Protective effects of 7-hydroxyethyl chrysin on rats with exercise-induced fatigue in hypobaric hypoxia environment

Preparation of copolymer 7-hydroxyethyl chrysin loaded PLGA nanoparticles and the in vitro release

OBJECTIVES

To prepare 7-hydroxyethyl chrysin (7-HEC) loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles and to detect the in vitro release.

METHODS

The 7-HEC/PLGA nanoparticles were prepared by emulsification solvent volatilization method. The particle size, polydispersity index (PDI), encapsulation rate, drug loading and zeta potential were measured. The prescription was optimized by single factor investigation combined with Box-Behnken response surface method. Mannitol was used as protectant to prepare lyophilized powder, and the optimal formulation was characterized and studied for the in vitro release.

RESULTS

The optimal formulation of 7-HEC/PLGA nanoparticles was as follows: drug loading ratio of 2.12∶20, oil-water volume ratio of 1∶14.7, and 2.72% soybean phospholipid as emulsifier. With the optimal formulation, the average particle size of 7-HEC/PLGA nanoparticles was (240.28±0.96) nm, the PDI was 0.25±0.69, the encapsulation rate was (75.74±0.80)%, the drug loading capacity was (6.98±0.83)%, and the potentiostatic potential was (－18.17±0.17) mV. The cumulative in vitro release reached more than 50% within 48 h.

CONCLUSIONS

The optimized formulation is stable and easy to operate. The prepared 7-HEC/PLGA nanoparticles have uniform particle size, high encapsulation rate and significantly higher dissolution rate than 7-HEC.

Beneficial effects of a novel polyherbal formulation on the skeletal muscle antioxidant status, inflammation, and muscle-signaling proteins in exercised rats

Background/aim

Exhausting exercise can damage muscle tissue due to free radical interactions. It is hypothesized that the increase in free radicals following muscle injury, either due to oxidative damage to biomolecules or the activation of inflammatory cytokines, may lead to secondary muscle damage. This study investigated the effects of a novel joint health formula (JHF) containing bisdemethoxycurcumin-enriched curcumin, 3-O-Acetyl-11-keto-beta-boswellic acid-enriched Boswellia (AKBA), and Ashwagandha on exhaustion time, grip strength, antioxidant status, and muscle-signaling proteins in exhaustively exercised rats.

Materials and methods

Twenty-eight rats were divided into four groups: Control (C), exercise (E), E + JHF 100 (100 mg/kg), and E + JHF 200 (200 mg/kg).

Results

An increase in time to exhaustion and grip strength was recorded with JHF supplementation in a dose-dependent manner (p < 0.0001). In addition, serum and muscle lactate dehydrogenase, malondialdehyde, myoglobin, creatine kinase, and lactic acid concentrations were decreased in the groups supplemented with JHF, particularly at the high dose of JHF (200 mg/kg) (p < 0.0001 for all). JHF supplementation also increased antioxidant enzyme activities and suppressed the production of inflammatory cytokines compared to the exercise group (p < 0.0001). Moreover, JHF reduced the levels of PGC-1α, p-70S6K1, MAFbx, MuRF1, and p-mTOR proteins in muscle tissue compared to the exercise group (p < 0.05), being more effective at high doses.

Conclusion

These findings show that JHF might reduce muscle damage by modulating antiinflammatory, antioxidant, and muscle mass regulatory pathways in exhausted training rats. At the same time, JHF improved exercise performance and grip strength.