The NZ Natives and Skin

 

Author: Katie Donnelly, Adv Dip HSc Naturopathy

NZ Natives and Skin

New Zealand Natives and Skin

New Zealand (NZ) native herbs have been used to calm and treat skin conditions for centuries. Rongoā rākau, plant medicine, was practised by indigenous Māori to ease pain, and treat infections, war wounds and burns. Today, native NZ herbs remain some of the top choices for the treatment of skin conditions. Traditional uses are supported by growing research, highlighting the importance of indigenous knowledge in phytomedicine.¹

Microbial infections

Traditionally, Leptospermum scoparium (mānuka) leaves were crushed and placed on itchy wounds, and boiled and drank as an analgesic. The bark was also used directly on dermatological diseases. Mānuka is now commonly known as a potent plant honey variety, due to methylglyoxal and the significant actions of mānuka herb.²

This herb is indicated for viral, bacterial, parasitic, and fungal infections, both chronic and acute in nature. Recent animal model studies identified flavesone and leptospermone constituents as inhibiting herpes simplex virus type 1 (HSV-1) and type 2. HSV-1 and HSV-2 are associated with cold sores and venereal diseases, respectively. Prevention of viral replication of HSV-1 was recorded as 41% with manuka, where cells were pretreated. Further uses for Hand, Foot, and Mouth disease have also been suggested.²

As an antibacterial, mānuka acts on Gram positive and negative bacteria, by attacking the cellular membrane and preventing biofilm formation. Furthermore, triketones have been isolated as preventing morphology of methicillin-resistant Staphylococcus aureus. This bacterium is increasingly implicated in conditions such as impetigo, particularly in a hospital setting. ²

Mānuka has also shown to reduce the intensity of acne vulgaris, alongside Podocarpus totara (totara). Revered as rakau rangatira, a chiefly tree, totara provided shelter to Māori and was used for waka throughout Māori history.

Recent research has identified antimicrobial actions from totara against Propionibacterium/ Cutibacterium acnes, a common bacterium in acne development.³ While P. acnes exists as a commensal micro-organism, and can promote skin health, it can become opportunistically pathogenic. The phenolic diterpenoid, totarol, in totara, controls bacterial replication by interfering with protein expression and bacteria metabolic enzymes.⁴ This has also been effective against Methicillin-resistant Staphylococcus aureus (MRSA).³

Wound healing

Used topically as a poultice for cuts and wounds, Phormium tenax (harakeke) is also suitable for bruises and varicose veins. Root preparations, rich in anthraquinones and tannins, are effective in ringworm treatment when taken internally or applied topically. The leaf polysaccharides then provide soothing and moisturising actions.

Plant polysaccharides have shown notable improvements in the rate of epithelial regeneration. In both clinical and animal model studies, polysaccharides encouraged faster wound healing and reduced bacterial adhesions. Similarly, studies showed increased ultra-violet sun protection, skin hydration, and moisture.⁵

Harakeke leaves were traditionally combined with Hoheria populnea (hoheria) to calm burns via its well-known hydrocolloid properties. While hoheria bark was often used, mucilage from the leaf has been identified as a sustainable alternative.⁶

Taken internally, or added to a base cream, Dodonaea viscosa (akeake) also encourages skin restoration.⁷ Hydroethanolic extracts of akeake contain high concentrations of quercetin and kaempferol, contributing to this action. The potent antioxidants promote rapid wound healing, including collagen and skin cell reformulation, with restored blood flow.⁸ Clinical studies have demonstrated improvements in pruritis, redness, swelling, and cell apoptosis.⁹

This further supports customary uses of akeake, where the ground root was used topically to cover skin lesions. These antioxidant constituents are also identified in Coprosma robusta (karamu).

Applied topically, Pseudowintera colorata and Pseudowintera axillaris (horopito) has also demonstrated significant healing actions for cuts, bruises, and inflammatory skin conditions. This was specifically noted for ailments causing pain.

Internal support

Perhaps one of the most widely known native plants for skin conditions is Macropiper excelsum (kawakawa). The heart-shaped leaves were originally used as a poultice to heal wounds and chewed to provide local analgesia. Boiled leaves were also consumed to ease arthritic pain, reduce bruising, and to treat ringworm infections.¹

As a circulatory stimulant, kawakawa increases peripheral blood flow, particularly important in preventing diabetic ulceration. Furthermore, glucose regulation from oral intake showed alteration in glucose transporter-4 expression and improved glucose sensitivity, in recent studies. Imbalanced blood sugars contribute to impaired skin angiogenesis and reduced macrophage phagocytosis.¹⁰ As such, kawakawa can support reduced ulcer infection through glucose modulation and normalisation of endothelial cell renewal.¹¹

Myristicin, a primary constituent, has also shown to reduce interleukin-6 and interleukin-10 cytokines, contributing to reduced inflammation. Vitexin, an apigenin, has been noted to influence tumour necrosis factor-alpha through potent antioxidant activity.¹²

Summary

Many of the New Zealand natives can be used to support skin health and recovery. From infections and wounds, to addressing blood sugar imbalances, native phytomedicine helps address numerous skin conditions.

