Norway Spruce Resin Extract Fights Acne Bacteria and Inflammation at 30% Concentration, Study Finds

Picea abies, the Norway spruce, produces a resin that trees generate when their bark is wounded. A team led by Simone Parrotta and colleagues, publishing in the International Journal of Cosmetic Science, extracted that resin and tested it as a treatment for mild acne, reporting results from chemistry through a 28-day in-use trial.

The extract's activity turned out to hinge on concentration. Researchers determined a minimum inhibitory concentration of 30% against Cutibacterium acnes, the bacterium implicated in acne lesions. At that same 30% level, the raw extract delivered a reduction of more than 4.9 log10 in bacterial counts after 8 hours. Once formulated into a cream at 30%, the reduction measured 4.03 log10 over the same window, a smaller but still substantial effect once the extract moved from a test tube into a topical base.

Gas chromatography-mass spectrometry identified what's actually driving that activity: p-coumaric acid, several resin acids, and three lignans, pinoresinol, isolariciresinol, and secoisolariciresinol. Lignans are plant compounds more commonly discussed in the context of flaxseed or sesame, so their presence in a conifer resin extract marks this as an ingredient profile distinct from typical botanical anti-acne actives like tea tree oil or salicylic acid.

Beyond killing bacteria, the cream changed inflammatory signaling in lab-grown human skin cells. In keratinocytes stimulated with LPS to mimic an inflammatory trigger, the cream reduced IL-1α by 14 to 17%, IL-6 by 22 to 39%, and IL-8 by 16 to 26%. In dermal fibroblasts, cellular protein synthesis rose 35 to 50% within 24 to 48 hours, a signal the authors link to early tissue repair rather than confirmed collagen production. Docking simulations against AlphaFold2-generated models of IKKβ, JNK1, NF-κB, and PPARγ suggested the lignans and p-coumaric acid could bind these inflammation-related targets. The authors frame this as a hypothesis for future mechanistic work, not proof of how the extract acts in skin.

Safety testing followed ISO 10993-5 agar diffusion for cytotoxicity and a 48-hour human patch test; neither turned up irritation. The clinical portion was small and open-label: 31 adults with mild facial acne used the 30% cream for 28 days with no control group or blinding. Total lesion counts fell 26.8%, papules fell 52.1%, and comedones fell 17.6%, all reaching statistical significance in the paper's analysis. Acceptability landed at 87% favorable, with no intolerance reported.

The authors are explicit about the limits of that last result. An open-label study with no vehicle comparison can't separate a real drug effect from expectation, routine skincare habits, or acne's tendency to fluctuate on its own. The paper's own conclusion calls for randomized, vehicle-controlled trials with adequate statistical power before any claim about papule or comedone reduction can stand on its own. For now, what the data support is narrower: a 30% Picea abies resin extract, built from lignans and resin acids unique to spruce, inhibits C. acnes in a cream base and quiets several inflammatory cytokines in cultured skin cells.