KARAMŪ

Posted: November 2022

Author: Phil Rasmussen | M.Pharm., M.P.S., Dip. Herb. Med.; M.N.I.M.H.(UK), F.N.Z.A.M.H.
 

Karamū (Coprosma robusta) is a relatively small native tree found throughout Aotearoa New Zealand. It is fast-growing and like mānuka (Leptospermum scoparium), is often planted or seen on bare, infertile sites where it provides shelter for subsequent plantings. Female plants produce masses of small orange berries in late summer. These can be eaten and are enjoyed by birds who contribute to its widespread distribution.

Karamū was widely used in traditional ceremonies and rituals, such as in baptism ceremonies, rites and karakia to the gods, to give sight to the blind. Like most of our other natives, karamū has medicinal value.^1,2,3

Key topical applications of the leaves include aches and pains and broken bones. For these, it was traditionally mixed with other species such as mānuka, kawakawa (Piper excelsum) and koromiko (Hebe stricta). As with so many of our wonderful indigenous plants, karamū also has uses as an antimicrobial. It can be applied to sores and boils, with other herbs such as mānuka and calendula (Calendula officinalis).

Traditionally karamū was sometimes taken internally for conditions of the genito-urinary system. It particularly helps alleviate urinary problems such as difficult urination and urinary retention. Decoctions of the leaves, often combined with kawakawa leaves to enhance diuretic activity, were prepared and given as diuretics and to relieve bladder inflammation. Preparations can also be used for benign prostatic hypertrophy, and further studies for this seem warranted. Women would also sometimes use preparations of karamū with tataramoa (Rubus cissoides), to help alleviate period pain or dysmenorrhoea.²

Other prominent uses are for stomach ache, where it combines well with kawakawa, and also for nausea and vomiting. Recent research has reported anti-inflammatory and anti-tumour effects of asperuloside (an iridoid constituent commonly found in Rubiaceae family plants, including karamū and Morinda citrifolia, or noni). This may contribute to protective effects against colorectal cancer, through the activation of vitamin D receptors.⁴

Karamū also seems to have a mild diaphoretic action useful in the treatment of fevers and colds. It also has antimicrobial effects contributing to its benefits in treating respiratory tract conditions in general. Inhalations or vapour baths of karamū with other native plants such as kawakawa, and korokio (Corokia cotoneaster) were said to revive airways that had sometimes ceased to move. A pleasant syrup can be made from ripe berries, which are undoubtedly rich in vitamin C and many other antioxidant and healthy polyphenolic compounds. The use of dried berries as a coffee substitute (Coffea arabica also being in the Rubiaceae family), sadly doesn’t seem to produce the same effects, although probably has some health benefits.

Case reports exist of karamū having beneficial effects in patients with Type 2 Diabetes mellitus, although no research into this appears to have been undertaken to date. Inhibition of pancreatic α-amylase by various karamū constituents such as ursolic acid, coumarins such as scopoletin and iridoids such as asperuloside, has been implicated in other studies, as possible mechanisms of action.⁵

Karamū is one of the most readily available native plants, and as the days grow longer and its leaves and berries grow faster and faster, it is certainly a medicinal tree to notice and pay more attention to.


References:

1. Brooker SG, Cambie RC, Cooper RC. New Zealand Medicinal Plants. Heinemann Publishers, Auckland, 1981.
2. Riley M., “Maori Healing and Herbal: New Zealand Ethnobotanical Sourcebook”, Viking Sevenseas, Paraparaumu, N.Z., 1994.
3. Rasmussen PL, New Zealand Native plants and their clinical applications for respiratory conditions, Phytomed Seminar, June 2015.
4. Lu Y, Guan T, Xu S, et al. Asperuloside inhibited epithelial-mesenchymal transition in colitis associated cancer via activation of vitamin D receptor. Phytomedicine. 2022;101:154070.
5. Lolok N, Sumiwi SA, Muhtadi A, et al. Molecular docking and molecular dynamics studies of bioactive compounds contained in noni fruit (Morinda citrifolia L.) against human pancreatic α-amylase. J Biomol Struct Dyn. 2022;40(15):7091-7098.