The Study of Anti-tetrodotoxin Effect of Thunbergia laurifolia Linn. crude Extract

Suwanna Cowawintaweewat, Srinuan Somroop, Onruedee Khantisitthiporn, Anek Pootong

Abstract


Tetrodotoxin is a potent heat stable neurotoxin with no known antidote. As the toxin blocks the Na+ channel, it can produce paralysis of the diaphragm and cause death due to respiratory failure. Recently, there was a report from a newspaper about a patient who exposed tetrodotoxin by ingestion, could recover from illness after drinking water-squash of Thunbergia laurifolia Linn. (Rang Chuet) which is a Thai herbal medicinal plant used as antidote for many toxic substances. However, there hasn’t been any study about the effect of Rang Chuet on tetrodotoxin. This study aimed to evaluated the anti-tetrodotoxin effect of Rang Chuet aqueous extract in ICR mice. The aqueous extract of Rang Chuet was prepared and tested for Acute Oral Toxicity using ICR mice with age of 5-6 weeks. Ten mice (5 male and 5 female) per group were orally administered with various doses of Rang Chuet extract. All doses of the extract: 500, 1,000 and 2,000 mg/kg bw, had no adverse effect on the liver as no change in the level of AST (p = 0.944, 0.859 and 0.575, respectively) and on survival with 0% of mortality rate. The Oral Median LD50 value was estimated in 10 male mice per groups with various doses of tetrodotoxin. The LD50 values were 619 and 700 μg/kg bw as determined by probit analysis and Reed & Muench method, respectively. The 100% of mortality rate was found in group of mice administered with 1,200 μg/kg bw of tetrodotoxin. In the study, the duplication of five male mice per groups were employed for evaluation of anti-tetrodotoxin effect of 2,000 mg/kg bw of Rang Chuet extract on 1,200 μg/kg bw of tetrodotoxin. The control groups were treated with distilled water instead of Rang Chuet extract in the same operation as the test groups. The survival time of mice in all groups administered with Rang Chuet extract at 0 min, 30 min, or 60 min before tetrodotoxin administration, were significantly longer than in the control groups (p = 0.000, 0.001 and 0.049, respectively). The survival rate of mice in groups administered with Rang Chuet extract simultaneously with, or 30 min before tetrodotoxin were 80% (8/10) and 30% (3/10), respectively. The results reveal that Rang Chuet aqueous extract may extend the survival time and survival rate of mouse administered with lethal dose of tetrodotoxin. However, this study could not conclude how Rang Chuet acted to reduce the toxicity of tetrodotoxin Its mechanism may affect the absorption rate, elimination rate of tetrodotoxin or directly neutralize. The further investigation and experimental design should be performed for study of its mechanism.

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