The brown alga Padina pavonica methanol and hexane partitions prevented depressive behavior induced by dexamethasone in mice.

Background and purpose: Padina pavonica, a brown alga, displays protection against oxidative stress, neuroinflammation, and neurodegenerative disorders. Considering the beneficial effects of P. pavonica and since its antidepressant effects have not yet been studied, we investigated its methanol and hexane partitions (PMP and PHP) in mice model.

Experimental approach: In male mice (25 ± 2 g), depression was initiated by administrating dexamethasone (15 μg/kg) subcutaneously. PMP or PHP (80-160 mg/kg) was administered intraperitoneally. All the injections continued for two weeks. After the locomotor test, different depression criteria were evaluated by forced swim test (FST), marble burying test (MBT), sucrose preference (SP) test, and novelty-suppressed feeding test (NSFT).

Findings/results: PMP (160 mg/kg) showed antidepressant effects, immobility time decreased significantly during FST (84.6 ± 10.4 s) compared to the control, food intake increased significantly during NSFT (21.1 ± 2.5 mg/g) versus the control, and SP was 81%. PHP (80 mg/kg) reduced immobility time to 124.5 ± 6.7 s compared to the vehicle and increased the SP to 85%. Dexamethasone-induced depression. While co-treatment with PMP or PHP prevented depression initiated by dexamethasone. Only PHP reduced the number of buried marbles after 30 min against the control. The applied doses did not cause significant changes in the locomotor activity.

Conclusion and implications: PMP and PHP exhibited antidepressant-like effects in mice. PHP also reduced the number of buried marbles, implying a reduction in obsessive-like behavior. These observations underscore the constituents inherent in PMP and PHP, which merit further exploration to elucidate their potential therapeutic applications.