Potential medicinal value of some South African seaweeds

Eleven macroalgae were collected from the KwaZulu-Natal coast and nineteen species from the cooler Western Cape coast in March and April 2000. Ethanolic and aqueous extracts were made and tested for biological activity in the Cox-1 anti-inflammatory assay, in a nematode mortality bioassay for anthelminthic activity, an IC50 anticancer assay and a MIC antimicrobial assay. The ethanolic extracts were very active in the Cox-1 anti-inflammatory assay for almost all of the species tested. The aqueous extracts were not active. No anthelminthic mortality was detected in extracts from any of the species tested. Many of the extracts had cytotoxic activity against three cancer cell lines tested, with those from representative species of the Chlorophyta and Rhodophyta being the most effective. The extracts had much lower cytotoxic activity when tested on normal mouse fibroblasts (NIH3T3). Extracts from only a few species had antimicrobial activity with those of the Chlorophyta tested being the most effective against both the Gram-positive and Gram-negative bacteria

The distribution of algae epiphytic on pneumatophores of the mangrove, Avicennia marina, at different salinities in the Kosi System

Samples of algae epiphytic on the pneumatophores of Avicennia marina (Forssk.) Vierh. were collected at different seasons of the year. The distribution of this mangrove, which extends from the mouth of the estuary to Wankute island, approximately 6.5km upstream, covers a salinity range from 35‰ to 7‰ at its upper limits, and includes the Ukhalwe inlet in which the surface water of the upper reaches is 0‰. Thirty-six species of epiphytic algae were collected across this distribution range, of which there were 11 rhodophycean, 17 cyanophycean (cyanobacteria), 7 chlorophycean and 1 phaeophycean. Most of the red algae were restricted to the high (>25‰) salinity areas, while the blue-green algae generally appeared to have a wider salinity and exposure tolerance. Six algal species were found to have a distribution covering the entire salinity range, 10 species were recorded in waters ranging from 35‰ to 7‰, 16 and 2 species were limited to high (>25‰) and lower (5-18‰) salinity areas, respectively, while one species occurred only in freshwater. The ecological implications of these results are discussed. The need for additional collections from localities to the north is stressed to establish the affinities of this community with those in more tropical areas