Efficacy of Endophytic Bacterium Serratia marcescens B.SB 1.1 associated with Sea Fern (Acrostichum aureum L.) as an Antidiabetic Agent

Abstract

Diabetes mellitus (DM) is a primary global health concern, often progressing unnoticed until complications arise. Current antidiabetic therapies primarily aim to inhibit the α-amylase enzyme, thereby reducing blood glucose levels. Some medicinal plants are proven to be symbiotic with endophytic bacteria that produce bioactive compounds capable of inhibiting α-amylase activity. This study investigated the potential of endophytic bacteria isolated from the stem of the sea fern (Acrostichum aureum L.) to act as α-amylase inhibitors, using both in vitro and in silico studies. Phytochemical analysis of both the stem extract and cultured bacterial isolates showed the presence of alkaloids, flavonoids, and saponins. Isolate B.SB 1.1 was identified as Serratia marcescens based on 16S rRNA sequencing. The α-amylase inhibition assay demonstrated the strain as showing significant inhibitory activity, with 32.57% inhibition at 2% starch substrate concentration. In silico docking studies using LC-MS data predicted 4-propylbiphenyl and benzoin as compounds with the lowest binding energy to α-amylase, suggesting their potential as effective inhibitors. These findings highlight the efficacy and therapeutic potential of endophytic strain S. marcescens B.SB 1.1 as a novel antidiabetic agent.

Keywords: Acrostichum aureum L.; endophytic bacteria; phytochemicals; α-amylase inhibitors.

Fig. 1. Isolate B.SB 1.1 of endophytic bacteria from sea fern stem (A. aureum L.).

(A) Morphology of colony which shows the elevation and the edges of colony. (B) Gram staining of colony shows purplish-red color.

Fig. 2. Phylogenetic tree based on the analysis of partial 16S rRNA gene sequences from isolate B.SB 1.1 that was constructed using reference sequences of Serratia from the NCBI database.

Phylogenetic tree show isolate B.SB 1.1 closest to Serratia marcescens.

Fig. 3. Chemical structures of the compounds B.SB 1.1.

(A) 4-Propylbiphenyl and (B) Benzoin.

Fig. 4. Interactions the compounds with α-amylase enzyme.

(A) The interaction of 4-Propylbiphenyl-BSB10 with α-amylase shows hydrophobic interaction; (B) The interaction of Benzoin-BSB8 with with α-amylase show hydrogen-bonded interaction and hydrophobic interaction; (C) The interaction of Acarbose (Native ligand) with α-amylase show only hydrogenbonded interaction.