Ameliorative and Antioxidative Potential of Lactobacillus plantarum-Fermented Oat (Avena sativa) and Fermented Oat Supplemented with Sidr Honey against Streptozotocin-Induced Type 2 Diabetes in Rats

Abstract

The ameliorative and antioxidative stress effects of probiotic-enriched fermented oat (FOE) or fermented oat with honey (HFOE) extracts on streptozotocin-induced diabetes in rats were examined. The total phenolic content (TPC) and antioxidant activity (AOA) were increased in FOE and HFOE after 72 h of fermentation, and γ-aminobutyric acid (GABA) reached 7.35 mg 100 g^-1 in FOE and 8.49 mg 100 g^-1 in HFOE. The β-glucan levels were slightly decreased to 2.45 g 100 g^-1 DW in FOE and 2.63 g 100 g^-1 DW in HFOE. The antidiabetic and hypolipidemic properties of FOE and HFOE were studied in a designed animal model with seven treated groups for 6 weeks. Groups were treated as follows: group 1 (negative group, NR) and group 2 (diabetic rats, DR) were administered 7 mL distilled water orally per day; group 3 (DR + MET) rats were orally administered 50 mg standard drug Metformin kg^-1 daily; group 4 (DR + FOE1) diabetic rats were orally administered 3.5 mL FOE daily; group 5 (DR + FOE2) rats were orally administered 7 mL FOE daily; group 6 (DR + HFOE1) rats were orally administered 3.5 mL HFOE daily; and group 7 (DR + HFOE2) rats were orally administered 7 mL HFOE daily. The HFOE at the high dose had a synergistic effect, lowering random blood glucose (RBG) and fasting blood glucose (FBG). The hypolipidemic potential of HFOE at the high dose was indicated by significant reductions in triglycerides (TG), total cholesterol (CHO), high- and low-density lipoproteins (HDL and LDL), and very-low-density lipoproteins (VLDL). In addition, 7 mL of HFOE improved liver and kidney function more effectively than other fermented extracts or Metformin. As well as the antioxidant enzyme activity, reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD), and malonaldehyde (MDA) were significantly enhanced after the administration of HFOE at 7 mL by 68.6%, 71.5%, 55.69%, and 15.98%, respectively, compared to the DR group. In conclusion, administration of L. plantarum-fermented oats supplemented with honey demonstrated antidiabetic effects and a potential approach for controlling glucose levels and lipid profiles, and protecting against oxidative stress.

Keywords: Avena sativa; Lactobacillus plantarum; antidiabetic effects; fermented oats; honey.

Figure 1

Viability of L. plantarum (Log CFU mL⁻¹) and pH value during fermentation (mean ± SE), n = 3. LP, L. plantarum count in plain media; LP + H, L. plantarum count in media with 2% Sidr honey; pH-LP, pH value of basic media during L. plantarum fermentation; pH-LP + H, pH value of media with honey during L. plantarum fermentation. ^a–c Bars or lines during the fermentation period not sharing similar letters are significantly different (p > 0.05). ^A,B Bars or lines of each treatment not sharing similar letters during the fermentation time are significantly different (p > 0.05).

Figure 2

Effect of orally administrated FOE and HFOE on antioxidant biomarkers in streptozotocin-induced diabetes in rats (mean ± SE), n = 8. Experimental groups, see materials and methods; Section 2.8. GSH, reduced glutathione; MDA, malondialdehyde; SOD, superoxide dismutase; CAT, catalase. ^a–d Bars not sharing similar letters are significantly different (p > 0.05).

Figure 2

Effect of orally administrated FOE and HFOE on antioxidant biomarkers in streptozotocin-induced diabetes in rats (mean ± SE), n = 8. Experimental groups, see materials and methods; Section 2.8. GSH, reduced glutathione; MDA, malondialdehyde; SOD, superoxide dismutase; CAT, catalase. ^a–d Bars not sharing similar letters are significantly different (p > 0.05).