Distinctive quality control method for solid-state fermented Isaria cicadae from strain Ic-17-7 and application in type 2 diabetes rat model

This work aims to establish a quality control method and evaluate the effects in glucose and lipids for fruit body of Isaria cicadae Miquel from strain Ic-17-7(Ic-17-7fb) in type 2 diabetes (T2DM) rat model. Random amplified polymorphic DNA, sequence-characterized amplified region, and high-performance liquid chromatography (HPLC) were used for the quality control of Ic-17-7fb. The pharmacological effects on streptozocin (STZ)-induced high-fat diet-fed Albino Wistar rats, divided into model, metformin, fruiting body of Ic-17-7fb (0.166 g/kg and 0.5 g/kg) and control group were evaluated. The fasting blood glucose (FBG), blood glucose, total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL-c), and low-density lipoprotein (LDL-c) were measured. The Ic-17-7fb could amplified a single specific band by S11-2-F3 and S11-2-R3 primers to validate. An HPLC-based quality and quantity was established and used for industrial application. The content of adenosine and N6-(2-hydroxyethyl) adenosine (HEA) of the cultivated Ic-17-7fb were analyzed. All of the validation lots of cultured Ic-17-7fb passed the quantity control of the training set (0.90 mg/g of adenosine and 0.89 mg/g of HEA). The average FBG in the 2ed -week were 4.89 ± 0.42 (control), 26.10 ± 5.77 (model), 23.63 ± 6.15 (metformin), 17.96 ± 9.36 (Ic-17-7fb for 0.166 g/kg), and 19.69 ± 8.71 mmol/L (Ic-17-7fb for 0.5 g/kg). The fruit body of Ic-17-7 (0.166 g/kg) treatment significantly was reduced by 31.19% compared with the model in the 2ed-week (p < 0.01). Ic-17-7fb (0.166 g/kg) significantly decreased the fasting blood glucose after 2 weeks of administration. Metformin, Ic-17-7fb (0.166 g/kg), and Ic-17-7fb (0.5 g/kg) reduced the TC, TG, HDL-c, and LDL-c compared with the T2DM model treatment at the 6th week of treatment (p < 0.05). This study established the first quality standard for Ic-17-7fb and has an effective application in the treatment of T2DM. The reliable method and pharmacological effect can be generalized to a broader population and possibility study for future research.