Phytochemical Profiling and Bioactive Potential of <i>Rhizoclonium hookeri</i> , Antioxidant, Antidiabetic, and Neuroprotective Effects

During the past two decades, algal-derived chemical constituents have garnered considerable attention, particularly for their pharmaceutical and nutraceutical applications. In this study, the phytochemical composition of the freshwater alga Rhizoclonium hookeri was investigated, alongside an evaluation of its pharmacological potential. Results of the study revealed that the total phenolic content (TPC) and total flavonoid content (TFC) were found to be higher in n-butanol compared to DCM extract. Antioxidant activity evaluated by ABTS, DPPH, and H₂O₂ assays demonstrated higher antioxidant potential by DCM extract, exhibiting distinct IC₅₀ values for each assay. In vivo antidiabetic assays revealed that the DCM extract significantly reduced blood glucose levels in alloxan-induced diabetic rats, with marked reductions observed from the first day of treatment (85.33 ± 4.13 mg/dL). Furthermore, the DCM extract exhibited stronger α-amylase inhibitory activity than the n-butanol extract, with IC₅₀ values of 48.18 and 404.06 µg/mL, respectively. Neurobehavioral assessments indicated that both extracts enhanced locomotor activity in the open-field test, with the n-butanol extract demonstrating a slightly higher anti-anxiolytic effect. In addition, acetylcholinesterase inhibition assays showed that the DCM extract possessed a more potent inhibitory effect (IC₅₀ = 15.71 µg/mL) compared to the n-butanol extract (IC₅₀ = 63.25 µg/mL). Collectively, these results demonstrate that R. hookeri extracts possess significant bioactive constituents and exhibit potent pharmacological activities, with the DCM extract showing enhanced antioxidant, antidiabetic, neurobehavioral, and enzyme inhibitory effects. These findings highlight the potential of R. hookeri as a promising source for the development of novel therapeutic agent.