Low molecular weight Spirulina peptides (200-600 Da) boost endurance and antioxidant defense in mouse exercise fatigue model

Exercise-induced fatigue is a complex physiological state often characterized by oxidative stress, muscle damage, and metabolic imbalances, limiting performance and recovery. Current nutritional strategies aim to mitigate these effects, but a deeper understanding of specific bioactive compounds and their mechanisms is needed. Spirulina, a blue-green algae, is recognized for its rich protein and antioxidant content, making its derived peptides promising candidates for sports nutrition. However, the precise relationship between peptide molecular weight and anti-fatigue efficacy, particularly concerning energy metabolism and antioxidant defense, remains underexplored.

Researchers enzymatically hydrolyzed Spirulina powder to produce bioactive peptides, optimizing hydrolysis conditions (55 °C, 1:10 feed-water ratio, 4% enzyme, 9 h) via response surface methodology. The resulting peptides were then fractionated by membrane filtration into different molecular weight (MW) ranges. These fractions were subsequently tested in a swimming-based mouse model of exercise fatigue. The primary endpoints included endurance performance, blood fatigue markers (blood urea nitrogen, blood lactate), antioxidant status, serum lipid indices, and key energy metabolism pathway readouts like AMPK and ACC.

The optimized hydrolysis yielded 46.30% peptides, containing 62.7 g/100 g total amino acids, particularly rich in glutamic and aspartic acid. Peptide fractions exhibited MW-dependent antioxidant characteristics: the 200-600 Da fraction showed rapid radical-scavenging, while the 1000-1500 Da fraction displayed more sustained activity. In the exercise fatigue model, the 200-600 Da fraction (referred to as peptide no. 1) demonstrated the most significant benefits. This fraction improved endurance performance, reduced accumulation of blood urea nitrogen and blood lactate, and enhanced overall antioxidant status. Furthermore, it improved serum lipid-related indices. These beneficial effects were associated with altered 5'-adenosine monophosphate-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) related readouts, suggesting a role in regulating energy metabolism.

The 200-600 Da Spirulina peptide fraction produced the most favorable overall anti-fatigue effects in mice, linking specific molecular weight to enhanced performance and metabolic regulation.