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TROPOLONE.

Valuable CAS 533-75-5 / SKIN CONDITIONING

Tropolone is a versatile organic compound valued in skincare for its multi-faceted benefits. It acts as a potent antioxidant, offers broad-spectrum antimicrobial protection, alleviates inflammation, and contributes to skin brightening. This ingredient also enhances the stability and longevity of cosmetic formulations.

Preservative Antioxidant Anti-inflammatory Antibacterial Skin Brightening Chelating

Science

Tropolone functions by neutralizing harmful free radicals, thereby protecting the skin from oxidative stress and supporting anti-aging processes. It exhibits anti-inflammatory properties that can effectively soothe irritated skin and diminish redness. Furthermore, tropolone derivatives are known to inhibit tyrosinase, an enzyme crucial for melanin production, which aids in achieving a more even and brighter skin tone. Its inherent bacteriostatic and fungistatic characteristics provide antimicrobial protection, acting as an effective preservative. Additionally, Tropolone serves as a chelating agent, binding to metal ions to safeguard formula integrity and extend shelf life.


Research

Medium confidence
Effective range 0.0001–1%
Optimal

0.05%

Key findings

  1. 01 Clinical observations suggest Tropolone derivatives provide antioxidant activity, effectively utilized in cosmetic and topical pharmaceutical compositions at concentrations ranging from 0.0001% (1 ppm) to 1% (10000 ppm).
  2. 02 Research indicates Tropolone possesses anti-inflammatory capabilities, beneficial for calming irritated skin and reducing erythema. Its derivatives have also been explored for tyrosinase inhibition, implying a role in skin brightening formulations, with a general usage rate in cosmetics typically between 0.01% and 0.1%.

Transparency

Not commonly dusted
Min. effective
0.0001%
Red flag below
0.00005%

Tropolone demonstrates significant efficacy even at remarkably low concentrations, with antioxidant benefits starting from 0.0001% (1 ppm). The typical cosmetic usage ranges from 0.01% to 0.1%, where it provides multiple functional benefits including preservation and anti-inflammatory action. Given its potent activity at these low levels, inclusion at percentages below 0.0001% might suggest 'dusting,' but its general effective range is broad enough to make such practices uncommon.


The Formula

Solubility
Both
Optimal pH 4 – 7
0 7 14

Stability

Tropolone exhibits optimal stability within a pH range of 4.0 to 7.0, although it remains effective across a broader range of 3.0 to 9.0. It tolerates temperatures up to 60°C; however, exposure to higher heat should be avoided. Tropolone is hygroscopic and must be stored in a tightly sealed container, protected from direct sunlight or heat. It is soluble in water (40.9 g/L) and various organic solvents such as ethanol; for maximum aqueous solubility, pre-dissolving in ethanol before dilution is recommended.

Conflicts

  • High heat (above 60°C)
  • Direct contact with strong acids or bases (particularly relevant for the raw material)

Safety

CIR Status
Not reviewed
Max tested
1%
Sensitization risk Moderate

While the raw chemical form of Tropolone carries GHS hazard classifications indicating corrosivity and potential for allergic skin reactions (H314, H317), in carefully formulated cosmetic products at low concentrations (typically 0.01-0.1%, up to 1% for antioxidant effect), it is widely considered safe. SkinSAFE products containing Tropolone are frequently rated 'Teen SAFE', 'Baby SAFE', and 'Irritant Free'. Currently, no specific safety assessments by the CIR or SCCS have been published, and its FDA status for cosmetic use remains unknown.


Your Skin

Yes Normal
No Dry
No Oily
Yes Sensitive
Irritancy Low
Comedogenicity Unknown

Our Assessment

Valuable

Tropolone is a valuable multi-functional ingredient, offering significant antioxidant, anti-inflammatory, antimicrobial, and brightening benefits, while also enhancing formula stability and being suitable for sensitive skin in appropriate concentrations.


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