Bacteria in Blood May Hold the Key to Younger Skin

People go to great lengths to maintain youthful-looking skin with masks, creams and serums. Now, researchers have discovered compounds with anti-aging properties hidden beneath our own skin. The three molecules, produced by a bacterium in the blood, reduced damage and inflammatory responses in human skin cell cultures. These findings, published in the Journal of Natural Products by the American Chemical Society and the American Society of Pharmacognosy, could lead to new treatments for aging skin.

Scientists know little about how bacteria by-products (called metabolites) released into the bloodstream impact human health. One class of metabolites of particular interest are indole compounds because of their anti-aging, anti-inflammatory and antimicrobial properties. In 2015, a blood bacterium that produces indole compounds was discovered, named Paracoccus sanguinis. Chung Sub Kim, Sullim Lee and colleagues were curious about P. sanguinis and investigated its indole-functionalized metabolites. 

“We became interested in P. sanguinis because blood-derived microbes are a relatively uncharted area of research,” says Kim. “Given the unique environment of the bloodstream, we believed that studying individual species like P. sanguinis could reveal previously unknown metabolic function relevant to health and disease.”

The team grew a big batch of P. sanguinis for three days and then extracted the mixture of metabolites the microbes produced. A combination of analytical methods, including spectrometry, isotope labeling and computational analysis, enabled the team to tease out the chemical structure of 12 individual indole metabolites from this mix, including six that had never been identified. 

Next, Kim, Lee and colleagues investigated whether these indole metabolites could mitigate harmful processes that are also associated with aging in human skin. They applied liquid solutions containing each indole to wells with cultured human skin cells. Prior to the experiment, the cells were treated to induce elevated levels of reactive oxygen species, compounds responsible for inflammation and collagen damage. 

Of the 12 indoles the researchers investigated, three, including two newly identified ones, lowered the amounts of harmful reactive oxygen species in the stressed human skin cells compared to untreated cells. The three metabolites also reduced the levels of two inflammatory proteins and a collagen-damaging protein. 

As a result of these initial findings, the researchers say the new indole metabolites are promising candidates for future treatments to counteract skin aging.

Reference: Lee WM, Ahn SY, Lee GS, et al. Discovery and biosynthesis of indole-functionalized metabolites from the human blood bacterium, Paracoccus sanguinis, and their anti-skin aging activity. J Nat Prod. 2025;88(5):1120-1129. doi: 10.1021/acs.jnatprod.4c01354

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