Table 1: Natural products that have antiarthritic/bone protective property.
PhytochemicalSourceModel usedIn vivo/in vitro activity Structure
Epigallocatechin-3-gallate (EGCG)Green tea (Camellia sinensis)Cocktail of monoclonal antibodies against collagen [5], AA model [6]   
  
In vitro		Clinical score, histology ↓ [5], histology, radiology, TNF-α, IL-6 ↓ [6]; iNOS, nitric oxide, MMP-1 and MMP-13, glycosaminoglycan, osteoclastogenesis ↓   
  
NF-κB, c-Fos, NFATc ↓ [7]		518094.tab.001
Curcumin Turmeric
(Curcuma longa)		CIA rat model
  
  
In vitro		Clinical score, TNF-α, IL-1β, NF-κB ↓; iNOS, PGE2, COX-2, IL-6, IL-8, MMP-3, MMP-9 ↓ [8]
  
PGE2, COX-2, MMP, NF-κB ↓ [9] 		518094.tab.002
Celastrol Celastrus species AA rat model
  
  
  
In vitro  
TNF-α, IL-1β, IL-6, IL-17, IL-18 ↓ [10, 11], RANKL,
osteoclast ↓ [11]   
  
STAT3, MMP-9, pERK ↓ [12], NF-κB, IκB-α kinase, p-IκB-α, p-p65 ↓ [13, 14], p-JNK, p-c-Jun and NF-κB ↓ [15], AKT/mTOR [16], angiogenesis ↓ [16, 17]		518094.tab.003
Resveratol Grapes
(Vitis vinifera)		CIA model   
  
  
In vitro  
Clinical score, IL-17, IL-1 ↓ [18]   
  
ROS, PGE2, MMPs ↓ in vitro.
Proteoglycan synthesis and chondrocyte proliferation ↑ [19]		518094.tab.004
Rosmarinic acidPlectranthus amboinicus CIA model   
  
In vitro		TRAP, pit formation ↓ [20]   
  
NFATc1 ↓ [20]		518094.tab.005
Boswellic acid, AKBABoswellia plantsBSA-induced arthritis in rabbits, carrageenan- induced edema  
  
  
  
In vitro  
  
Leukocyte infiltration ↓ [21, 22]   
  
  
  
Phosphorylation of ERK-1/2 ↓ [23], STAT3 ↓ [24], NF-κB ↓ [25], angiogenesis ↓ [26]		518094.tab.006
Genistein Lupin, fava beans, soybeans, and coffeeRat CIA modelIFN-γ ↓, IL-4 ↑ [27], ERK, MAPK ↓ [28]518094.tab.007
LupeolCalatropis gigantean Rat AA modelTNF-α, IL-1β, IL-6 ↓ [29]518094.tab.008
6-ShogaolGinger (Zingiber officinale) CFA-induced monoarthritic model of the knee joint of rats  
  
In vitro  
Infiltration of leukocytes, cartilage protection [30]   
  
  
MMP-9, NF-κB, IκB phosphorylation ↓ [31]		518094.tab.009
NaringinCitrus fruitsRat CIA modelClinical score ↓, histology [32]518094.tab.0010
HesperidinCitrus fruitsRat CIA modelClinical score ↓, histology [33]518094.tab.0011
CapsaicinCapsicum Osteoarthritis
in rat  
    
  
In vitro  
 Bone erosion and trabecular damage ↓ [34]   
  
  
MMP-9, FAK/Akt, PKC/Raf/ERK, p38 (MAPK), AP-1 ↓ [35]   
518094.tab.0012
Ferulic acidCoffee, apple, rice Ovariectomy-induced rats Bone remodeling ↑ [36]518094.tab.0013
Oleuropein aglycone Olive oilMouse CIA modelHistological damage ↓ [37]518094.tab.0014
QuercetinOnionOveriectomy-induced rats  
  
  
In vitro  
Osteoclast differentiation, osteoclast-related genes ↓ [38]   
  
MMP-1, 3, COX-2, PGE2
phosphorylation of ERK-1/2, p38, JNK, NF-κB ↓ [39]		518094.tab.0015
Silibinin Silymarin In vitro  
  
  
RAW 264.7 cells,
MC3T3 cells  
  
 Osteoclasts, OSCAR, NFATc1, Cat K, MMP-9, RANKL ↓ [9],   
  
  
ERK 1/2 and c-Jun phosphorylation ↓ [40]   
518094.tab.0016
Total flavonoid of orange (TFO)OrangeRat AA modelTNF-α, IL-1β, PGE2 and COX2 ↓ [41] 
Highly oligomeric procyanidins (HOPCs)JatobaMouse CIA modelClinical score, joint histology ↓ [42] 
Green tea polyphenol (GTP)Green tea (Camellia sinensis)CIA, AA modelCOX-2, TNF-α, IFN-γ ↓ [43], clinical score, IL-17 ↓, IL-10 ↑ [44] 
Proanthocyanidin Grape seedsMouse CIA modelClinical score, IL-17, IL-21, IL-22 ↓, Foxp3 ↑ [45]