References

1. Best Practice Journal New Zealand. Demystifying Rongoa Maori Traditional Maori Healing. 2008; (13): 32-36. Available from: https://bpac.org.nz/bpj/2008/may/docs/bpj13_rongoa_pages_32-36.pdf
2. Mathew C, Tesfaye W, Rasmussen P, Peterson GM, Bartholomaeus A, Sharma M, Thomas J. Mānuka Oil-A Review of Antimicrobial and Other Medicinal Properties. Pharmaceuticals (Basel). 2020 Oct 26;13(11):343. Available from: https://doi.org/10.3390/ph13110343
3. Kim MB, O'Brien TE, Moore JT, Anderson DE, Foss MH, Weibel DL, Ames JB, Shaw JT. The Synthesis and Antimicrobial Activity of Heterocyclic Derivatives of Totarol. ACS Med Chem Lett. 2012 Aug 28;3(10):818-822. Available from: https://doi.org/10.1021/ml3001775.
4. Tavares W, Seca A. The Current Status of the Pharmaceutical Potential of Juniperus L. Metabolites. Medicines 2018;5:81. Available from: https://doi.org/10.3390/medicines5030081.
5. Albuquerque PBS, de Oliveira WF, dos Santos Silva PM, dos Santos Correia MT, Kennedy JF, Coelho LCBB. Skincare application of medicinal plant polysaccharides — A review. Carbohydrate Polymers. 2022; 244(118824). Available from: https://doi.org/10.1016/j.carbpol.2021.118824.
6. Carnachan SM, Bell TJ, Hinkley SFR, Sims IM. Polysaccharides from New Zealand Native Plants: A Review of Their Structure, Properties, and Potential Applications. Plants (Basel). 2019 Jun 9;8(6):163. Available from: https://doi.org/10.3390/plants8060163.
7. Yeshi K, Turpin G, Jamtsho T, Wangchuk P. Indigenous Uses, Phytochemical Analysis, and Anti-Inflammatory Properties of Australian Tropical Medicinal Plants. Molecules. 2022 Jun 15;27(12):3849. Available from: https://doi.org/10.3390/molecules27123849.
8. Subramanian S, Duraipandian C, Alsayari A, Ramachawolran G, Wong LS, Sekar M, Gan SH, Subramaniyan V, Seethalakshmi S, Jeyabalan S, Dhanasekaran S, Chinni SV, Mat Rani NNI, Wahab S. Wound healing properties of a new formulated flavonoid-rich fraction from Dodonaea viscosa Jacq. leaves extract. Front Pharmacol. 2023 Feb 2;14:1096905. Available from: https://doi.org/10.3389/fphar.2023.1096905
9. Park SJ, Kim DW, Lim SR, Sung J, Kim TH, Min IS, Choi CH, Lee SJ. Kaempferol Blocks the Skin Fibroblastic Interleukin 1β Expression and Cytotoxicity Induced by 12-O-tetradecanoylphorbol-13-acetate by Suppressing c-Jun N-terminal Kinase. Nutrients. 2021 Sep 1;13(9):307 Available from: https://doi.org/10.3390/nu13093079.
10. Hazeline KJ, Peter S. The Potential of Anti-Diabetic Rākau Rongoā (Māori Herbal Medicine) to Treat Type 2 Diabetes Mellitus (T2DM) Mate Huka: A Review. Frontiers in Pharmacology. 2020; 11. Available from: https://www.frontiersin.org/articles/3389/fphar.2020.00935
11. Spampinato SF, Caruso GI, De Pasquale R, Sortino MA, Merlo S. The Treatment of Impaired Wound Healing in Diabetes: Looking among Old Drugs. Pharmaceuticals (Basel). 2020 Apr 1;13(4):60. Available from: https://ddoi.org/10.3390/ph13040060.
12. Ramzan F, Jayaprakash R, Pook C, Foster M, Miles-Chan JL, Mithen R. Acute Effects of Kawakawa (Piper excelsum) Intake on Postprandial Glycemic and Insulinaemic Response in a Healthy Population. Nutrients. 2022 Apr 14;14(8):1638. Available for: https://doi.org/10.3390/nu14081638.