LOBEIRA STARCH INCLUSION COMPLEXES WITH MIRINDIBA EXTRACTS: IMMUNOMODULATORY EFFECT IN TYPE 2 DIABETES MELLITUS

The Cerrado biome has several plant species that are relevant sources of bioactive compounds with antioxidant, anti-inflammatory and metabolic modulator potential. Lobeira (Solanum lycocarpum) stands out as a potential source of resistant starch, associated with hypoglycemic and antioxidant effects, while mirindiba (Buchenavia tomentosa Eichler) has a high content of phenolic compounds, flavonoids, carotenoids and vitamin C. The complexation between lobeira starch and hydrophilic and lipophilic extracts of mirindiba can intensify its functional properties, and the objective of this study is to evaluate the immunomodulatory effects of these complexes in experimental model of type 2 diabetes mellitus, correlating its physicochemical, bioactive and antioxidant characteristics with potential therapeutic applications. The fruits of lobeira and mirindiba were collected in Barra do Garças-MT, stored at 18 °C and processed to obtain starch and extracts. The lobeira showed high moisture (79.42 g/100 g), proteins (7.08 g/100 g), low lipid content (0.67 g/100 g), ash (3.31 g/100 g) and carbohydrates (9.52 g/100 g). Mirindiba showed high levels of total phenolic compounds (1362.7 mg gallic acid/100 g), phenolic acids (73.86 mg caffeic acid/100 g), flavonoids (100.14 mg quercetin/100 g) and carotenoids (7.07 mg β-carotene/100 g), confirmed by the DPPH (140.19 μmol Trolox/g) and FRAP (58.42 μmol Trolox/g) antioxidant capacity assays. Lobeira starch showed a yield of 55.55% and was characterized by FTIR, SEM, XRD and TG/DSC.FTIR revealed hydrophilic interactions with phenolic compounds and hydrophobic interactions with carotenoids from the lipophilic extract. SEM showed oval and homogeneous granules in native starch, whereas hydrophilic complexes exhibited a rough surface and lipophilic complexes displayed fragmentation and compacted regions. XRD indicated type-C crystallinity in native starch with peaks at 15°–23° (2θ), partial reduction in hydrophilic complexes, and a greater transition to the amorphous phase in lipophilic ones. TG/DSC analysis showed main degradation between 300–340 °C in the hydrophilic complex and higher thermal stability in the lipophilic complex (250–350 °C). Biological assays with human peripheral blood mononuclear cells demonstrated high cell viability (>96%) in all samples. Native starch induced lower stimulation of superoxide anion production, whereas the complexes reduced oxidative stress in co-cultures with Escherichia coli. Superoxide dismutase (SOD) activity increased in normoglycemic cells and was partially restored in diabetic cells treated with the complexes, indicating an antioxidant and adaptive immunomodulatory effect. In conclusion, lobeira starch complexed with mirindiba extracts exhibits biocompatibility, antioxidant, and immunomodulatory properties, suggesting therapeutic potential for diabetes and infections.