Seaweed compounds show HIV efficacy
new compounds with pharmaceutical potential, some of which showed
the potential to kill cancer cells, bacteria and even the HIV
virus.
The research also discovered two of them exhibited anti-bacterial activity towards antibiotic-resistant Staphylococcus aureus at significant concentrations. If these natural resources become marketable drugs it could prove to be the most effective weapon for these killer pathogens.
The compound that was isolated in the greatest abundance - named bromophycolide A by the researchers - killed human tumour cells by inducing programmed cell death (apoptosis), a mechanism that is promising for development of new anti-cancer drugs.
The source of these new molecular structures is a red seaweed (Callophycus serratus) collected from four Fijian sites.
Among the sites, researchers found variations in the molecular structures produced by the species.
"Marine organisms make molecules for their own purposes that we might co-opt for our own use as pharmaceutical agents," said Julia Kubanek, the lead author on the paper.
"The organisms' purposes include defence against predators, the ability to fight diseases, and the production of chemical cues, such as those used for sex recognition. The next step is to discover how these compounds work and then to study them in a more complex model system."
In the lab, researchers extracted these organisms using mixtures of organic liquids, which opened up the cells and dissolved the natural products.
The organic liquids were then removed from the extract by evaporation, and small quantities of each extract were tested against a battery of pharmaceutical drug targets, including malarial parasite, tuberculosis-causing bacteria, and several cancers.
Typically, these tests involve exposing live, disease-causing cells - parasites, bacteria or cancer cells - to an extract and then assessing cell death compared to cells that were not exposed to extracts.
Scientists from the Georgia Institute of Technology then prioritised further study of extracts that had strong effects on these disease-causing cells.
"These molecular structures are curious in the way carbon atoms are attached," said Kubanek
"It's very unusual. They represent a new category of organic molecules. It's exciting as a biochemist to observe that living organisms have evolved the ability to synthesize such unique and exotic structures compared to other molecules typically produced by seaweeds."
The US pharmaceutical company Bristol Myers Squibb is collaborating with Georgia Tech researchers to determine how some of these 10 compounds kill cancer cells.
Meanwhile, Georgia Tech has filed a provisional patent to protect the discovery of these structures and small variations of them.
The study commented that much research is left to do before any of these compounds could be used to formulate a drug available on the market.
It typically takes at least a decade from the discovery of a compound to the marketing of a new drug.
The findings on three of these compounds called diterpene-benzoate natural products are reported in the Oct. 12 online issue of the American Chemical Society journal Organic Letters.
