Development of a novel and practical bioassay for the quality evaluation and control of Galli Gigerii Endothelium Corneum based on the detection of digestive enzyme activity / 药学学报

ABSTRACT

Galli Gigerii Endothelium Corneum (GGEC) represents digestion-promoting medicines with measurable effects and extensive clinical application. However, its effective components are not clear. The quality control index in the current edition of Chinese Pharmacopoeia is rather elementary and does not reflect its clinical efficacy. In this study, a bioassay method based on pepsin activity was proposed as a novel quality control method. With pepsin activity as the evaluation index, the extraction of GGEC was optimized and a method for the determination of biological potency was established by using the qualitative reaction parallel line method. The biological potency and consistency of 20 batches of GGEC were investigated. To provide scientific evidence in support of this bioassay method, two validation experiments were designed. One was to study the viscosity-reducing activity of a nutritional semi-solid paste after adding GGEC samples with differing potency. The other was to correlate the gastric residual rate in mice and pepsin activity with the alcohol soluble extract content. The results showed that the optimal preparation method was to dilute crude powder of GGEC with 50 volumes of water and subject to ultrasonic extraction at 300 W and 40 kHz for 0.5 h. The shape of the dose-response curve was similar to that of the positive control drug multienzyme tablets and the precision, intermediate precision and repeatability met the methodology requirements. The results showed that the potency of 20 batches of samples ranged from 13.49 to 34.69 U·mg-1, with an average value of 22.21 U·mg-1. The validation experiment demonstrated that the effect of reducing the viscosity of the nutrient paste became more significant as GGEC sample potency increased. The correlation coefficient R of gastric residual rate with pepsin potency and alcohol soluble extract content was 0.867 and 0.518, respectively, which indicated that the pepsin potency was highly correlated with in vivo activity. This study shows that a bioassay method based on pepsin activity is reliable and reproducible for GGEC and could provide reference method for the quality evaluation of other digestant herbs.