Biodegradable Croconic Acid Salts for Photostable UV-A Protection

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Solution Overview

Problem

Existing UV filters in sunscreens and cosmetics are persistent and non-biodegradable, leading to environmental concerns and inadequate protection against UV-A radiation, which contributes to skin cancer and aging.

Innovation Solution

Development of biodegradable croconic acid salts that absorb UV-A radiation effectively, remain dissolved in aqueous solutions, and provide photostability, suitable for use in cosmetic and pharmaceutical compositions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional UV filters are used to provide UV protection, then UV absorption efficacy is improved, but environmental persistence and bioaccumulation worsen

Engineering Contradiction:
ImproveUV absorption efficacyVSAvoidenvironmental persistence and bioaccumulation
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the chemical structure parameter of UV filters by introducing biodegradable functional groups (ester groups, amide groups) while maintaining UV absorption capabilities. This structural modification enables the filters to be broken down by microorganisms into harmless substances like carbon dioxide and water, resolving the contradiction between effectiveness and environmental persistence

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates composite UV filter molecules that combine the UV-absorbing croconic acid core with biodegradable side chains containing ester or amide groups. This composite structure maintains the parent compound's UV protection efficacy while adding environmental degradability, thus resolving the contradiction between reliability and harmful environmental factors

Inventive Principle:
Principle #40Composite materials

2Object-generated harmful factors

If biodegradable UV filters are used to reduce environmental impact, then environmental compatibility is improved, but UV-A protection capability worsens

Engineering Contradiction:
Improveenvironmental compatibilityVSAvoidUV-A protection capability
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent modifies the molecular parameters of biodegradable UV filters by incorporating electron-donating or electron-withdrawing groups at specific positions of the croconic acid core. These parameter changes shift the absorption spectrum into the UV-A range (320-400 nm) while preserving biodegradability, thus resolving the contradiction between environmental compatibility and UV-A protection capability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent designs UV filter molecules that simultaneously achieve multiple functions: UV-A absorption, biodegradability, and skin compatibility. The croconic acid derivatives serve as universal building blocks that can be functionalized to meet all three requirements, resolving the contradiction between environmental friendliness and protective efficacy

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If croconic acid salts are used as UV-A absorbers, then UV-A absorption and biodegradability are improved, but photostability worsens

Engineering Contradiction:
ImproveUV-A absorption and biodegradabilityVSAvoidphotostability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent introduces stabilizing substituents as intermediary groups that protect the photo-sensitive croconic acid core from degradation. These substituents act as mediators that absorb excess energy or prevent reactive oxygen species formation during UV exposure, thereby improving photostability while maintaining UV-A absorption and biodegradability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent incorporates photoprotective groups in advance that prevent photo-degradation before it occurs. These pre-installed protective groups cushion the croconic acid core against UV-induced damage, ensuring long-term photostability while preserving the desired UV-A absorption and biodegradability properties

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

4Ease of manufacture

If water-soluble croconic acid salts are used in cosmetic compositions, then ease of incorporation is improved, but crystallization upon water evaporation worsens

Engineering Contradiction:
Improveease of incorporationVSAvoidcrystallization behavior
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The patent changes the solubility parameters of croconic acid salts by introducing hydrophilic side chains or modifying the counterion. These parameter changes increase water solubility for easy incorporation while simultaneously adjusting the crystallization tendency by modifying molecular packing properties, thus resolving the contradiction between ease of manufacture and composition stability

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The croconic acid salts offer effective UV-A protection, ensuring biodegradability and photostability, addressing environmental concerns while providing broad-spectrum UV protection.

Implementation Method 1

Croconic acid was found to be an excellent UV-A absorber

Methodology Applied
Scientific EffectUV absorption: Absorption (EM radiation)

Implementation Method 2

After applying cosmetic or pharmaceutical compositions (e.g. an emulsion) to the skin, water start to evaporate

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

croconic acid salts are known to be photo-instable, i.e. are known undergoing photooxidation

Methodology Applied
Scientific EffectPhotooxidation: Photo-oxidation

Data Source

PatentEP4167938B1Biodegradable UV absorbers
Publication Date: 2025.08.27 BASF SE
  • EP4167938B1 patent drawingFigure 1A~1B
  • EP4167938B1 patent drawingFigure 2~3
  • EP4167938B1 patent drawingFigure 4

AI summary

The present relates to compounds of formula (I) as defined herein. The compounds are suitable for protection against ultraviolet (UV) radiation. Further, the present invention is concerned with compositions comprising at least one compound of formula (I).