, let alone the plants and did not conduct field work.

Reynisson said the known compounds were derived from the book, New Zealand Medicinal Plants, published in 1981, as well as books on Rongoa¯ Ma¯ ori.

Pilkington and colleagues hoped that consultation with Ma¯ ori would be at the ‘‘forefront of future, expanded investigation into New Zealand plants’’.

‘‘Because we only focused on plants that are definitely known to exhibit medicinal properties, we did not investigate all New Zealand plants. This is a definite area for further investigation, particularly because of the positive and encouraging results we saw in this initial study,’’ Pilkington said.