Genotoxicity studies on the root extract of Polygala tenuifolia Willdenow.

The root of Polygala tenuifolia Willdenow has been used for the treatment against insomnia, amnesia, depression, palpitations with anxiety, and memory improvement. However, there is no sufficient background information on toxicological evaluation of the root to given an assurance of safety for developing dietary supplements and functional foods. As part of a safety evaluation, the potential genotoxicity of the root extract of P. tenuifolia was evaluated using a standard battery of tests (bacterial reverse mutation assay, chromosomal aberrations assay, and mouse micronucleus assay). In a reverse mutation assay using four Salmonella typhimurium strains and Escherichia coli, the extract did not increase the number of revertant colonies in any tester strain with or without metabolic activation by S9 mix, and did not cause chromosomal aberration in short-period test with the S9 mix or in the continuous (24h) test. A bone marrow micronucleus test in ICR mice dosed by oral gavage at doses up to 2000 mg/kg/day showed no significant or dose dependent increase in the frequency of micronucleated polychromatic erythrocytes (PCE). These results indicate that ingesting the rot extract P. tenuifolia is not genotoxic at the proper dose.

BT-11 improves stress-induced memory impairments through increment of glucose utilization and total neural cell adhesion molecule levels in rat brains.

In Oriental medicine, roots of Polygala tenuifolia Willdenow have been known to be an important herb that exhibits sedative effects in insomnia, palpitation with anxiety, restlessness, and disorientation in humans. We previously reported that BT-11, extracted from those roots, improved scopolamine-induced amnesia in rats and inhibited acetylcholinesterase activities in vitro. Therefore, we proposed that BT-11 could remedy stress-induced memory deficits in rats. In this study, the stress-induced memory impairments in rats were significantly reversed almost to the control level by BT-11 treatment. To seek an active component of BT-11 that plays an important role in antipsychotic effects, we compared BT-11 with 3,4,5-trimethoxycinnamic acid (TMCA), which is a constituent of those root extracts. However, the effects of TMCA were less or were not consistent with those of BT-11 in some of tests. In particular, BT-11 reversed the stress-induced reduction of glucose utilization by [(18)fluorodeoxyglucose]FDG-PET and the levels of neural cell adhesion molecule (NCAM) in rat brains to the control levels, whereas TMCA did not. Therefore, BT-11 improved stress-induced memory impairments through increment of glucose utilization and total NCAM levels in rat brains. In conclusion, BT-11 may be strongly effective against stress-induced amnesia in rats, through the combined effects of TMCA and other active components of BT-11.

Preclinical Safety of the Root Extract of Polygala tenuifolia Willdenow in Sprague-Dawley Rats and Beagle Dogs.

The root of Polygala tenuifolia Willdenow has been used for the treatment of insomnia, depression, and amnesia. However, the toxicological properties of the herb have been overlooked, because it has been used for a long time for various purposes. In this study, we evaluated the preclinical safety of the root extract in rats and beagle dogs. First, the acute oral toxicity was tested in both rats and dogs. In the rats, only one female of 2 g/kg died, but no treatment-related death or clinical and gross findings were observed after the administration. No toxicological changes or mortalities related to the test substance were also observed after the administration in the dogs. Although vomiting, discoloration, or hemorrhage was found in some dogs, there were no serious abnormalities. Second, the subchronic toxicity was investigated in the rats. Two animals were found dead in the female group of 1,000 mg/kg/day, but there were no abnormal findings associated with the test substance. There also were no adverse effects on the clinical signs, body weight, and hematological and biochemical findings. Therefore, our results showed that the acute or subchronic toxicity of the root extract of Polygala tenuifolia might not be toxic to rats and dogs.

A novel compound, maltolyl p-coumarate, attenuates cognitive deficits and shows neuroprotective effects in vitro and in vivo dementia models.

To develop a novel and effective drug that could enhance cognitive function and neuroprotection, we newly synthesized maltolyl p-coumarate by the esterification of maltol and p-coumaric acid. In the present study, we investigated whether maltolyl p-coumarate could improve cognitive decline in scopolamine-injected rats and in amyloid beta peptide(1-42)-infused rats. Maltolyl p-coumarate was found to attenuate cognitive deficits in both rat models using passive avoidance test and to reduce apoptotic cell death observed in the hippocampus of the amyloid beta peptide(1-42)-infused rats. We also examined the neuroprotective effects of maltolyl p-coumarate in vitro using SH-SY5Y cells. Cells were pretreated with maltolyl p-coumarate, before exposed to amyloid beta peptide(1-42), glutamate or H2O2. We found that maltolyl p-coumarate significantly decreased apoptotic cell death and reduced reactive oxygen species, cytochrome c release, and caspase 3 activation. Taking these in vitro and in vivo results together, our study suggests that maltolyl p-coumarate is a potentially effective candidate against Alzheimer's disease that is characterized by wide spread neuronal death and progressive decline of cognitive function.