Antioxidant Potential of Myrciaria tenella Fruit Extracts: In Vitro and In Vivo Protection Against Oxidative Stress

<i>Myrciaria tenella</i> (cambuí) is a native Brazilian fruit traditionally recognized for its sensory attributes and medicinal properties, including antidiabetic, anti-inflammatory, antimicrobial, and gastroprotective activities. This study evaluated the antioxidant activity of unripe and ripe <i>M. tenella</i> fruits using in vitro and in vivo experimental models. Four extracts were prepared: aqueous unripe (VA), aqueous ripe (MA), hydroethanolic unripe (VE), and hydroethanolic ripe (ME). Antioxidant activity was assessed through biochemical assays and cellular models using NIH/3T3 fibroblasts and RAW 264.7 macrophages. In RAW 264.7 cells, oxidative stress modulation was investigated using hydrogen peroxide-induced stress and lipopolysaccharide (LPS)-stimulated nitric oxide (NO) production. In NHI/3T3 cells, wound healing, copper sulphate (CuSO₄)-induced oxidative stress, intracellular reactive oxygen species (ROS) generation, and nuclear morphology following DAPI staining were evaluated. Total phenolic content was quantified using the Folin-Ciocalteu method and analyzed by HPLC-DAD. In vivo toxicity and antioxidant protection were assessed using <i>Tenebrio molitor</i> larvae exposed to CuSO₄-induced oxidative stress. Among the extracts, VE exhibited the highest metal-chelating activity (Cu: 78.6%; Fe: 37.7%) and total phenolic content (50.64 mg GAE/mg). HPLC-DAD analysis identified gallic acid in all extracts, kaempferol derivatives in hydroethanolic extracts (VE and ME), and catechin derivatives in aqueous extracts (VA and MA). All extracts were non-cytotoxic and demonstrated protective effects against oxidative stress in vitro. In vivo assays confirmed the absence of toxicity and significant antioxidant protection, with VE resulting in 80% larval survival.