Totara: a versatile native medicine
Posted: February 2023
Author: Phil Rasmussen | M.Pharm., M.P.S., Dip. Herb. Med.; M.N.I.M.H.(UK), F.N.Z.A.M.H.
A special value is placed on the tōtara tree (Podocarpus totara) in Māori culture and traditional practices, and it is regarded as a principal member of the company of superior and majestic trees (“rakau rangatira’). It is a solid and generally straight-growing conifer which can reach heights of up to 40 m tall, being the second largest tree in Aotearoa New Zealand (NZ).1,2 Podocarpus spp are found throughout Aotearoa NZ, Australia, Asia, central and south America and Africa.
Tōtara is renowned for the lightness and longevity of its wood, which was widely used for carvings, canoes and fortification, by Māori and early European settlers as a building material. Of interest is, that it seems to have the ability to survive environmental attacks and degradation, and to last a long time. These traits and its large height and wide girth combined with its water-resistant properties are a reflection of the power of its secondary metabolites and antioxidant properties. This makes it ideal to carve waka (canoes). Many great waka made from tōtara were used daily and in warfare by early Māori, and have crossed the Pacific Ocean.
There are also several closely related species, including Hall’s tōtara or mountain tōtara (podocarpus laetus). Previously known as Podocarpus hallii and Podocarpus cunninghamii, it tends to be found more in higher altitudes, and has thinner bark and longer juvenile leaves. The so-called golden tōtara, is a natural hybrid of Podocarpus acutifolius (needle-leaved tōtara) with Podocarpus tōtara, and I can testify can easily be grown from cuttings. Two specimens mark the entrance to Phytomed’s premises in Avondale, Auckland.
Many different varieties of Podocarpus tōtara occur throughout Aotearoa, with regional and undoubtedly phytochemical and other variations. It can grow in almost any soil and survive in open spaces. Given our country’s need to move away from an over-dependence on Pinus radiata as a forestry species, tōtara is probably one of the best native trees to be planted for timber.
Phytochemistry
As with other Podocarps, tannins are present in all parts of the tree, particularly the bark and leaves. Diterpenes including totarol, totaradiol and its dimer podototarin, are prominent constituents, and likely to contribute to many of its medicinal applications.3-5
Medicinal uses
The small bright red berries of tōtara were once a valued food source, and Māori collected and ate these, which have a relatively sweet and juicy but somewhat acquired slightly turpentine-like flavour. These were also said to have laxative properties.
Strips of bark were also used as splints, to help immobilise joints when bones were broken. Layers of the softer inner bark were first applied, sometimes with lower parts of harakeke leaves or kahakaha as padding, then the harder outer bark tied on as the outer layer.
All parts of the tree are moderately astringent, and bark and leaves were burnt and the smoke used to heal sores and skin complaints, as well as haemorrhoids. The bark was also boiled and used to reduce a fever, often combined with Mānuka. Tōtara bark preparations can be particularly useful for topical skin conditions, wounds, abrasions, cuts and inflammatory conditions such as eczema and acne.3-5
Totarol
Some of the interest in tōtara and its medicinal applications relates to totarol, the diterpenoid compound found in the heartwood and sap of P totara, as well as that of the Asian tree Podocarpus nagi. Totarol is extracted using a patented method from the heartwood of trees and is a powerful antioxidant and antimicrobial.
Antibacterial activity against methicillin-resistant Staphylococcus aureus was first reported for totarol by Japanese researchers in 1992.6 This anti-Staph activity is now known to include methicillin-resistant, epidemic, community and multi-drug-resistant strains (Smith 2007). Sub-inhibitory concentrations enhance the antibacterial activities of several antibiotics, suggesting it is an efflux pump inhibitor.7, 8
Antibacterial activity against other pathogens including Bacillus subtilis, Brevibacterium ammoniagenes, Streptococcus mutans and Propionibacterium acnes, has also been reported. One of the key acne-causing bacteria, Propionibacterium acnes, is particularly sensitive. However, totarol has less activity against gram-negative bacteria such as Pseudomonas aeruginosa, E coli, or Enterobacter aerogenes.
Totarol’s strong antioxidant and antimicrobial activities have made it useful as a natural preservative in many human and animal natural health products, over the past 30 years. Applications in animal and livestock health, and as a preservative to help prevent bacterial growth in foods and cosmetics, have also been commercially utilised and further researched in recent years.9
Future
The recent climatic events in Aotearoa and the damage caused by overdependence on a single species of exotic trees for our local forestry industry has created a case to further trial and expand tōtara as a plantation forestry tree. It also raises a question around funding more research into its many possible medicinal applications, based upon traditional uses and science.
References:
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Tōtara – Podocarpus totara, Meaning of Trees, (2019), Link: https://meaningoftrees.com/2019/02/28/totara-podocarpus-totara.
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Botanist Philip Simpson shares his love of totara, ThisNZLife, Link: https://thisnzlife.co.nz/video-botanist-philip-simpson-shares-love-totara/
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Brooker SG, Cambie RC, Cooper RC. New Zealand Medicinal Plants. Heinemann Publishers, Auckland, 1981.
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Riley M., “Maori Healing and Herbal: New Zealand Ethnobotanical Sourcebook”, Viking Sevenseas, Paraparaumu, N.Z., 1994.
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Rasmussen PL, New Zealand Native plants. Part 1. Phytomed Webinar, September 2018.
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Kubo, I., Muroi, H., & Himejima, M. (1992). Antibacterial activity of totarol and its potentiation. Journal of natural products, 55(10), 1436–1440.
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Micol V, Mateo, C. R., Shapiro, S., Aranda, F. J., & Villalaín, J. (2001). Effects of (+)-totarol, a diterpenoid antibacterial agent, on phospholipid model membranes. Biochimica et biophysica acta, 1511(2), 281–290
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Smith, E. C., Kaatz, G. W., Seo, S. M., Wareham, N., Williamson, E. M., & Gibbons, S. (2007). The phenolic diterpene totarol inhibits multidrug efflux pump activity in Staphylococcus aureus. Antimicrobial agents and chemotherapy, 51(12), 4480–4483.
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Shi, C., Che, M., Zhang, X., Liu, Z., Meng, R., Bu, X., Ye, H., & Guo, N. (2018). Antibacterial activity and mode of action of totarol against Staphylococcus aureus in carrot juice. Journal of food science and technology, 55(3), 924–934.
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