ROCHESTER, Minn. (AP) — The quest for eternal youth never gets old.

By extension, companies making progress on developing anti-aging treatments always have been very popular with deep-pocketed investors.

The latest focus on making people healthier as they grow old by combating age-related maladies is attracting a lot of attention. Unity Biotechnology, a San Francisco-based biotechnology firm co-founded by Mayo Clinic molecular biologist Dr. Jan van Deursen, is drawing in big investors such as Amazon's Jeff Bezos as the research advances.

Unity, which was founded in 2011, announced it took in a jaw-dropping $116 million in Series B financing last week. Investors included Bezos and Mayo Clinic. Mayo Clinic also invested in the company's first round of financing. However, clinic officials decline to say how much it has invested in Unity to date, the Post Bulletin reported (http://bit.ly/2eoCRTb ).

Unity, building on research by van Deursen and others, is working on "scrubbing out" the build-up of old, so-called "zombie" cells that have undergone a natural process called senescence. These cells clog up healthy systems, break down tissue and attract immune cells causing inflammation. A lot of aging-related problems are attributed to these cells.

Dr. James Kirkland, a Mayo Clinic scientist working with van Deursen, was quoted earlier this year, explaining the potential of the research.

"By attacking these cells and what they produce, one day we may be able to break the link between aging mechanisms and predispositions to diseases like heart disease, stroke, cancers and dementia. There is potential for a fundamental change in the way we provide treatment for chronic diseases in older people," he was quoted as saying.

Van Deursen is encouraged by the research so far.

"This has been a long journey, and we're at the point now where we can start making medicines to achieve in humans what we've achieved in mice," he said in a news article in February.

Unity is not the only firm working on anti-aging treatments. Other competitors in the field are SIWA Therapeutics and Oisin Biotechnologies.

However, Mayo Clinic characterizes Unity as working on the most promising approach.

"While there have been many exciting discoveries relating to the biology of aging, cellular senescence is the most 'druggable' mechanism we know of right now. Unity's science holds promise for treating a wide range of diseases and lengthening human health span, and the company's management team has the right experience to bring these therapies into the clinical area," said Mayo Clinic's Duska Anastasijevic. "It is very well aligned with the research done at Mayo Clinic under the auspices of the Robert and Arlene Kogod Center on Aging."

In February, Unity co-founder and current president Nathaniel David explained how a serial biotech entrepreneur such as himself was drawn into this project. In 2011, he saw an article by van Deursen about his research. Within three days, David had an appointment with the Mayo Clinic scientist.

"I said, 'This is awesome. Let's start a company,'" David was quoted as saying earlier this year.

While Unity is attracting a lot of attention and money, it's years away from bringing a product to market. However, it is working toward a series of clinical trials that, if positive, eventually could result in a product.