Interaction of Scutellaria-Coptis herb pair in improvement of glucose and lipid metabolism of type 2 diabetes rats based on response surface method

The response surface method was used to evaluate the concentration range, property and degree of Scutellaria (HQ) and Coptis (HL) herb pair on improvement of glucose and lipid metabolism in this paper. Type 2 diabetes mellitus (T2DM) was induced in rats by low a dose of streptozotocin (STZ) in combination with high-fat diet feeding. The rats were administered with HQ-HL extract pairs at different ratio (1:0, 3:1, 2:1, 3:2, 1:1, 2:3, 1:2, 1:3, 0:1). To investigate the influence of herb pair extracts on glucose and lipid metabolism of T2DM rats, the multi index synthetic index method was adopted to integrate the indexes, then the response surface method was applied to analyze the integration results. The ratio of HQ and HL from 3:1 to 1:3 showed a synergistic effect (with the value between -0.2 and -0.8). Especially, when the proportion was between 3:2 and 1:3, herb pair extracts possessed stronger synergistic effects (value:-0.8). The high dose of HQ-HL with the ratio of 1:1 exhibited the strongest synergistic effect.