Table 2.

Summarized experimental studies and anti-cancer mechanisms of action of SLs

Tested compound/source	Cancer tested model	Mechanisms of action	Refs.
Guaianolides (Cynara scolymus) Cynaropicrin	leukocyte cancer cells in vitro	↓invasion ↓migration ↓metastasis	[150]
	U937 cells in vitro	↑apoptosis ↑cell cycle stall at the G1/S stage	[151]
	DU145 human prostate cancer cells in vitro	↑anti-apoptotic genes ↑Bcl-2, ↓IL-6, ↓STAT3 ↓intracellular GSH	[152]
	Keratinocytes cells in vitro	↓TrxR ↓NF-κB	[132]
Pseudoguaianolides (Arnica montana) Helenalin	A2780 human ovarian cancer cells RKO colon carcinoma cancer cells MCF-7 breast adenocarcinoma cancer cells in vitro	↑autophagic cell death ↑caspase activity	[153]
Eudesmanolide (Spilanthes acmella and Taraxacum officinale)	MCF-7 breast cancer cells in vitro	↓ metastasis ↓colony formation	[154]
	HEP-2 HT-29 liver cancer cells in vitro	↓ROS ↑apoptosis ↓cancer cells growth	[155]
	DLA Dalton’s lymphoma ascites cells V79 Chinese hamster lung carcinoma in vitro	↑DNA damage ↓ROS	[156]
	MCF-7AZ breast cancer cells LNCap prostate cancer cells in vitro	↓cancer cells growth ↓PI3K/AKT	[157] [141]
	A375 human melanoma cells in vitro	↑apoptosis ↑caspase-8	[144]
	SH-SY5Y neuroblastoma cells in vitro	↑cytotoxic activity
	mice in vivo	↓tumor size	[157]
Melampodinin A (Melampodium spp.)	PC-3 DU145 Hela in vitro	seizure of the cell cycle at the G2/M stage ↑abnormal mitotic spindle cycle ↑cytotoxicity	[145]
Germacrene (Solidago spp.) germacrene D	Hepg2 liver carcinoma cells breast MCF7 carcinoma cells cervix Hela carcinoma cells in vitro	↑cytotoxic activity	[147]
	SMMC- 7721 SGC-7901 Hela in vitro	↑cytotoxic activity	[158]

Symbols: ↑increase, ↓decrease