Definition
Gunnera Perpensa Rhizoma consists of the fresh or dried rhizome of Gunnera perpensa L. (Gunneraceae).

Synonyms

Vernacular names
Wilde ramenas, wilde kalbas, rivierpampoen (A), river pumpkin, qobo (S), ipuzi lomlambo (Xh), ughobo, uklenya (Z).

Description

Macroscopical¹
Rhizomatous thinly hairy perennial herb to 1m in height; leaves palmate, tufted, near apex of rhizome, round to reniform with dentate margin, 4-25 × 6-38 cm, on stout petioles 15-75cm long; flowers (Oct-Jan) male, female or bisexual, greenish, sessile, borne in spike-like racemes 2-10cm long; rhizome creeping, to 3cm thick, yellow-fleshy internally. 

Figure1a: fresh rhizome

Figure1b: Live plant

Figure 2: line drawing

Microscopical

Figure 3: microscopical features

Characteristic features are: the light brown cork tissue of the outer bark (5); the thick-walled parenchyma and collenchyma with intercellular spaces (1), staining bright yellow-orange with phloroglucinol/HCl; the many reticulately thickend vessels up to 120µ in diameter (6); the groups of grey-brown cells of the cortex (4); the absence of starch and tanniniferous tissue; the calcium oxalate crystals of the central stele, up to 40µ in diameter (2).

Crude drug
Collected as required or obtained in the marketplace as fresh to semi-dry pieces of rhizome, up to 15cm long and 3cm in diameter, dark brown externally, cream to dark pink internally, texture hard to fleshy, odour faint.

Geographical distribution
Marshes, stream banks and permanent seeps of the Western and Eastern Cape Provinces, Free State Province, KwaZulu/Natal, Mpumalanga, Swaziland, Lesotho; also Zimbabwe, Malawi and East Tropical Africa.

Figure 4: distribution map

Quality standards

Identity tests
Thin layer chromatography on silica gel using as solvent a mixture of toluene:diethyl ether:1.75M acetic acid (1:1:1). Reference compound cineole (0,1% in chloroform). Method according to Appendix 2a.

R_f values of major compounds: 0.04 (pale lilac); 0.12 (pale lilac); 0.30 (grey-mauve); 0.36 (grey-mauve); 0.42 (grey-brown); 0.59 (light purple); cineole: 0,79 (blue-purple)

Figure 5: TLC plate

HPLC on C₁₈ column, method according to Appendix 2b.

Major compounds:

Methanol extract:

Retention times (mins): 2.89; 4.35; 6.12; 11.31; 13.77; 21.08; 25.88

Figure 6: HPLC spectrum

Ethanol (70%) soluble extractive value: not less than 34.81% (range: 34.81-38.18%)

Purity tests

Assay
Not yet available

Major chemical constituents
Little is known of the chemistry of this species. The occurrence of a bitter principle, named celastrin, has been reported ^GR1

Dosage forms
Aqueous infusions and decoctions are taken orally but may also be applied externally as a lotion or wound dressing.

Medicinal uses
Root decoctions are used in traditional gynaecological practice as well as traditional veterinary practice to initiate labour, assist delivery or to expel the placenta. Gunnera perpensa rhizome is a common ingredient of inembe and isihlambezo, preparations used during the last trimester of pregnancy to ensure healthy foetal growth and easy delivery². Decoctions are also taken orally to relieve dysuria, rheumatic pains and dyspepsia, as a stomachic, or for colds. Externally a decoction is used as a wound dressing. Infusions may be taken internally or applied externally to treat psoriasis.  ^{GR1 .}  

Pharmacology/bioactivity
An aqueous decoction of Gunnera perpensa rhizome exhibited direct activity on isolated rat uterine smooth muscle but not on that of the ileum. Response to oxytocin-induced uterine contractions were potentiated by the extract³. Abortifacient activity has been reported, but details are not available⁴.

Water, hexane and 100% ethanol extracts of dried root, assessed for in vitro antibacterial activity against Staphylococus aureus, Klebsiella pneumoniae, Bacillus subtilis and Escherichia coli, were found to be inactive in the concentrations used⁵.

Contraindications
To be established.

Adverse reactions
None reported but investigation necessary.

Precautions
The use of this herb during pregnancy should be undertaken only on the advice of a competent traditional practitioner. Non-pregnant women taking Gunnera perpensa preparations for other indications should be advised of the possibility of abortifacient activity.

Dosage
To be determined.

References

1. Mendes, E.J. (1978). Haloragaceae. Flora Zambesiaca 4: 74-81.
2. Veale, D.J.H., Oliver, D.W., Arangies, N.S. and Furman, K.I. (1992). South African traditional herbal remedies used during pregnancy andchildbirth. Journal of Ethnopharmacology 36: 185-191.
3. Kaido, T.L., Veale, D.J.H., Havlik, I. and Rama, D.B.K. (1997). Preliminary screening of plants used in South Africa as traditional herbal remedies during pregnancy and labour. Journal of Ethnopharmacology 55: 185-191.
4. Jonathan, L.T. (1995). Traditional versus modern medicine: the case for a collaborative approach to primary health care. Journal of Research: Ethnomedicine in Africa: 9-18. National University of Lesotho Occasional Publication 4, Roma, Lesotho.
5. Mc Gaw, L.J., Jager, A.K. and van Staden, J. (2000). Antibacterial, anthelmintic and anti-amoebic activity of South African medicinal plants. Journal of Ethnopharmacology 72(1/2): 247-263.