Benzoinum Medicinal Material Quality Analysis And Pharmacokinetic Studies Of Benzoic Acid In Rats

Benzoinum is pungent and bitter in flavour; warm in property; acting on the heart, spleen, lung, and stomach channels. It is frequently used for inducing resuscitation, removing the pathogens of fetid odour, promoting blood circulation of qi, eliminating phlegm, and arresting cough. Benzoinum specified in the Chinese Pharmacopoeia 2010 edition(VolⅠ) is the dry resin of Styrax tonkinensis (Pierre) Craib ex Hart. There are two benzoinum species in the market, one is the species specified in the Chinese Pharmacopoeia, the other is Benzolinum Styracis Benzoinis. In recent years, 55 Styracaceae species in southeast to southwest of yunnan, which were considered as new resources of benzoinum.Objective:To compare the content of cinnamic acid and benzoic acid in benzoinum from different regions; and, to make some preliminary discussion on the the pharmacokinetic process of benzoic acid in rat in vivo.Methods:Ten batches of benzoinum from three regions-Sumatra, Thailand, and China were determined by HPLC in order to find new resources of benzoinum. The content of benzoic acid in rat plasma, brain, liver, heart, spleen, lung, kidney were determined to research the connection between the channel tropism and the therapeutic basis of benzoinum.Results:①The content of Cinnamic acid in benzoinum ranged between 0.047% and 0.103%. the average content decreased in sequence of Sumatra benzoinum (0.082%)>Thailand benzoinum>(0.079%) Chinese benzoinum (0.062%).The content of four batches benzoinum from Thailand vary greatly from one to another, while there was little variance in content from Sumatra and China. Statistical evaluation indicated that there was no significant difference in the content of Cinnamic acid among these three regions (P>0.05). The content of benzoic acid was in the range of 25.28% to 32.02%,the average contents in Chinese benzoinum, Thailand benzoinum, Sumatra benzoinum were 31.33%,28.14%,27.88%, respectively. Besides, Sample 3,4,8 didn't meet the standard (more than 27%) specified in the Chinese Pharmacopoeia. However, statistical evaluation revealed that there was no significant difference in the content of benzoic acid among this three regions (P>0.05).②An RP-HPLC method for the determinatione of benzoic acid in rat plasma was stablished. The content of benzoic acid in the range of 0.05 to 204.8μg·mL-1,had a good linear correlation with signal response (r=0.99995). The relative standard deviations (RSD) of the intra-day precision was less than 4.38%, and the value of the between-day precision was less than 3.48%, RSD of stability within 5 days was less than 3%, and the range of recovery was 96.05% to 104.05%.8 rats were given a single dose of 20 mL·kg-1 benzoinum by intragastric administration and the blood Was obtained at different time points after the administration. The content of benzoic acid in rat plasma was determined by HPLC to establish a concentration-time curve and obtain the pharmacokinetic parameters:Cmax =0.0558±0.0508 mg·mL-1,tmax=1±0h, t1/2=0.168±0.0845 h, AUC(0～∞=0.0763±0.0767 h·mg·mL-1 for female;Cmax=0.0774±0.0369 mg·mL-1, tmax=1±0h, t1/2= 0.533±0.4174 h,AUC(0～∞)=0.1154±0.0581 h·mg·mL-1 for male.70 minuts after intragastric administration, the plasma, livers, hearts, spleens, lungs, kidneys and brains of rats were removed and extracted with methanol-acetonitrile (1:1), then, was determine using HPLC. The results showed that benzoic acid existed in all of the samples above which revealed that benzoic acid can reach all of the tissue above.Conclusion:This study explored the content determination method, the pharmacokinetic parameters and the distribution of benzoic acid in rat in vivo. The results of pharmacokinetic experiments explained the theory of "benzoinum acting on the heart, spleen, lung, and stomach channels". In addition, it also showed that this drug can get through the blood-brain barrier (BBB) and played the role of inducing resuscitation.