Biocompatibility, anti-inflammatory, and antimicrobial properties of Kaurenoic acid recovered from synthetic biology by-products: a sustainable approach to food bioactives

Kaurenoic acid (KA) is a diterpenoid with recognized anti-inflammatory and antimicrobial activities, but its use as a functional ingredient is limited by sustainability concerns associated with plant extraction and by its poor water solubility. This study evaluates whether kaurenoic acid produced through synthetic biology (S-KA) differs from a commercially available natural-derived standard (G-KA) and assesses the bioactivity of S-KA and its more soluble sodium salt derivative (KNa). GC–MS analysis revealed that S-KA possessed higher purity (99.06%) than the commercial equivalent (98.83%). Structural characterization via FTIR-ATR, DSC, and XRD confirmed that S-KA is structurally equivalent to natural KA. The synthesis of KNa successfully addressed the molecule’s hydrophobicity, increasing water solubility by approximately 300-fold (3.87 mg/mL) compared to the free acid (0.013 mg/mL). Regarding biological activity, both S-KA and KNa showed no cytotoxicity towards human macrophages and keratinocytes up to 60 µg/mL. In anti-inflammatory assays, both compounds significantly inhibited the expression of pro-inflammatory cytokines (IL-6, IL-8, and TNF-α) in specific patterns comparable to betamethasone, while exhibiting a distinct total inhibition of IL-10. Furthermore, S-KA and KNa demonstrated antimicrobial activity against Gram-positive bacteria, with Minimum Inhibitory Concentrations (MIC) ranging from 25 to 50 µg/mL against Staphylococcus aureus and Staphylococcus epidermidis. These findings demonstrate that synthetic biology offers a sustainable, high-purity alternative to natural extraction, and that salt derivation effectively overcomes solubility barriers for food and dermal applications.