Elderberry Extracts increase Rat L6 Myocyte proliferation, reduce Apoptosis and act as HDAC1/SIRT1 Agonists in vitro

Abstract

Sarcopenia is a geriatric syndrome that is characterized by low muscle mass, strength, and function, that increases morbidity and mortality, and the rates of hospitalization and nursing home admissions in geriatric populations. Poor nutritional intake and alterations in the muscle response to anabolic stimuli from meals in aging populations contribute to the overall pathogenesis of sarcopenia. Research has suggested that there is an increase in skeletal myocyte apoptosis in aging populations. The extent of apoptosis in muscle increases with increasing age, which parallels the loss of both muscle mass and strength. Myocyte apoptosis may be reduced by caloric restriction, exercise training, hormone supplements, drugs and various nutritional supplements. Sambucus nigra L. (Adoxaceae), also known as elderberry is a deciduous tree with blue‐black fruits and cream‐white flowers. Elderberry has been used in traditional systems of medicine to for its antiviral activities, to reduce inflammation and diabetic symptoms. The chemical constituents of elderberry include the flavonoids, such as flavonols, proanthocyanidins and anthocyanins, and simpler phenolic acids. This study investigated the effects of elderberry extracts in rat L6 myoblasts to determine the effects on cell proliferation and apoptosis. L6 cells were obtained from ATCC and cultured in Dulbecco’s Modified Eagle’s medium, with 2.5 mM L‐glutamine (without phenol red). Elderberry extracts were prepared in ethanol and partitions containing anthocyanins were prepared in acetone (SNA) and ethanol (SNE). In L6 cells, ethanol partitions of elderberry increased the proliferation of rat L‐6 myoblasts by 242% and prevented cellular apoptosis induced by serum starvation. The acetone partition increased cell growth by 121% in serum starved L6 cells, the extracts also prevented myoblast apoptosis. Gene expression analysis an increase in the anti‐apoptotic Bcl‐2 mRNA expression and a reduction in Bax expression, thereby reducing the Bax/Bcl‐2 ratio to reduce apoptosis. SNE also increased the expression of PPARγ mRNA by 6.5 fold. Peroxisome proliferator‐activated receptors (PPARs) are ligand‐activated transcription factors belonging to the nuclear receptor superfamily that regulate lipid metabolism, glucose homeostasis, cell proliferation, and differentiation and modulate inflammatory responses. SNE also increased the expression of HDAC1 by 6 fold and SIRT1 by 12 fold. The human Silent Information Regulator Type 1 (SIRT1) is an NAD(+)‐dependent deacetylase that is an intermediary of cellular metabolism in gene silencing and aging. SIRT1 has been extensively investigated and shown to delay senescence and cellular apoptosis. The data suggest that SNE reduces myocyte apoptosis and that the extracts and partitions act as HDAC1/SIRT1 agonists in myocytes.Support or Funding InformationThis work was supported in part by a research grant from the Regenstein Foundation (GBM); a Postdoctoral fellowship award from the Schlumberger Foundation (TOL/GBM); and a Raman Post‐Doctoral Fellowship by the University Grants Commission, Govt. of India to NAR.