Padina australis is a member of the brown algae group (Ochrophytas) which is characterized by being flattened, with a thin structure and a slightly rigid texture. The stem of this species, which takes the shape of a fan, is yellowish / brown in color with whitish areas that are typical of light deposits of calcium carbonate on them. These whitish bands adopt a concentric conformation, thus generating the appearance of the growth rings present in the trunks of the trees when they are cut horizontally, but do not reflect the grothw in the algae. It is an annual species, which after the season, its stalk will detach from the seabed, for the next season to grow again from the rhizoids left attached to the substrate the previous season.
The distribution of Padina australis is extensive, being able to find it throughout the length and breadth of the Indian and Pacific oceans waters. It grows attached to rocks, in the gravel or on dead coral areas in the middle intertidal zone of moderately exposed coasts, where it can reach 6-18 cm high and 5-15 cm in diameter.
As with many other algae, various compounds with attractive properties can be isolated from Padina australis. Some of these compounds have a remarkable capacity to act as antioxidant molecules, having demonstrated potential in their use for the treatment of neurodegenerative diseases. Fucoidan, a viscous substance obtained from Padina australis, among other species, has several medicinal properties that make them attractive. It is capable of inhibiting the formation of new blood vessels (angiogenesis) and of triggering the death of tumor cells (apoptosis), so its use for the field of cancer is being investigated. Fucoidan also possesses antioxidant capabilities and is able to stimulate intestinal immune activity. Besides biomedicinal uses, Padina australis has been used also to monitor heavy metal contamination of the waters.
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