Neuroprotective effects of roasted licorice, not raw form, on neuronal injury in gerbil hippocampus after transient forebrain ischemia.
OBJECTIVE
To observe neuroprotective effects of raw and roasted licorice against hypoxia and ischemic damage.


METHODS
When elucidating the protective effects of raw and roasted licorice, we analyzed the lactate dehydrogenase (LDH) release using PC12 cells after hypoxia in an in vitro study and after transient forebrain ischemia in an in vivo study on Mongolian gerbils.


RESULTS
Raw and roasted licorice significantly reduced LDH release from PC12 cells exposed to an hypoxic chamber for 1 h. In the roasted licorice-treated group, the decrease of LDH release was more pronounced compared to that of the raw licorice-treated group. In roasted licorice-treated animals, approximately 66%-71% of CA1 pyramidal cells in the ischemic hippocampus were stained with cresyl violet compared to the control group. However, in the raw licorice-treated animals, no significant neuroprotection against ischemic damage was shown. In addition, ischemic animals in roasted licorice-treated group maintained the Cu, Zn-superoxide dismutase (SOD1) activity and protein levels compared to the control group, while in raw licorice-treated group SOD1 activity and protein levels were reduced significantly. High pressure liquid chromatography analysis showed that non-polar compounds containing glycyrrhizin-degraded products, such as glycyrrhetinic acid (GA) and glycyrrhetinic acid monoglucuronide (GM), were increased in roasted licorice.


CONCLUSIONS
Roasted licorice had neuroprotective effects against ischemic damage by maintaining the SOD1 levels. In addition, the difference in protective ability between raw and roasted licorice may be associated with non-polar compounds, such as GA and GM.
Hwang
In-Koo
IK
Department of Anatomy, College of Medicine, Hallym University, Chunchon 200-702, Korea.
Lim
Soon-Sung
SS
Choi
Kyu-Hyun
KH
Yoo
Ki-Yeon
KY
Shin
Hyun-Kyung
HK
Kim
Eun-Ji
EJ
Yoon-Park
Jung-Han
JH
Kang
Tae-Cheon
TC
Kim
Young-Sup
YS
Kwon
Dae-Young
DY
Kim
Dong-Woo
DW
Moon
Won-Kook
WK
Won
Moo-Ho
MH
D000818:Animals; D015687:Cell Hypoxia; D004365:Drugs, Chinese Herbal / Q000302:isolation & purification / Q000494:pharmacology*; D005849:Gerbillinae; D006035:Glycyrrhiza / Q000737:chemistry; D006624:Hippocampus / Q000378:metabolism / Q000473:pathology; D002546:Ischemic Attack, Transient / Q000378:metabolism* / Q000473:pathology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D018696:Neuroprotective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D016716:PC12 Cells; D010946:Plants, Medicinal / Q000737:chemistry; D017966:Pyramidal Cells / Q000187:drug effects; D051381:Rats; D013482:Superoxide Dismutase / Q000378:metabolism*; D000072105:Superoxide Dismutase-1
D004365:Drugs, Chinese Herbal; D018696:Neuroprotective Agents; D007770:L-Lactate Dehydrogenase; C000606292:Sod1 protein, rat; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1