Cell experiment:

Pancreatic β-cells are treated with 1, 10, 100 μM of allantoin before 30 min prior to the addition of 5 mM STZ and incubated for 6 h. Cell viability is measured using the ApoTox-Glo triplex assay[2].

Animal experiment:

Rats: Animals are randomly assigned into four groups: (I) the control group treated with the vehicle, saline; (II) the allantoin group treated by intravenous injection of allantoin at 0.5 mg/kg; (III) the allantoin+efaroxan group treated with allantoin at the most effective dose (0.5 mg/kg, i.v.) and efaroxan at effective dose (1.5 mg/kg, i.v.) 30 minutes before injection of allantoin; and (IV) the allantoin treated SHRs group treated by intravenous injection of allantoin at various dose for desired time. After treatment of allantoin, the rats are placed into a holder for the determination of the mean blood pressure[3]. Mice: For memory ameliorating study, mice are administered vehicle solution, allantoin (1, 3 or 10 mg/kg, p.o.) or donepezil (5 mg/kg, p.o.) at the same time (10:00-12:00 a.m) and same place for 7 days. For memory enhancing study, mice are administered vehicle solution, allantoin (1, 3 or 10 mg/kg, p.o.) or piracetam (200 mg/kg, i.p.). The final administration of allantoin, donepezil or piracetam is performed 1 h before an acquisition trial in the passive avoidance task[1].

Allantoin is a skin conditioning agent that promotes healthy skin, stimulates new and healthy tissue growth.

Allantoin is a well-known cosmetic ingredient reported to have anti-oxidative and anti-inflammatory activities[1]. Allantoin attenuates apoptosis and cytotoxicity and increased the viability of STZ-induced β-cells in a dose-dependent manner. Allantoin decreases the level of caspase-3 and increases the level of phosphorylated B-cell lymphoma 2 (Bcl-2) expression. Allantoin has been demonstrated to activate imidazoline 3 (I3) receptors[2].

The subchronic administration of allantoin (1, 3 or 10 mg/kg, for 7 days) significantly increases the latency time measured during the passive avoidance task in scopolamine-induced cholinergic blockade and normal naive mice. Allantoin treatment (3 or 10 mg/kg, for 7 days) also increases the expression levels of phosphorylated phosphatidylinositide 3-kinase (PI3K), phosphorylated protein kinase B (Akt) and phosphorylated glycogen synthase kinase-3β (GSK-3β). Allantoin significantly increases the neuronal cell proliferation of immature neurons in the hippocampal dentate gyrus region[1]. Daily injection of allantoin for 8 days in STZ-treated rats significantly lowers plasma glucose and increases plasma insulin levels [2]. Allantoin decreases blood pressures in SHRs at 30 minutes, as the most effective time. Also, this antihypertensive action is shown in a dose-dependent manner from SHRs treated with allantoin. Moreover, in anesthetized rats, allantoin inhibits cardiac contractility and heart rate. Also, the peripheral blood flow is markedly increased by allantoin[3].

References:
[1]. Ahn YJ, et al. Effects of allantoin on cognitive function and hippocampal neurogenesis. Food Chem Toxicol. 2014 Feb;64:210-6.
[2]. Amitani M, et al. Allantoin ameliorates chemically-induced pancreatic β-cell damage through activation of the imidazoline I3 receptors. PeerJ. 2015 Aug 6;3:e1105.
[3]. Chen MF, et al. Antihypertensive action of allantoin in animals. Biomed Res Int. 2014;2014:690135.