In vitro biological activity and essential oil composition of four indigenous South African Helichrysum species

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Abstract

Helichrysum species are used widely to treat various medical conditions. In this study, the anti-microbial, anti-oxidant (DPPH assay) and anti-inflammatory activity (5-lipoxygenase assay) of Helichrysum dasyanthum, Helichrysum felinum, Helichrysum excisum and Helichrysum petiolare were investigated. The essential oil compositions of these species were determined. The acetone and methanol extracts as well as the essential oils exhibited activity against Gram-positive bacteria, while both the methanol and acetone extracts of all four species were active in the anti-oxidant assay. The essential oils, on the other hand, displayed activity in the 5-lipoxygenase assay, which was used as an indication of anti-inflammatory activity. Two extracts exhibited promising activity in the anti-microbial assay, the acetone extract of Helichrysum dasyanthum with a MIC value of 15.63 μg/ml and the methanol extract of Helichrysum excisum with a MIC value of 62.5 μg/ml. The acetone extract of Helichrysum dasyanthum was the most active free radical scavenger in the DPPH assay (IC50 of 9.53 μg/ml) while values for the anti-inflammatory activity of the essential oils ranged between 25 and 32 μg/ml. The essential oil compositions of three species (Helichrysum dasyanthum, Helichrysum excisum and Helichrysum petiolare) were dominated by the presence of monoterpenes such as α-pinene, 1,8-cineole and p-cymene. In the oil of Helichrysum felinum, monoterpenes were largely absent. Its profile consisted of a variety of sesquiterpenes in low concentrations with β-caryophyllene dominating.

Introduction

Species from the genus Helichrysum (Asteraceae) are used in Europe (Czinner et al., 2000) and Africa (Hutchings et al., 1996, Hutchings and Van Staden, 1994, Van Wyk et al., 1997, Watt and Breyer-Brandwijk, 1962) in the treatment of various medical conditions. It is a very large genus consisting of approximately 500 species of which 245 are indigenous to South Africa (Hilliard, 1983). Helichrysum species are traditionally used in the treatment of wounds, infections and respiratory conditions (Hutchings et al., 1996, Van Wyk et al., 1997, Watt and Breyer-Brandwijk, 1962). Infection often leads to inflammation, and free radicals are released from phagocyte cells during the inflammatory process (Folkerts et al., 2001). Since many respiratory conditions and skin ailments such as atopic dermatitis (Tsukahara et al., 2003) are associated with inflammation (and hence release of free radicals) as well as infection, the presence of anti-inflammatory, anti-oxidant and anti-microbial agents could explain the effectiveness of plants from this genus in the treatment of these conditions.

The extracts as well as the essential oils from Helichrysum species have exhibited promising biological activities in many in vitro assays which include anti-oxidant (Czinner et al., 2000), anti-microbial (Meyer and Afolayan, 1995) and anti-inflammatory activity (Jäger et al., 1996). This genus has furthermore been a source of many fascinating (and bioactive) compounds (Bremner and Meyer, 2000, Dekker et al., 1983, Mathekga et al., 2000, Tomás-Barberán et al., 1990, Tomás-Lorente et al., 1989). Even though this large genus has been extensively investigated, the biological activity and/or chemical composition for many species still remain unrecorded. This is especially true for the essential oil composition of indigenous South African species. Furthermore, since Helichrysum species are distributed widely throughout South Africa, their medicinal use often depends on local availability rather than preference for a particular species (Van Wyk et al., 1997). In this study, the biological activity of four indigenous Helichrysum species were investigated. This was done with regard to their anti-microbial, anti-oxidant and anti-inflammatory activity as well as their essential oil composition as part of a continuing project to explore the phytochemistry and medicinal potential of South African flora.

Section snippets

Plant material

Plant material of the three species Helichrysum dasyanthum (Willd.) Sweet, Helichrysum excisum (Thunb.) Less, and Helichrysum felinum Less were collected on Robinson's Pass in the Southern Cape. The sample of Helichrysum petiolare Hilliard and Burtt was obtained from the National Botanical Institute in Pretoria. The material was air-dried and ground. Voucher specimens were prepared and deposited at the Department of Pharmacy and Pharmacology, University of the Witwatersrand.

Preparation of extracts

Extracts were

Results and discussion

Since anti-microbial activity was observed almost solely against Gram-positive bacteria, correlating with results from other studies (Mathekga et al., 2000, Meyer and Afolayan, 1995), only these results (Table 1) are supplied. The results indicate that high activity in the disc diffusion assay does not necessarily correlate to low MIC values in the micro-titre plate assay. The disc diffusion assay was only used as an indication of anti-microbial activity since the amount of extract or oil that

Acknowledgements

We are indebted to the National Research Foundation (Indigenous Knowledge Systems) and the University of the Witwatersrand Research Committee for financial support. We acknowledge the help of Mr Jan Vlok in the identification of plant material.

References (25)

  • V. Roussis et al.

    Volatile constituents of four Helichrysum species growing in Greece

    Biochemical Systematics and Ecology

    (2000)
  • A. Sala et al.

    Assessment of the anti-inflammatory activity and free radical scavenger activity of tiliroside

    European Journal of Pharmacology

    (2003)
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