Table 1.

Summary of studies reporting the role of natural dietary ingredients involved in the maintenance of protein homeostasis in sarcopenia prevention.

Natural Dietary Ingredients	Experimental Model	Experimental Designs	Results 1 (by Natural Dietary Ingredient Treatment)	Related Mechanisms (Potential Pathway)	Ref.
Botanical and marine extracts (bioactive compound)
Tannase-converted green tea extract	ICR mice	- aged mice (24-month-old) - aged mice with tannase-converted green tea extract	↑ MyoD, myogenin ↓ p-FoxO3a, myostatin, MuRF1, atrogin-1 ↑ lean mass	↑ myogenesis ↓ protein degradation (UPS; FoxO3 pathway)	[91]
WST	C2C12 myotube	- PBS and WST - TNF-α/IFNγ and WST - Dex and WST	↑ myogenin, p-p38 ↑ myotube diameter ↑ the number of nuclei inside myotube, total nuclei ↑ MHC type II, p-Akt	↑ myogenesis (p38 MAPK/myogenin pathway) ↑ protein synthesis (PI3K/Akt pathway)	[92]
	Human (Vastus lateralis muscle biopsies)	- young subjects - sarcopenic subjects	↑ myotube diameter ↑ the number of nuclei inside myotube ↑ MHC expression	↑ myogenesis
Leonurus japonicus extract (leonurine)	L6 myotube	- Non-treatment - TNF-α and L. japonicus extract or leonurine	↑ p-PI3K, p-Akt, p-mTOR, p-p70S6K, p-4E-BP1 ↑ p-FoxO3 ↓ atrogin-1, MuRF1 ↑ myotube diameter	↑ protein synthesis (PI3K/Akt pathway) ↓ protein degradation (UPS; FoxO3 pathway)	[93]
Chrysanthemum morifolium Ramat. extract (isochlorogenic acid A)	L6 myotube	- Non-treatment - TNF-α - TNF-α and C. morifolium Ramat. extract or isochlorogenic acid A	↑ p-PI3K, p-Akt, p-mTOR, p-p70S6K, p-4E-BP1 ↓ p-FoxO3 ↓ atrogin-1, MuRF1	↑ protein synthesis (PI3K/Akt pathway) ↓ protein degradation (UPS; FoxO3 pathway)	[94]
Oligonol	SAMP8 mice	- SAMR1 control mice (32-week-old) - SAMP8 mice (32-week-old) - SAMP8 mice with oligonol (for 8 weeks)	↑ p-Akt, p-mTOR, p-p70S6K ↓ nuclear localization of FoxO3a and NF-κB ↓ atrogin-1, MuRF1 ↓ Atg13, LC3-II, p62 ↑ CSA, grip strength, muscle mass	↑ protein synthesis (PI3K/Akt pathway) ↓ protein degradation (UPS; FoxO3 pathway, autophagy)	[95]
Phytochemicals
Isobavachalcone	C2C12 myotube	- Non-treatment - TNF-α - TNF-α and isobavachalcone	↑ myogenin, MyoD, MHC, myotube diameter ↓ atrogin-1, MuRF1, p-FoxO1	↑ myogenesis ↓ protein degradation (UPS)	[96]
Corylifol A	C2C12 myotube	- Non-treatment - Dex - Dex and corylifol A	↑ p-Akt, MHC ↓ atrogin-1, MuRF1, myostatin ↑ number of multinucleated myotube	↑ protein synthesis ↓ protein degradation (UPS)	[97]
β-Cryptoxanthin	SAMP1 mice	- SAMR1 control mice (20-week-old) - SAMP1 mice (20-week-old) - SAMP1 mice with β-Cryptoxanthin (for 15 weeks)	↓ beclin1, p62, LC3-I, LC3-II ↑ mass, CSA, MHC type I (soleus)	↓ protein degradation (autophagy) ↑ muscle hypertrophy	[98]
Probiotics
Lactobacillus plantarum HY7715	Balb/c mice	- young mice (7-week-old) - aged mice (81-week-old) - aged mice with HY7715 (for 5 weeks)	↓ atrogin-1, MuRF1 ↑ mass (soleus, gastrocnemius) ↑ CSA, MyoD, MHC type I	↓ protein degradation (UPS) ↑ muscle hypertrophy	[99]

¹ ↑, increase; ↓, decrease. Name of target which expression was determined in gene level was italicized. Abbreviations: Akt, protein kinase B; Atg, autophagy-related; CSA, cross-sectional area; Dex, dexamethasone; FoxO3, forkhead box O3; IFNγ, interferon gamma; LC3, light chain 3; MAPK, mitogen-activated protein kinase; MHC, myosin heavy chain; mTOR, mammalian target of rapamycin; MuRF1, muscle RING-finger protein-1; MyoD, myogenic differentiation 1 protein; NF-κB, nuclear factor kappa B; PI3K, phosphatidylinositol 3-kinase; p70S6K, ribosomal protein S6 kinase; SAMP, senescence-accelerated mouse prone; SAMR, senescence-accelerated mouse resistance; TNF-α, tumor necrosis factor-alpha; UPS, ubiquitin-proteasome system; WST, Withania somnifera, Silybum marianum, Trigonella foenum-graecum formulation; 4E-BP1, 4E-binding protein 1.