Microplastic exposure and its association with antioxidant responses and biochemical constituents in Anadara granosa

Microplastic pollution has emerged as a global environmental threat with potential implications for aquatic organisms and food safety. However, the relationship between physiological stress responses and bioactive compound production in bivalves remains poorly understood. Exposure affects the organism's ability to adapt by producing bioactive compounds with antioxidant properties. This study investigated the responses of antioxidant biomarkers and the profile of bioactive compounds in Anadara granosa (Linnaeus, 1758) in relation to microplastic pollution across two contrasting estuarine ecosystems in South Sumatra, Indonesia. Anadara granosa samples (n = 30 per size category: small 5–10 g, medium 11–15 g, and large 16–20 g) were analysed for antioxidant capacity using the DPPH assay, microplastic content through three digestion methods (HNO₃ 69%, KOH 10%, and H₂O₂ 30%), and bioactive compounds usssing GC–MS. Microplastic polymers were identified using FT–IR, while variable associations were analysed using PCA and AHC. The results revealed a higher microplastic load in A. granosa from the Musi Estuary compared to the Barong Mudflat. Specific microplastic characteristics, including particle types (pellets, fragments, films), colours (black, yellow, green, transparent), and polymers (PS, ABS), were associated with variations in antioxidant biomarker responses in A. granosa . The enhanced antioxidant activity, reflected by lower IC₅₀ values, was mainly linked to ethylene glycol, lipid groups, and pyran derivatives. This study provides preliminary evidence that microplastic contamination can influence antioxidant biomarker responses and bioactive compound profiles in A. granosa . These findings support the potential use of antioxidant responses and biochemical profiles as ecotoxicological biomarkers, with broader implications for estuarine ecosystem health and seafood safety.