Polygalasaponin XXXII, a triterpenoid saponin from Polygalae Radix, attenuates scopolamine-induced cognitive impairments in mice

Abstract

Aim: Recent studies show that the extract of a Chinese herb Polygalae Radix exerts cognition-enhancing actions in rats and humans. The aim of this study was to characterize the pharmacological profiles of active compounds extracted from Polygalae Radix. Methods: Two fractions P3 and P6 and two compounds PTM-15 and polygalasaponin XXXII (PGS32) were prepared. Neuroprotective effects were evaluated in primary cortical neurons exposed to high concentration glutamate, serum deficiency or H 2 O 2 . Anti-dementia actions were assessed in scopolamine-induced amnesia in mice using step-through avoidance tests and channel water maze tests. After conducting the channel water maze tests, TrkB phosphorylation in mouse hippocampus was detected using Western blotting. Long-term potentiation (LTP) was induced in the dentate gyrus in adult rats; PGS32 (5 μL 400 μmol/L) was injected into the lateral cerebral ventricle 20 min after high frequency stimulation (HFS). Results: Compared to the fraction P6, the fraction P3 showed more prominent neuroprotective effects in vitro and cognitionenhancing effects in scopolamine-induced amnesia in mice. One active compound PGS32 in the fraction P3 exerted potent cognitionenhancing action: oral administration of PGS32 (0.125 mg· kg -1 ·d -1 ) for 19 days abolished scopolamine-induced memory impairment in mice. Furthermore, PGS32 (0.5 and 2 mg· kg -1 ·d -1 ) significantly stimulated the phosphorylation of TrkB in the hippocampus. Intracerebroventricular injection of PGS32 significantly enhanced HFS-induced LTP in the dentate gyrus of rats. Conclusion: PGS32 attenuates scopolamine-induced cognitive impairments in mice, suggesting that it has a potential for the treatment of cognitive dysfunction and dementia.

Polygalae radix extract ameliorates behavioral and neuromorphological abnormalities in chronic corticosterone‐treated mice

“…PRE did not recover spatial memory dysfunction, in contrast to previous studies . This inconsistency may be due to differences in the animal models used.…”

“…Li et al . described ameliorative effects of an ingredient of Polygalae radix on cognitive impairment in a transgenic Alzheimer disease model , and the four other aforementioned studies showed that ingredients or extracts of Polygalae radix improved scopolamine‐induced cognitive impairment . In contrast, in the current study, effects on cognitive impairment were examined in a CORT‐treated model.…”

“…Polygalae radix, the dried root of Polygala tenuifolia Willd., is a traditional herbal medicine used as a tranquillizer and anti‐amnesia drug in East Asia, including in China and Japan. In preclinical studies the extract or ingredients of Polygalae radix had antidepressant‐like and anti‐amnesia effects . In this study, the mechanisms of the ameliorative effects of Polygalae radix extract (PRE) on brain dysfunction were examined based on the effects of PRE on behavioral, neuromorphological and neurophysiological abnormalities in mice treated chronically with CORT.…”

Ethanol Extract of Oldenlandia diffusa Herba Attenuates Scopolamine-Induced Cognitive Impairments in Mice via Activation of BDNF, P-CREB and Inhibition of Acetylcholinesterase

“…However, there is no effective treatment available to cure this dreadful disease. Though recent some extracts/compounds of plants were reported to anti-amnestic efficacies [ 34 , 35 ], effective anti-amnestic agents have not been discovered yet.…”

Differences in Neuritogenic Activity and Signaling Activation of Madecassoside, Asiaticoside, and Their Aglycones in Neuro-2a cells

“…Moreover, the increments of both neurite-bearing cells and neurite length were notably subdued in MS-and AS-treated cells when ERK1/2 was inhibited. Several reports have suggested the possibility of triterpenoid and steroidal glycosides activating TrkA receptor and subsequently stimulating ERK1/2 signal transduction in neuronal cells [28][29][30].…”