Phytotherapy for Pain – NZ Natives

Pain is something experienced by all humans at some stage, but more regularly by a large percentage of the population, and it can have a major impact on the person’s quality of life.

With aging populations, chronic painful inflammatory joint conditions are becoming more common. These, as well as regular instances of connective tissue or muscle pain following sprains, fractures, cuts, or bruises, means the need for interventions to help with pain management is high on the list of human needs. While analgesic drugs can be very effective, they are also associated with disadvantages such as a high predisposition to adverse events, or a risk of dependency with ongoing use.

Phytotherapy has always been applied for pain management by different cultures traditionally around the world. While the opium poppy has the strongest reputation as an analgesic, there are many others that can be used, including some of our native species.

Laurelia novae-zelandiae (Pukatea)

Bark of the giant podocarp pukatea was traditionally used for neuralgia, sore stomachs, and toothache.¹ Its constituents include isoquinoline alkaloids such as pukateine, laureline and laurepukine, which have a similar structure to morphine. Pukatea preparations have been widely used for pain management by rongoā Māori practitioners and by medical herbalists in Aotearoa New Zealand and in Australia; although, sourcing sufficient bark in a sustainable manner has proven difficult in recent years.

As with other strong analgesics, doses should be started low and titrated up if necessary. The exception to this is in cases of severe acute pain. Being an alkaloid-rich phytomedicine, pukatea is also quite bitter, which is a consideration for some patients. Like opiate-derived medicines it may produce constipation or central nervous system impairment if large doses are taken.

Pukatea has successfully been used for a wide range of both acute and chronic pain conditions, in doses ranging from 3 to 15 mL of a 1:2 hydroethanolic liquid extract, as both a simple treatment, and mixed with other plant extracts.

Pseudowintera axillaris and Pseudowintera colorata (Horopito)

A leaf decoction was used ‘to allay inward pain’ and was once called a ‘Māori painkiller’.² This speaks volumes about some of its traditional applications, which included topical use for conditions such as toothache and swollen joints, and internally for stomach ache and headache.^{1, 3}

Polygodial, a strong peppery tasting sesquiterpene dialdehyde compound, is considered a prominent active constituent of horopito.⁴ Animal studies have shown it to have pronounced and long-lasting anti-nociceptive (analgesic) activity, effects. This have been related to possible influences on opiate, serotonergic and α-1-adrenoceptors, as well as modulation of glutamatergic neurotransmission.^5-7

Modulation of transient receptor potential vanilloid 1 (TRPV1) receptor’s lead to anti-inflammatory and anti-hyperalgesic responses. Reduced sensations of chemical and thermal inflammatory pain, and primary afferent nerve fibres responsible for pain transmission, has been correlated with polygodial.^{3, 8-10}Such effects also contribute to the counterirritant or rubefacient actions of various warming or pungent plants, such as capsicum or mustard, used topically for symptomatic relief in inflammatory muscle or joint pain.

While more research is needed on the pharmacology of horopito and its applications in painful conditions, it has often been found to be helpful for both acute and chronic conditions. This is particularly where stomach pains or an imbalance in the gut microbiome is thought to be present.

Macropiper excelsum (Kawakawa)

This is another good anti-inflammatory. With pain being related to excessive inflammation, it can make a useful ingredient in formulations aimed at pain management. A key application is for acute pain in the stomach and lower gastrointestinal tract, but it can also be incorporated as part of the treatment of other chronic inflammatory conditions. Topical applications, to reduce the inflammation of skin conditions such as eczema, psoriasis, and painful skin rashes, also gives it a place amongst our selection of medicinal plants to assist with pain management.^{11, 12}

Kawakawa fruits can be chewed, and the saliva swallowed for toothache, while poultices and other local applications were also used by early Māori for headaches, nettle stings, and rheumatic pains.^{1, 11}

While the volatile oil of kawakawa contains constituents related to eugenol, a primary constituent with analgesic activity found in cloves, amide constituents such as pellitorine and various piperine derivatives are likely to contribute to mild analgesic properties in some types of pain.^12,13 Modulation of TRPV1 receptors by pellitorine and other constituents may also be involved.¹⁴

Dodonaea viscosa (Akeake)

Akeake is a small, evergreen tree used in many types of traditional medicine in various countries, including Aotearoa New Zealand, Australia, India, Indonesia, various Pacific islands, Central and South America, and Africa.

