Table 1.

Chemical and mechanistic profile of phytochemicals.

Sr. No	Chemical classification	Phytoconstituents	Potential mechanism	Reference
1	Phenylpropanoid glycoside	Echinacoside	Increases OPG/RANKL ratio.	Li et al., 2013
2	Phenolic acid	Vanillic acid	Increases BMD and BMC.	Li et al., 2013
		Salvianolic acid B	Upregulates the expression of Runx2, OPN, ALP activity Increases BMP expression, Increases bone mass and diameters. Inhibits the over-production of NO and PGE2, INOS, COX-2, MMP-13, and ADAMTS-5 blocks the IL-1β induced phosphorylation of NF-κB signaling Increases post-fracture ALP activity	Cui et al., 2012 Li and Wang, 2017 Lou et al., 2017 He and Shen, 2014
3	Diterpenoid	Kirenol	Increases OPG/RANKL ratio Increases ALP, ColA1, OPN levels.	Kim et al., 2014
4	Flavonoid	Kaempferol	Increases BMP-2, RUNX-2, osterix, and collagen Inhibits p38, ERK 1/2, and JNK MAP kinase phosphorylation and expression of NFATc1 and c-Fos, enhances expression of Sox9, Runx2, OCN, collagen type I and collagen type X Upregulates the iNOS and Cox-2 expression, Inhibits NF-κB pathway	Kim et al., 2016 Nepal et al., 2013 Zhuang et al., 2017
		Rutin	Enhances the average thickness of trabecular bone Increases ALP activity and vitamin D levels	Zhuang et al., 2017 Abdel-Naim et al., 2018
5	Isoflavone	Neobavaisoflavone	Inhibits apoptosis of osteoblasts Increases Bcl-2 expression.	Chen S. et al., 2017
		Formononetin	Increases FOXP3 expression, Increases bone mechanical properties. Increases expression of VEGF, VEGFR-2/flk-1 ALP, OCN, OPN, and Col I	Mansoori et al., 2016 Huh et al., 2009
		Genistein	Restores bone volume Decreases the RANKL-induced osteoclastic differentiation	Yamaguchi and Levy, 2017
6	Sesquiterpene	Costunolide	Increases VEGF/HO-1 pathways Decreases luciferase activity and Runx2 expression	Lee and Choi, 2011a
7	Stilbene	Kobophenol A	Increases ALP activity Increases Bcl-2 level Decreases Bax expression	Kwak et al., 2013
8	Stilbene	Resveratrol	Decreases serum levels of ALP and OC Increases protein expression of SIRT1 Blocks the expression of TNF-α, IL-1β, IL-6 and IL-18, nitric oxide synthase, nuclear factor (NF)-κB, and reduces caspase-3/9 activity Blocks TLR4 signaling pathway Decreases serum and synovial fluid levels of IL-1β, IL-10, IL-6, TNF-α, MMP-13, and osteocalcin	Kwak et al., 2013 Wei et al., 2018 Jiang et al., 2017 Wang et al., 2016
9	Phytoestrogen	Puerarin	Increases femur trabecular bone structure Involves of ERK1/2 and p38- MAPK pathway	Zhang et al., 2017
10	Prenylated flavonol glycoside	Icariin	Blocks the cAMP/ PKA/ CREB signaling pathway Increases intracellular cAMP levels and PKA and CREB pathways Increases CTX and OC levels and decreases IL-6 levels Decreases phosphorylated p38 and JNK levels, β-catenin levels, MMP-13 levels Inhibits NF-kappaB pathway	Shi et al., 2017 Gao et al., 2017 Zeng et al., 2014 Wei et al., 2017
11	Polyphenol	Tanshinol	Increases FoxO3a and Gadd45a, Decreases canonical Wnt signaling pathway (β-catenin and Axin2)	Yang et al., 2018
12	Steroidal glucoside	Ophiopogonin D	Increases proliferation of MC3T3-E1 cells Decreases TRAP activity Decreases ROS generation	Yang et al., 2018
13	Flavonoid	Ugonin K	Increases proliferation of MC3T3-E1 osteoblasts Increases BSP, OCN levels	Lee et al., 2011 Huang Q. et al., 2015
		Poncirin	Increases bone mineral density, Increases serum OC, Runx2 protein production, expression of OC and OPG mRNA, ALP activity	Lin et al., 2017
		Naringin	Increases BMP-2 expression response via the PI3K, Akt, c-Fos/c-Jun, and AP-1-dependent signaling pathway Increases ALP activity and OCN level Increases the apoptosis of osteoclasts Inhibits RANKL-induced phosphorylation of ERK Reduces synthesis of PGE2, NO, IL-6, and TNF-α	Ang et al., 2011 Wu et al., 2008 Xu et al., 2017