Review‘Buchu’ – Agathosma betulina and Agathosma crenulata (Rutaceae): A review
Introduction
The Cape region of South Africa has veldt-types with arguably the richest composition of indigenous aromatic plant species in the whole of South Africa. It is in this epicenter of essential oil-bearing plants, that the genus Agathosma and its close taxonomic allies (e.g. Diosma, Coleonema, Acmadenia) reside. These Rutaceous shrubs are typical of the fynbos (vegetation found in the western Cape Province of South Africa) and are particularly abundant in the mountainous areas in the Cape (Van Wyk and Gericke, 2000). The Khoi-San used the word ‘Buchu’ for any fragrant plant that could be dried and powdered, so in a historic sense this name does not designate a single species. Nowadays it is generally accepted that ‘Buchu’ refers to Agathosma betulina and Agathosma crenulata. Agathosma species are perennial shrubs with woody branches and small, flat, gland-dotted leaves with a rue-like smell. Of the 150 Agathosma species indigenous to South Africa, Agathosma betulina (round-leaf buchu; ‘bergboegoe’; short buchu) and Agathosma crenulata (oval-leaf buchu; ‘anysboegoe’; long-leaf buchu) are probably one of the best known South African herbs used both locally and internationally for medicinal purposes. Despite the long and established history of traditional use, the unique sulfur-containing compounds in the volatile fraction with desirable organoleptic properties have diverted attention from the medicinal uses to various applications in the fragrance and flavour industry. Recent studies, some of which are highlighted here, have been undertaken to document the pharmacological properties of ‘Buchu’ which confirms the several health benefits ascribed to Agathosma betulina and Agathosma crenulata.
Section snippets
Botanical aspects
In a taxonomic appraisal of commercially important Agathosma species (previously named Barosma), Spreeth (1976) includes Agathosma betulina, Agathosma crenulata and Agathosma serratalifolia in his treatment. The latter species is no longer of commercial importance and is not further considered in this review.
Agathosma betulina (Bergius) Pillans is a resprouting, broad-leaved, fragrant shrub that grows to a height of 2 m (Fig. 1). The leaves are of a pale green colour, 20 mm long, leathery and
Traditional and modern day uses
‘Buchu’ is an important part of the Khoi-San culture and is still used in the Cape as a general tonic and medicine throughout South Africa. The indigenous people first introduced ‘Buchu’ in the 1650s as a medicinal plant to the European settlers in the Cape. The use of the plant subsequently spread to Europe and America where it was extensively used as a medicine. Some of the traditional uses of Agathosma include: as an antispasmodic; an antipyretic; a liniment; a cough remedy, as well as for
Phytochemistry
Campbell et al. (1986) investigated 24 species from the genera Agathosma, Diosma and Empleureum (tribe Diosmeae) for coumarins. Nine simple coumarins were isolated. The aerial parts of 42 taxa of the genera Agathosma, Coleonema, Diosma, Empleureum and Phyllosma (tribe Diosmeae) were screened in a study by Campbell et al. (1987) for alkaloids. Positive results were obtained for five Agathosma species and the compounds halfordamine and skimmianine were identified. Although various Agathosmas were
Antimicrobial activity
The antimicrobial activity of the hydrodistilled essential oils and methanol:dichloromethane (1:1) extracts of the two species was evaluated using the minimum inhibitory concentration (MIC) assay as determined by a micro-titre plate dilution method in studies performed by Moolla et al. (2007) and Viljoen et al. (2006). Both the extracts and the essential oils were active against the four pathogens tested (i.e. Staphylococcus aureus ATCC 12600, Bacillus cereus ATCC 11778, Klebsiella pneumoniae
Conclusions
‘Buchu’ enjoys a rich history as a panacea to treat a range of conditions and undoubtedly ranks amongst South Africa’s most important medicinal plants and export products. Despite this established use, the chemistry and biological activity remains poorly explored. Although research in the pharmaceutical domain has been performed on ‘Buchu’, these studies are mostly of an in vitro nature and few studies have been completed to verify the uses for which ‘Buchu’ is reported to have been used
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