The legal proceedings began in April when Mars filed a lawsuit against the Spanish group for infringing patents on extracts the confectionary brand giant has commercialized under its Cocoapro trademark.
Natraceutical markets its cocoa polyphenols under the Cocoanox brand.
Initially, the suit involved two patents, but Mars then added two further patents to the proceedings.
The case is an example of the intellectual property feuds that take place relatively frequently in the nutraceutical industry as companies with intersecting interests find their intellectual property gets too close for comfort.
Approximately one third of Natraceutical's entire ingredients sales are to the US.
Though Mars had initially requested Natraceutical discontinue sales in the US, the Spanish firm indicates it has no intention of doing so.
"We continued selling and we have a lot of projects going on," CEO Jose Vicente Pons Andreu told NutraIngredients-USA.com.
According to Pons Andreu, Cocoanox has generated interest from leading international chocolate companies.
In August, Natraceutical Group proclaimed what it called its first victory in defending the case, when Mars withdrew its request for a preliminary injunction.
This means Natraceutical can continue unrestricted marketing of Cocaonox products in the US throughout the legal proceedings.
Mars did not respond to NutraIngredients-USA's interview request in time for publication of this article.
The patents it seeks to protect include US Patents 6.790.966, 6.312.753, 6.015.913, 6.372.267, 6.737.088, 6.777.005 and 6.905.715.
Natraceutical claims it is not infringing these and furthermore that they are invalid for a variety of reason and therefore unenforceable.
Natraceutical filed the claim on Monday and indicated it has not yet received a response from Mars.
The Spanish biotechnology company said it has a patent surrounding its Cocoanox ingredient, but this is not being contested.
"Our patent is not being challenged - it is valid," said Pons Andreu.
"They [Mars] say we infringed their patent."
Mars has developed ways to measure and characterize polyphenol content in foods, as well as post-harvesting and processing technologies to help maximize the antioxidants available in a variety of formats.
However, Natraceutical claims Mars' actions, with regards to its patents, have violated US antitrust laws.
"Natraceutical Group has devoted substantial resources to its achievements in research and development of nutritional ingredients and functional foods, such as CocoanOX, that can benefit consumers around the world as well as in the US," said Pons Andreu.
"While Natraceutical Group respects the valid intellectual property rights of its competitors, we must protect the interests of Natraceutical Group shareholders and our customers."