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Propagating and growing Sutherlandia frutescens in Australia: an overlooked opportunity?

Introduction

Sutherlandia frutescens is a medicinal plant with a long history of traditional use in South African medicine for numerous conditions including cancer. More recently it has been recognised for its role in the management of human immunodeficiency virus (HIV), tuberculosis (TB) and diabetes. It has also been used traditionally as an adaptogenic herb for chronic fatigue syndrome, gastro-intestinal complaints including gastritis and for arthralgia (www.sutherlandia.org). Vernacular names for S. frutescens include cancer bush (English) or Kankerbos (Afrikaans).

Despite its long traditional use, S. frutescens is not commonly used among herbal medicine practitioners in Australia, probably due to its current lack of availability from herbal suppliers as well as the fact that it is generally not included in materia medicae at an undergraduate level. S. frutescens is ideally suited for propagating and growing in various Australian climates. The dried plant material can then be easily used for therapeutic purposes in the forms of tea, capsules or liquid extracts. This paper will focus on the botany, growing and harvesting of the aerial parts of S. frutescens, while touching briefly on its therapeutic uses.

Botany

The genus Sutherlandia was named after the Scottish botanist James Sutherland (1639-1719), although the genus name Lessertia is also currently recognised. S. frutescens is a perennial leguminous shrub with pinnately compound leaves and bright red flowers which produce inflated bladdery pods. Given adequate conditions it will grow to approximately 2m in height (Van Wyk et al, 2004).

Propagation, growing and harvesting

This plant is easily propagated from seed. It is often a pioneer plant in the wild and can withstand extreme conditions, including a hot, dry climate; however, waterlogged soil is not tolerated. Seeds are collected from the dried mature seed pod. The seeds are approximately 3mm in length, oval shaped, flat and dark brown in colour.

Seeds should be propagated directly in soil or a seed raising mix in spring, or struck from semi-hard wood cuttings in early summer. They will take around 2-3 weeks to germinate which may be enhanced by soaking in warm water for a few hours or overnight.

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Sutherlandia grows well in most soil types, from a light sandy soil to the heavy clay soil found in Toowoomba, SE Queensland; however, it prefers neutral or acidic soil types. Full sun position is ideal and it is best protected from strong winds. Toowoomba can get very cold during the winter, occasionally reaching 0[degrees]C at night with regular frosts; however, this doesn't appear to adversely effect the growth of the plant (some authors on Sutherlandia state that it doesn't tolerate frost, but this has not been my experience with growing this plant). Over winter the plant lies dormant with no new growth until the following spring.

The Toowoomba summer can be very hot, with daytime temperatures reaching the high 30's. Even in a hot, dry climate, Sutherlandia only requires minimal watering and doesn't show leaf wilt or appear to be adversely affected. If grown in daily, direct sun, it should be planted in a minimum space of 2m x 2m to allow for expanded growth.

Aerial parts can be harvested from the first year onwards. It is best to take only about a third or so off the length of the stems when pruning as this plant will not tolerate heavy cut back. Sutherlandia behaves as a woody perennial rather than an herbaceous perennial and a moderate pruning will produce thick new growth the following season.

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Compound leaves are best removed from the stalk for drying; however, leaf stalk can also be cut into small sections for drying and included in the final material. Alternatively, branches can be removed and hung complete for drying (although this prolongs drying time) and aerial parts will dry easily without bruising or discolouring. Once dry, the leaf material is easily removed from the stem if desired (although the stem can also be included in medicinal material). Flowers are mostly used for seed production but may also be included as medicinal aerial part. Aerial parts should be dried thoroughly and assessed for any microbial or insect contamination prior to storage in an airtight jar or bag.

Two to three large S. frutescens shrubs should easily supply enough raw materials for patient supply as the daily dose is relatively small.

