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]

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]

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]

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]

Rosmarinic acidPlectranthus amboinicus CIA model   
In vitro
TRAP, pit formation [20]   
NFATc1 [20]

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]

Genistein Lupin, fava beans, soybeans, and coffeeRat CIA modelIFN-γ , IL-4 ↑ [27], ERK, MAPK [28]

LupeolCalatropis gigantean Rat AA modelTNF-α, IL-1β, IL-6 [29]

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]

NaringinCitrus fruitsRat CIA modelClinical score , histology [32]

HesperidinCitrus fruitsRat CIA modelClinical score , histology [33]

CapsaicinCapsicum Osteoarthritis
in rat  
In vitro  
Bone erosion and trabecular damage [34]   
MMP-9, FAK/Akt, PKC/Raf/ERK, p38 (MAPK), AP-1 [35]

Ferulic acidCoffee, apple, rice Ovariectomy-induced rats Bone remodeling ↑ [36]

Oleuropein aglycone Olive oilMouse CIA modelHistological damage [37]

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]

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]

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]