Preliminary screening of some traditional zulu medicinal plants for anti-inflammatory and anti-microbial activities

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Abstract

Aqueous and methanolic extracts from different parts of nine traditional Zulu medicinal plants, of the Vitaceae from KwaZulu-Natal, South Africa were evaluated for therapeutic potential as anti-inflammatory and anti-microbial agents. Of the twenty-nine crude extracts assayed for prostaglandin synthesis inhibitors, only five methanolic extracts of Cyphostemma natalitium-root, Rhoicissus digitata-leaf, R. rhomboidea-root, R. tomentosa-leaf/stem and R. tridentata-root showed significant inhibition of cyclo-oxygenase (COX-1). The extracts of R. digitata-leaf and of R. rhomboidea-root exhibited the highest inhibition of prostaglandin synthesis with 53 and 56%, respectively. The results suggest that Rhoicissus digitata leaves and of Rhoicissus rhomboidea roots may have the potential to be used as anti-inflammatory agents. All the screened plant extracts showed some degrees of anti-microbial activity against Gram-positive and Gram-negative microorganisms. The methanolic extracts of C. natalitium-stem and root, R. rhomboidea-root, and R. tomentosa-leaf/stem, showed different anti-microbial activities against almost all micro-organisms tested. Generally, these plant extracts inhibited the Gram-positive micro-organisms more than the Gram-negative ones. Several plant extracts inhibited the growth of Candida albicans while only one plant extract showed inhibitory activity against Saccharomyces cerevisiae. All the plant extracts which demonstrated good anti-inflammatory activities also showed better inhibitory activity against Candida albicans.

Introduction

South Africa has an abundance of medicinal plants, used in the traditional treatment of various diseases on an empirical basis (Hutchings and van Staden, 1994, Hutchings et al., 1996, Jäger et al., 1996, Salie et al., 1996, McGaw et al., 1997). Zulu medicinal plants are traded and used all over southern Africa. Scientific investigation and information of the therapeutic potential of the plant material is limited. With the possibility of traditional medical practitioners being integrated into the state health delivery system, there is an urgent need to systematically evaluate plants used in Zulu traditional medicine. Such research could also lead to new drug discovery or advance the use of indigenous herbal medicines for orthodox treatment.

Species from the Vitaceae are widely used by traditional healers in South Africa to ensure safe delivery during pregnancy (Hutchings et al., 1996; Table 1). Rhoicissus tridentata is used to feed children when mothers are not home (Tyiso and Bhat, 1998). Cissus quadrangularis is used to treat patients with burns, gastrointestinal complaints, backache, body-and febrile pain, swellings and malaria. The above medicinal plants along with Cyphostemma natalitium from the same family are also used to treat cancer patients (Hutchings et al., 1996, Neuwinger, 1996). Resveratrol derived from Vitis vinifera which also belongs to the Vitaceae possesses anti-inflammatory and anti-mutagenous activities and is a potential cancer chemopreventive agent (Jang et al., 1997).

Opoku et al. (1999) demonstrated that several aqueous extracts from Zulu medicinal plants of the Vitaceae showed anti-proliferative activities: up to 97% inhibition in vitro against HepG2 cells. Since these medicinal plants are also used to treat burns, swelling and malaria, one can expect that they might possess anti-microbial and anti-inflammatory activities as well. The search for antimicrobial and anti-inflammatory agents is largely concentrated on lower plants, fungi and bacteria (Fabry et al., 1998). Less research focuses on higher plants, although, plant compounds such as berberine, emetine, quinine, and sanguinarine have specialised uses (Van Wyk et al., 1997).

This paper reports on preliminary screening for the anti-inflammatory and anti-microbial activities of nine plant species from three different genera of the Vitaceae.

Section snippets

Plant material

All plant material were collected during February and March 1998. The freshly collected plant parts of Cissus quandrangularis L., Cyphostemma flaviflorum (Sprague) Descoings, Cyphostemma lanigerum (Harv.) Descoings ex Wild and Drum, Cyphostemma natalitium (Szyszyl.) J.V.D. Merwe, Cyphostemma sp., Rhoicissus digitata (L.F.) Gilg and Brandt, Rhoicissus rhomboidea (E. Mey. ex Harv.) Planch, Rhoicissus tomentosa (Lam.) Wild and Drum, Rhoicissus tridentata (L.F.) Wild and Drum, and Rhoicissus

Results and discussion

Nine plant species from three different genera of the Vitaceae were selected because of usage in medicinal treatments in South Africa (Table 1). Successful isolation of botanical compounds from plant material is largely dependent on the type of solvent used in the extraction procedure. The traditional healers use primarily water as the solvent. We found that in this study the plant extracts by methanol provide more consistent anti-microbial activity compared to those extracted by other

Acknowledgements

Funding for this project was provided by University of Zululand Research Fund, National Research Foundation and University of Natal Research Fund. Mr van der Linde from Owen Sithole Agricultural College and Mr Wiggly from the Twinstream Project provided some plant material.

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