Pelargonium species contribute significantly to the health care of a large population in the Southern African region, as part of a long-standing medical system intimately linked to traditional healing practices. Most notably, extracts of the roots of P. sidoides have commonly been applied for the treatment of dysentery and diarrhoea but only occasionally for respiratory complaints. Clinical trials have shown that a modern aqueous-ethanolic formulation of P. sidoides extracts (EPs^® 7630) is an efficacious treatment for disorders of the respiratory tract, for example bronchitis and sinusitis. It should be noted that EPs^® 7630 is the most widely investigated extract and therefore is the focus of this review. In order to provide a rationale for its therapeutic activity extracts have been evaluated for antibacterial activity and for their effects on non-specific immune functions. Only moderate direct antibacterial capabilities against a spectrum of bacteria, including Mycobacteria strains, have been noted. In contrast, a large body of in vitro studies has provided convincing evidence for an anti-infective principle associated with activation of the non-specific immune system. Interestingly, significant inhibition of interaction between bacteria and host cells, a key to the pathogenesis of respiratory tract infections, has emerged from recent studies. In addition, antiviral effects have been demonstrated, including inhibition of the replication of respiratory viruses and the enzymes haemagglutinin and neuraminidase. Besides, an increase of cilliary beat frequency of respiratory cells may contribute to the beneficial effects of P. sidoides extracts. This example provides a compelling argument for continuing the exploration of Nature and traditional medical systems as a source of therapeutically useful herbal medicines.

A series of hydrolysable tannins and related compounds was evaluated for antifungal activities against filamentous fungi ( Epidermophyton floccosum; Microsporum canis; Microsporum gypseum: Trichophyton mentagrophytes; Trichophyton rubrum; Trichophyton tonsurans; Trichophyton terrestre; Penicillium italicum; Aspergillus fumigatus; Mucor racemosus; Rhizopus nigricans) and opportunistic yeasts ( Candida albicans; Candida glabrata; Candidata krusei; Cryptococcus neoformans), using the agar dilution method. While all samples had no activity against the filamentous fungi in concentrations of 1.1 -5.9 μм (1000 [μg/ml), the phenolic compounds displayed significant potencies against all the opportunistic yeasts tested but C. albicans, with minimum inhibitory concentrations ranging from 0.02 to 0.1 μм ( 16 - 125 (μg/ml). Although the presence of galloyl groups in flavonoids did not necessarily produce activity, this structural element, an HHDP moiety or its oxidatively modified entity proved to be an important structural feature of hydrolysable tannins. Comparison of dilution methods provided strong evidence of dependence of MIC values on the test method. Employing the microdilution broth method, the ellagitannin corilagin (MIC 0.8 nм) was found to be similarly potentially active as amphotericin B (MIC 0.5 nм) and sertaconazole (MIC 0.9 nм) against Candida glabrata strains. The order of effectiveness observed being 64- and 4 -8-fold increased for corilagin and the reference compounds respectively, when compared with that of the agar dilution test.