In vitro effects of 1α,25(OH)₂D₃-glycosides from Solbone A (Solanum glaucophyllum leaves extract; Herbonis AG) compared to synthetic 1α,25(OH)₂D₃ on myogenesis.

The presence of glycoside derivatives of 1α,25(OH)2D3 endows plants to gradual release of the free bioactive form of 1α,25(OH)2D3 from its glycoconjugates by endogenous animal tissue glycosidases. This results in increased half-life of the hormone in blood when purified plant fractions are administered for therapeutic purposes. In this work, we evaluated the role 1α,25(OH)2D3-glycosides enriched natural product (Solbone A) from Solanum glaucophyllum leaf extract compared with synthetic 1α,25(OH)2D3 on myogenic differentiation in C2C12 myoblasts. For these, differentiation markers and myogenic parameters were studied in C2C12 myoblasts. Results showed that Solbone A, likewise the synthetic hormone, increased creatine kinase activity at day 2 after differentiation induction (60%, p<0.05). Solbone A and synthetic 1α,25(OH)2D3 increased vitamin D3 receptor protein expression at 10nM (50% and 30%, respectively) and the transcription factor myogenin (80%, p<0.05). However, tropomyosin expression was not affected by both compounds. In addition, myosin heavy chain (MHC) protein expression was increased 30% at day 2 of differentiation. Solbone A or synthetic 1α,25(OH)2D3 had no effects on myogenin nor MHC cell localization. Cellular mass increased with myogenesis progression, being Solbone A more effective than synthetic 1α,25(OH)2D3. Finally, Solbone A, as well as synthetic 1α,25(OH)2D3, augmented the index fusion of cultured muscle fibers. In conclusion, these results demonstrated that Solbone A exhibit at least equal or greater effects on early myoblast differentiation as synthetic hormone, suggesting that plant glycosides could be an effective, accessible and cheaper substitute for synthetic 1α,25(OH)2D3 to promote muscle growth.