Two of the bio active molecules found in the leaves are Myristicin and Diayangambin. Myristicin is responsible for the anti-inflammatory and anti-microbial effect that the leaves have and this effect has been consistently shown in various studies undertaken (Richardson 2015).
Piper excelsum (formerly known as Macropiper excelsum), commonly known as Kawakawa is a small tree native to New Zealand that has strong ties to traditional Maori medicine (Rongoā Māori). It grows in the warmer parts of the country in shady areas (Macropiper excelsum 2011).
Traditionally the leaves were used by Maori for pain relief, cuts, bruises, inflammation as well as a variety of skin ailments. Today Kawakawa is used as an insect repellent and due to its anti-inflammatory properties, it is used to alleviate a variety of health conditions (TERRAIN 2018).
"Macropiper excelsum. Kawakawa" Archived 2016-08-11 at the Wayback Machine., Ngā Tipu Whakaoranga - Māori Plant Use Database, Landcareresearch.co.nz
TERRAIN. Feb 05. Accessed 03 28, 2020. http://www.terrain.net.nz/friends-of-te-henui-group/trees-native-botanical-names-m-to-q/kawakawa.html
Richardson, Alistari T B. 2015. "Hot new chemistry from a kiwi pepper tree." Chemistry in New Zealand 90-93