Like kawakawa, akeake is a useful anti-inflammatory for painful joint conditions.¹⁵ In Australia, Dodonaea (known as ‘hopbush’) is used for painful swellings and rheumatic joints, while in India and Pakistan, it is a popular topical application for musculoskeletal ailments, particularly where pain is a prominent symptom.^16,17 Tincture, and other preparations are taken internally and applied topically for gout, rheumatism, and inflammations in Mexico, Peru and Panama.

The chewed leaves and juice are traditionally applied to stingray and stonefish stings by Aboriginals in northern Queensland.¹⁶ Various plant parts, including stems, leaves, and bark are often heated when preparing such traditional preparations.

In vitro animal model studies of arthritis have shown the diterpenoid compound hautriwaic acid to be contributory to these anti-inflammatory and local anaesthetic properties.¹⁸

Other pain-relieving natives

The link between inflammation and pain, and the anti-inflammatory properties of the many native plants, such as kohekohe, kānuka, mānuka, makomako, rimu, manono and karo, identifies the ability of many of these to assist in some cases of both acute and chronic pain management.

From both a topical application perspective, for burns, musculoskeletal pain, or neuropathic pain including headaches or neuralgia, or when taken systemically for generalised pain, dysmenorrhoea, or digestive pain, several of our native species deserve consideration and more research investigation.
 

References:

1. Riley M, Maori Healing and Herbal, New Zealand Ethnobotanical Sourcebook, Viking Sevenseas NZ, Paraparaumu, New Zealand, 1994.
2. Featon EH. Art Album of New Zealand, Vol 1. Trubner & Co, London, 1889.
3. Rasmussen PL, Pseudowintera spp.(Horopito): a monograph. Australian Journal of Herbal Medicine. 2014;26(4):150.
4. McCallion FR et al, Antibiotic substances from New Zealand plants: II. Polygodial, an anti-candida agent from Pseudowintera colorata. Planta Med 1982; 44(3):134-138.
5. Mendes GL et al, Assessment of mechanisms involved in antinociception caused by sesquiterpene polygodial. J Pharmacol Exp Ther 292 (1):164-172, Jan 2000.
6. Martini LH et al, The sesquiterpenes polygodial and drimanial in vitro affect glutamatergic transport in rat brain. Neurochem Res 31(3):431-438, Mar 2006.
7. Martini LH et al, Naturally occurring compounds affect glutamatergic neurotransmission in rat brain. Neurochem Res 32(11):1950-1956, Nov 2007.
8. Andre E et al, Pharmacological characterisation of the plant sesquiterpenes polygodial and drimanial as vanilloid receptor agonists. Biochem Pharmacol 71(8):1248-1254, 2006.
9. Andre E et al, Evidence for the involvement of vanilloid receptor in the antinociception produced by the dialdehydes unsaturated sesquiterpenes polygodial and drimanial in rats. Neuropharmacol 2004; 46(4):590-597.
10. Szallasi A et al, TRPV1: a therapeutic target for novel analgesic drugs? Trends Mol Med 2006; 12(11):545-554.
11. Rasmussen, P.L., Kawakawa: a monograph. Phytonews, published by Phytomed Medicinal Herbs Ltd, 7, 1-7, Sept 2000. ISSN 1175-0251
12. Rasmussen, P.L., Kawakawa: a promising New Zealand native plant. Pharmacy Today, August 2021. ISSN 1170-1927
13. Sell AB, Carlini EA, Anaesthetic action of methyleugenol and other eugenol derivatives. Pharmacology 1976;14(4), 367-377.
14. Naik GG, Uniyal A, Chouhan D, Tiwari V, Sahu AN. Natural Products and some Semi-synthetic Analogues as Potential TRPV1 Ligands for Attenuating Neuropathic Pain. Curr Pharm Biotechnol. 2022;23(6):766-786.
15. Rasmussen PL, NZ Native Plants: Part 2. Webinar, by Phytomed Medicinal Herbs Ltd, October 2018.
16. Yeshi K, Turpin G, Jamtsho T, Wangchuk P. Indigenous Uses, Phytochemical Analysis, and Anti-Inflammatory Properties of Australian Tropical Medicinal Plants. Molecules. 2022;27(12):3849.
17. Shanmugavasan A, Ramachandran T. Investigation of the extraction process and phytochemical composition of preparations of Dodonaea viscosa (L.) Jacq. J Ethnopharmacol. 2011;137(3):1172-1176.
18. Salinas-Sánchez DO, Zamilpa A, Pérez S, et al. Effect of Hautriwaic Acid Isolated from Dodonaea viscosa in a Model of Kaolin/Carrageenan-Induced Monoarthritis. Planta Med. 2015;81(14):1240-1247.