# Physicochemical Characterization and In Vitro Anti-Inflammatory Assessment of Novel Sodium Alginate Sponges Loading Andiroba Oil (Carapa guianensis Aubl.) for Skin Dressings

## TL;DR

This study develops and tests sponges made from sodium alginate loaded with andiroba oil for their potential as anti-inflammatory skin dressings.

## Contribution

A novel formulation of sodium alginate sponges loaded with Amazonian andiroba oil is proposed for topical anti-inflammatory applications.

## Key findings

- Andiroba oil-loaded sponges showed structural changes and favorable interactions with the alginate matrix.
- Oleic acid from andiroba oil exhibited strong binding affinity to anti-inflammatory targets like NF-kB and iNOS.
- The sponges significantly reduced nitric oxide production in macrophages without harming cell viability.

## Abstract

This study describes the structural characterization
of a novel
formulation based on sodium alginate sponges loading the Amazonian andiroba oil (Carapa guianensis Aubl.) as a strategy for developing topical anti-inflammatory dressings.
The characterization by X-ray diffraction revealed the amorphous profile
of unloaded and andiroba oil-loaded sponges, indicating
structural flexibility suitable for modifying the release profile
of bioactives. Scanning electron microscopy revealed a porous, interconnected
structure of the unloaded alginate sponges, whereas oil-loaded sponges
exhibited smoother, thicker pore walls and localized densification,
indicating the oil’s influence on the polymeric matrix architecture.
Fourier transform infrared spectra identified the ester, hydroxyl,
and carboxylate groups, confirming the chemical signature of the andiroba oil and its interactions with the alginate matrix.
Hirshfeld surface analysis of oleic acid, one of the main bioactive
components of andiroba oil, revealed a predominance
of hydrophobic contacts and hydrogen-bonding interactions, supporting
its affinity for biological targets. Surface analysis also indicated
high porosity (∼70% void volume), suggesting a potential application
for topical delivery. Docking simulations showed favorable binding
affinity of oleic acid to the active site of NF-kB (−5.75 kcal/mol)
and iNOS (−5.15 kcal/mol), corroborating its anti-inflammatory
potential. In silico pharmacokinetic profiling exhibited
low skin permeation (Log K
p = −2.6
cm/s) of oleic acid, no blood–brain barrier penetration, and
no interaction with P-glycoprotein. Andiroba oil-loaded
sponges significantly reduced nitric oxide production in lipopolysaccharide-activated
RAW 264.7 macrophages without affecting cell viability. The unloaded
alginate sponges also showed mild nitric oxide inhibition at high
concentration, confirming their inherent biocompatibility. Altogether,
these findings support the use of the developed sponges as a promising
bioactive dressing for the healing of inflamed wounds and other chronic
skin conditions, combining Amazonian phytotherapy with innovative
polymeric delivery systems.