Analysis of proteins and peptides to investigate the molecular signatures of a conventional antidiabetic herb, Boerhavia procumbens Banks ex Roxb. (Nyctaginaceae)

Boerhavia procumbens Banks ex Roxb. (Nyctaginaceae) is a diuretic herb that is traditionally used to treat diabetes mellitus, a disease having an alarmingly high prevalence rate worldwide. Although various micro molecules present in B. procumbens are known for their antidiabetic roles, the macromolecular constituents have not been studied yet. The current study was therefore planned to identify and characterize the antidiabetic proteins/peptides, if any, present in B. procumbens. Initially the proteins/peptides were extracted, from roots and whole plant of B. procumbens, in sodium phosphate buffers each of concentration 200 mM and of variable pH (range 6-8). The crude extracts were primarily tested for their inhibitory potential against α-glucosidase and α-amylase. The crude extracts with significant inhibitory potential were processed for partial purification of proteins/peptides through the ammonium sulphate (NH₄)₂SO₄ precipitation method. The precipitated proteins/peptides were purified through dialysis, and purified fractions, followed by protein quantification, were tested for anti-α-glucosidase and anti-α-amylase activity. The proteins/peptides mixtures were resolved on SDS PAGE, and prominent gel bands were cut and subjected to LC-MS/MS. All crude extracts were found to strongly inhibit both enzymes (i.e., α-glucosidase and anti-α-amylase). Only 03 proteins/peptides fractions were inhibitory to α-glucosidase (with IC₅₀ range of 137.8 ± 1.2 µg/mL- 352.3 ± 1.2 µg/mL), while 09 fractions were active against α-amylase (with IC₅₀ range of 24.24 ± 1.8 µg/mL to 85.55 ± 4 µg/mL). A total of 20 proteins were identified via LC-MS/MS analysis, including 04 well-known antidiabetic proteins, i.e., γ-conglutin, thioredoxin peroxidase, 7S globulin, and Zerumbone synthase enzyme. Our study has provided reliable molecular evidence that assures the antidiabetic potential of B. procumbens and suggests the future extension of work for the purification, functional characterization and therapeutic application of antidiabetic proteins.