Table 3.

Natural alkaloids with pharmacological potential.

Name	Source	Antioxidant stress	Anti-inflammatory	Antiapoptosis	Promote matrix anabolism	Promote proliferation	Signal path	Type of study	References
Berberine	Rhizoma coptidis			Caspase-3, Bax↓, Bcl-2↑	Collagen II, aggrecan↑, MMP3/13, ADAMTS-4/5↓	CCK-8↑	NF-κB	B	[127]
		ROS↓		Caspase-3, Bax↓, Bcl-2↑		CCK-8↑	IRE1/JNK	A	[128]
				Caspase-3, Bax↓, Bcl-2↑	Collagen II, aggrecan↑, MMP13, ADAMTS-5↓		Autophagy	A	[129]
Oxymatrine	Sophora flavescens		IL-6↓	Hoechst 33258, flow cytometric analysis↓	Collagen II, aggrecan↑, MMP2/3/9/13↓	CCK-8↑	NF-κB	A	[131]
			IL-6↓	Hoechst 33258, flow cytometric analysis↓	Collagen II↑, MMP3/9↓			A	[132]
Piperine	Black pepper		IL-1β, TNF-α, IL-6, iNOS↓		Collagen II, aggrecan↑, MMP3/13, ADAMTS-4/5↓	CCK-8↑	NF-κB and MAPK	A	[135]

A: rat model of NP in vitro, in vivo. B: human model of NP in vitro.