Solvent Fractionation and LC-MS Profiling, Antioxidant Properties, and α-Glucosidase Inhibitory Activity of Bombyx batryticatus

Abstract

Bombyx batryticatus is the dried body of silkworm (Bombyx mori Linnaeus) larvae infected with Beauveria bassiana. It is widely used in traditional Chinese medicine for treating convulsions, epilepsy, and hyperglycemia. In this study, Bombyx batryticatus and its extract were prepared. The total reducing power, hydroxyl radical scavenging and superoxide anion radical scavenging activities, as well as the α-glucosidase inhibitory activity of Bombyx batryticatus extract were superior to those of normal silkworm larvae extract. Among them, the IC₅₀ value of Bombyx batryticatus extract for α-glucosidase was 5.76 mg/mL, while that of normal silkworm larvae extract was 7.0 mg/mL. Untargeted metabolomic analysis was employed to compare the material composition of normal silkworm larvae and Bombyx batryticatus. The results revealed 101 metabolic differences between the two groups, including a significant increase in fatty acids and their derivatives in the Bombyx batryticatus extract. Further separation and purification of the Bombyx batryticatus extract were performed using solvents of varying polarity. The chloroform fraction exhibited the highest inhibitory activity against α-glucosidase, with an IC₅₀ value of 0.217 mg/mL. LC-MS further identified compounds in the chloroform fraction, suggesting that those alkaloids, fatty acids, and their derivatives may be responsible for its strong α-glucosidase inhibitory activity. This study elucidates the material basis underlying the pharmacological effects of Bombyx batryticatus, particularly its hypoglycemic components, thereby providing critical experimental support for its future development and application in medicine.

Keywords: ?-glucosidase inhibition; Beauveria bassiana; Bombyx batryticatus; antioxidant activity; composition analysis; extraction; metabolite profiling.

Figure 1

Disease symptoms and morphological changes in larvae infected with B. bassiana: (A) Body posture of silkworms 3 days after inoculation with B. bassiana. (B) Blastospores and hyphae of B. bassiana in the hemolymph of diseased larvae (×400). (C) Hemolymph of healthy larvae (×400). (D) Morphological changes in dead larvae. (E) Weight changes in dead larvae. Different lowercase letters (a–d) indicate significant differences among the means (p < 0.05).

Figure 2

Total reducing power (A), DPPH radical scavenging ability (B), hydroxyl radical scavenging ability (C), and superoxide anion radical scavenging ability (D) of B. batryticatus extract.

Figure 3

The inhibitory activities of B. batryticatus extract on α-glucosidase (A) and pancreatic lipase (B).

Figure 4

PCA scores plots (A1,B1) and OPLS-DA permutation test plots (A2,B2) in positive ion mode (A1,A2) and negative ion mode (B1,B2) between B. batryticatus and healthy larvae groups.

Figure 5

Total reducing power (A), DPPH radical scavenging activity (B), α-glucosidase inhibitory activity (C), and total flavonoid content (D) of the different fractions from B. batryticatus extract. Values marked by different letters (a, b, c) at the top of the bar chart are significantly different (p < 0.05).

Figure 6

Fractional extraction process of B. batryticatus.