Lactobacillus bulgaricus improves antioxidant capacity of black garlic in the prevention of gestational diabetes mellitus: a randomized control trial

Abstract

Objectives:Lactobacillus bulgaricus may improve antioxidant capacity of black garlic in the prevention of gestational diabetes mellitus (GDM).Methods: Black garlic was prepared with or without L. bulgaricus Volatile and polysaccharides were analyzed by using LC-MS, Fourier Transform infrared (FTIR) and ¹³C nuclear magnetic resonance (NMR). The study design was parallel randomized controlled trial and 226 GDM patients were randomly assigned into BG (black garlic and L. bulgaricus) and CG (black garlic) groups, and allocation ratio was 1:1. The treatment duration was 40 weeks. Fasting blood glucose (FBG) and 1- and 2-h blood glucose (1hBG and 2hBG) after oral glucose tolerance test (OGTT) were detected. Antioxidant function of black garlic was determined by measuring plasma malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and total antioxidant capacity (T-AOC) in GDM patients. The comparison between two groups was made using two independent samples t test.Results: The intake of nutrients was similar between two groups (P>0.05). L. bulgaricus promoted the transformation of the glucopyranoside to glucofuranoside. L. bulgaricus increased the abilities of black garlic for scavenging hydroxyl radicals, 2,2'-azino-bis (3-ethylbenzenthiazoline-6-sulfonic) acid (ABTS) and DPPH free radicals. L. bulgaricus reduced the levels of FBG, 1hBG and 2hBG, and incidence of perinatal complications (P<0.01). Plasma MDA level in the BG group was lower than in the CG group, whereas the levels of SOD, GSH-PX and T-AOC in the BG group were higher than in the CG group (P<0.01).Conclusions:L. bulgaricus improves antioxidant capacity of black garlic in the prevention of GDM.

Keywords: Lactobacillus bulgaricus; antioxidant capacity; black garlic; gestational diabetes; oral glucose tolerance test.

Figure 1. The flowchart of the present study

Figure 2. FITR analysis of the functional groups in the polysaccharide of garlic

(A) The polysaccharide in BG group before fermentation. (B) The polysaccharide in CG group before fermentation. (C) The polysaccharide in BG group after fermentation. (D) The polysaccharide in CG group after fermentation. FITR; Fourier Transform infrared.

Figure 3. ¹³C NMR analysis of the polysaccharide structure of garlic

(A) The polysaccharide in BG group before fermentation. (B) The polysaccharide in CG group before fermentation. (C) The polysaccharide in BG group after fermentation. (D) The polysaccharide in CG group after fermentation.

Figure 4. The comparison of antioxidant capacity

(A) The reducing ability of polysaccharide among BG, CG and Vc groups before fermentation. (B) The reducing ability of polysaccharide among BG, CG and Vc groups after fermentation. (C) The T-AOC of polysaccharide among BG, CG and Vc groups before fermentation. (D) T-AOC of polysaccharide among BG, CG and Vc groups after fermentation. (E) The hydroxyl radical scavenging ability of polysaccharide among BG, CG and Vc groups before fermentation. (F) Hydroxyl radical scavenging ability of polysaccharide among BG, CG and Vc groups after fermentation. (G) ABTS free radical scavenging ability of polysaccharide among BG, CG and Vc groups before fermentation. (H) ABTS free radical scavenging ability of polysaccharide among BG, CG and Vc groups after fermentation. (I) DPPH free radical scavenging ability of polysaccharide among BG, CG and Vc groups before fermentation. (J) DPPH free radical scavenging ability of polysaccharide among BG, CG and Vc groups after fermentation. *P<0.05 vs. a control group.