''Lessonia nigrescens'', the grey weed or giant grey weed, is a South American kelp species in the genus '' Lessonia''. There is at least two populations of the seaweed, marked by the difference in phenolic content. There is a subtidal population with higher phenol content and an intertidal population with a lighter phenol content. The difference in the phenolic content can be explained by the herbivory selection pressure due to the sea snail ''

Tegula tridentata ''Tegula tridentata'' is a species of sea snail, a marine gastropod mollusk in the family Tegulidae.Bouchet, P. (2013). Tegula tridentata (Potiez & Michaud, 1838). Accessed through: World Register of Marine Species at http://www.marinespecies.org ...

''. UV treatment induces the production of

phlorotannin Phlorotannins are a type of tannins found in brown algae such as kelps and rockweeds or sargassacean species, and in a lower amount also in some red algae. Contrary to hydrolysable or condensed tannins, these compounds are oligomers of phlorogl ...

s that accumulate in

physode Phlorotannins are a type of tannins found in brown algae such as kelps and rockweeds or sargassacean species, and in a lower amount also in some red algae. Contrary to hydrolysable or condensed tannins, these compounds are oligomers of phlorogl ...

s. This weed contains the phytosterol

saringosterol Saringosterol is an isolate of ''Lessonia nigrescens'' that has activity against ''Mycobacterium tuberculosis''. References

Sterols {{steroid-stub ...

that shows an inhibitory effect on ''

Mycobacterium tuberculosis ''Mycobacterium tuberculosis'' (M. tb) is a species of pathogenic bacteria in the family Mycobacteriaceae and the causative agent of tuberculosis. First discovered in 1882 by Robert Koch, ''M. tuberculosis'' has an unusual, waxy coating on its c ...

'' growth.Inhibition of Mycobacterium tuberculosis growth by saringosterol from Lessonia nigrescens. Wächter Gerald A, Franzblau Scott G, Montenegro Gloria, Hoffmann Joseph J, Maiese William M and Timmermann Barbara N, Journal of Natural Products, 2001, volume 64, number 11, pages 1463-1464,

References

External links

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algaebase.org
Species described in 1826 nigrescens {{Phaeophyceae-stub