Extraction and Fractionation of the Seaweed Sargassum plagyophylum and Evaluation of Fractions on Depression Induced by Interferon Alpha in Mice

Background: Marine organisms such as seaweeds, produce potent chemicals with characteristic biological features. Sargassum species have great potential to be used for neuronal protection as part of nutraceuticals. The aim was to investigate the effects of hexane and methanol extracts of Sargassum plagyophylum from the Persian Gulf on depression induced by interferon‐α (IFNa) in mice. Materials and Methods: S. plagyophylum was extracted by maceration with methanol‐ethyl acetate solvent (1:1). The extract was evaporated and partitioned by hexane and methanol solvents. Male mice were used, depression was induced by SC injecting IFNα (16 × 10 5 IU/kg) for 6 days. Animals were subject to the forced swimming test (FST) after the locomotor test, on day 7. The extracts were administered IP either one single dose (acute) before the test, or simultaneously with IFNα (sub‐acute). Results: The locomotor activity was not different from control values. IFNa increased the immobility time during FST (140 ± 14 s vs. control group 95 ± 9 s, P < 0.05). Hexane extract acute (40 mg/kg) injection was not effective while its sub‐acute (20 mg/kg) injection reduced immobility time (46 ± 8 s, P < 0.001 vs. IFNa alone). Methanol extract acute (20 mg/kg) and sub‐acute (20 mg/kg) administration significantly reduced immobility during the FST (78 ± 20 s, and 72 ± 8 s respectively, P < 0.05 vs. IFNa alone). Conclusion: S. plagyophylum has antidepressant effects, the hexane extract could prevent depression while the methanol extract not only prevented but also treated depression induced by IFNa in mice. Since this species is abundant in the Persian Gulf further clinical studies on its psychological effects are warranted.