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Clinical use

Although this is not the focus of this paper, some of the traditional internal uses of the aerial parts of S. frutescens for pathology include:

* Cancer

* Infectious diseases: viral and bacterial infections (including tuberculosis), generalised feverish conditions, urinary tract infection

* Inflammatory conditions e.g. asthma, rheumatism

* Gastrointestinal tract conditions e.g. indigestion, anorexia, gastritis, peptic ulcers, dysentery (www. sutherlandia.org, Van Wyk et al, 2004).

Sutherlandia has a strong, bitter flavour which would, in part, explain some of its gastrointestinal indications. Its use in cancer and infectious disease may be due to its immune stimulating properties. There is some basic in vitro evidence showing that plant extracts have direct antimicrobial properties against Pseudomonas, Candida spp. and Staphylococcus aureus (www.sutherlandia.org).

S. frutescens has also been traditionally used topically for the management of burns, wounds and inflammatory skin conditions (Van Wyk et al, 2004). For a further review of the medicinal uses of S. frutescens, please see the Australian Journal of Herbal Medicine (AJHM) articles by Dr Nigel Gericke (AJHM Vol 14, issue 2. 2002 and AJHM Vol 13, issue 1. 2001)

Constituents

There have been a number of in vitro studies of Sutherlandia and its chemical constituents have been well identified. The main pharmacological constituents include: L-canavanine, pinitol, GABA and triterpenoid glucosides (www.sutherlandia.org). Although there is a strong history of traditional use for Sutherlandia, there have unfortunately been no clinical trials in humans to further validate any indications.

Dose:

* 9mg/kg/day (Seier et al. 2002) (equates to about 200mg tds in a 70kg adult)

* 1-2g per day of dry herb as tea, decoction or tablet/ capsule (Van Wyk et al. 2004)

* Dose range appears to be 1-2 x 300mg capsules TDS

Summary

I have grown Sutherlandia from seed on numerous occasions and it is a very rewarding shrub to grow. It grows quickly and, being a member of the legume family, is said to be beneficial for nitrogen fixation in the soil (although I have never directly observed nitrogen nodules on the roots). It produces an abundance of beautiful red flowers in summer that stand out in the garden. The seed is easily harvested from this plant and used for propagating the next season.

One to two large plants should supply all the raw material needed to manufacture sufficient capsules. As mentioned above, the taste of this plant is quite bitter so Sutherlandia tea is only for the very committed. As yet, there are no suppliers of Sutherlandia raw material, capsules or liquid extracts in Australia, so these must currently be obtained from overseas. Good quality human trials are also needed to corroborate traditional usage.

References

van Wyk, BE. Wink, M. 2004. Medicinal Plants of the World. Timber Press. USA.

www. sutherlandia.org

Seier JV, Mdhuli M, Dhansay MA, Loza J, Laubschner R, Matsabisa G. 2002:

A toxicity study of sutherlandia leaf powder (Sutherlandia microphylla) consumption. South African Ministry of Health Document 2002 [http://www. sahealthinfo.org/traditionalmeds/ cancerbush2.pdf].

Web sites of interest

http://www.sutherlandia.org/--web site for all aspects relevant to Sutherlandia

http://www.parceval.co.za/suth2.htm--a good monograph available at this site

http://www.richters.com--seeds available from this supplier

http://www.bigtreehealth.com/--capsules available from this supplier

http://www.africanbotanicals.com/--a good range of South African medicinal herbs.

http://apps.rhs.org.uk/plantselector/plant?plantid=1889--Royal Horticultural Society

All plant photos taken by the author.

Dr Stuart Glastonbury mmbs BSc(Med) DipWHM

Toowoomba, Queensland, Australia

Email: s.glastonbury@optusnet.com.au
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Title Annotation:Growing and manufacturing
Author:Glastonbury, Stuart
Publication:Australian Journal of Herbal Medicine
Article Type:Report
Geographic Code:8AUST
Date:Jan 1, 2013
Words:1308
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