Kerikeri teen's anti-bacterial research lands top science prize

Kerikeri's Gillian Toala, 17, has won the Far North's top student science prize for a project examining the anti-bacterial properties of persimmon leaves. Photo / Peter de Graaf

A Kerikeri teenager has won the Far North's top student science prize for discovering persimmon leaves could be put to use in anti-bacterial products such as hand sanitisers.

Gillian Toala, a Year 13 student at Kerikeri High School, won the top award overall in the Top Energy Far North Science and Technology Fair for a project she called Anti-Bact Extract.

This year's science fair was affected by the Covid pandemic, with the public viewing and prizegiving cancelled when Northland was plunged into lockdown.

Judging went ahead, however, and the winners were announced at a series of smaller school events instead.

Gillian's prize was finally presented this week.

The 17-year-old's project focused on tannins, a group of natural compounds which give tea its colour and sometimes stain streams in native bush a deep brown.

Gillian's research had already taught her that tannins had an anti-bacterial effect, and that persimmon leaves were particularly high in tannins.

Given the number of persimmon orchards around Kerikeri, she decided to find out whether the leaves could be put to practical use.

She prepared an extract by drying and crushing persimmon leaves, then mixing the resulting powder with water and ethanol.

She used a swab to collect bacteria from hands, a wound and acne, then placed the bacteria in petri dishes with the extract.

By measuring the ''zone of inhibition'' where bacteria didn't grow she was able to determine how effective the extract was.

She found the extract inhibited the growth of bacteria from all three sources, especially from hands and wounds.

She concluded that persimmon leaf extract could be used as an active ingredient in products such as hand sanitisers and acne creams.

Next year Gillian plans to enrol in biomedicine at Auckland University, with the goal of completing a medical degree and ultimately becoming a surgeon.

Gillian last featured in the Advocate when she won an international virtual reality language competition.

Born in New Zealand to Samoan parents, she is fluent in Samoan and has studied Spanish.

This year's science fair drew 147 projects from 12 schools.

Organisers said the standard was impressive and they were pleased students could have their efforts recognised despite the challenges of Covid.

They were grateful for ongoing support from sponsors, in particular Top Energy, and delighted first-time entrants from Year 6 at Ōhaeawai Primary School won a gold medal for a project on bees.

The top section winners were:

Senior and overall premier winner: Gillian Toala, Kerikeri High School, Anti-bacterial extracts of persimmons.
Year 9-10: Caitlin Renner Austin, Kerikeri High School, Too many masks.
Year 8: Sam Weston, Kerikeri High School, What should your meat patties be fed?
Year 7: William McNulty, Kerikeri High School, CO2 in the classroom.