Production of exopolysaccharides from novel marine bacteria and anticancer activity against hepatocellular carcinoma cells (HepG2)

Abstract

Background: The aim of the current study based on the production and characterization of exopolysaccharides (EPSs) isolated from marine sediment of the Mediterranean and Red Seas is to study its cytotoxic activity against HepG2 cells. Results: Eleven isolates have the ability to produce EPSs and also decreased the viability of HepG2 cell line in different manners. The five most promising isolates that produce high yield of EPSs and high cytotoxicity were identified by 16S RNA as Brevundimonas subvibrioides MSA1, Bacillus thuringiensis E4, Bacillus amyloliquefaciens MGA2, Pseudomonas fluorescens SGA3, and Advenella Kashmirensis NRC-7. The chemical composition of the following EPSs (M1, M3, M6, M15, M19, E2, E4, E10, S5, S7, and S11) demonstrates that they are acidic sulfated heteropolysaccharides with different relative ratios of monosugars of glucose, mannose, galactose, glucouronic acid, and mannouronic acid. The average molecular weights from 1.94 × 10 4 to 7.95 × 10 5 g/mol and the number average molecular weight from 1.51 × 10 4 to 7.53 × 10 5 g/mol. FTIR spectrum of the five EPSs indicated the presence of sulfate and carboxylic groups in different percentages. Conclusions: The EPSs produced from marine bacteria are very promising for treating the HepG2 cells.

Advances in exopolysaccharide production from marine bacteria

“…In general, the molecular weight of the EPS synthesized by marine bacteria usually ranges from 100 to 500 kDa 60 . As it has been previously described, these polymers contain different relative ratios of monosaccharides of Glc, Man, Gal, GlcA, and GalA coordinated in a range of around 10 to compose repeating units 61 . Regarding polydispersity index (PDI), it has been reported that a low (between 1.0–1.5) PDI can be observed: this value is used as a measure of the broadness of the molecular weight distribution of a polymer.…”

“…and Pseudomonas sp., have shown antitumor activity that is of medical interest 15,29,105,108 . For instance, Asker et al 61 . isolated several marine bacteria that produced EPS and decreased the viability of HepG2 cells in different manners when different concentrations of EPS were evaluated (125–1000 μg/mL).…”

“…Finally, the EPS from the marine bacteria Flavobacterium uliginosus MP‐55 (marinactan) showed an antitumoral activity against sarcoma 180 in both solid and ascites forms 15 . All these findings have motivated the development of new anticancer drugs for the treatment of several types of cancer 1,15,61,107 …”

“…Marine EPS exhibit antioxidant activity that can prevent different diseases, inflammation, and atherosclerosis 109 . Marine EPS from halophilic strains of the genus Halomonas have shown antioxidant activity; for instance, the EPS of H. xianhensis SUR308 showed a 43% to 72% DPPH radical scavenging activity at low concentrations 61 . According to their antimicrobial activity, marine EPS have shown microbial inhibition against Gram‐positive and Gram‐negative bacteria, such as the genera Lysinibacillus, Paenibacillus, Pseudomonas, and Escherichia , among others 109 .…”

Production of water‐soluble sulfated exopolysaccharide with anticancer activity from Anoxybacillus gonensisYK25

“…Therefore, it can be deduced that the presence of xylose and galactose monomers is the first reason for the anticancer activity of the produced EPS. Another possible reason is the presence of sulphate groups in EPS, since it has been reported that sulphate groups increase the anticancer activity of polysaccharides 52,67,68 …”