Novel Exopolysaccharide from Marine Bacillus subtilis with Broad Potential Biological Activities: Insights into Antioxidant, Anti-Inflammatory, Cytotoxicity, and Anti-Alzheimer Activity

Basel A Abdel-Wahab; Hanaa F Abd El-Kareem; Ahmad Alzamami; Cinderella A Fahmy; Basem H Elesawy; Maged Mostafa Mahmoud; Ahmed Ghareeb; Ahmad El Askary; Hebatallah H Abo Nahas; Nashwah G M Attallah; Najla Altwaijry; Essa M Saied

doi:10.3390/metabo12080715

Novel Exopolysaccharide from Marine Bacillus subtilis with Broad Potential Biological Activities: Insights into Antioxidant, Anti-Inflammatory, Cytotoxicity, and Anti-Alzheimer Activity

Metabolites. 2022 Jul 31;12(8):715. doi: 10.3390/metabo12080715.

Authors

Basel A Abdel-Wahab^{1

2}, Hanaa F Abd El-Kareem³, Ahmad Alzamami⁴, Cinderella A Fahmy^{5

6}, Basem H Elesawy⁷, Maged Mostafa Mahmoud^{8

9

10}, Ahmed Ghareeb¹¹, Ahmad El Askary¹², Hebatallah H Abo Nahas¹³, Nashwah G M Attallah¹⁴, Najla Altwaijry¹⁴, Essa M Saied^{15

16}

Affiliations

¹ Department of Medical Pharmacology, College of Medicine, Assiut University, Assiut 7111, Egypt.
² Department of Pharmacology, College of Pharmacy, Najran University, P.O. Box 1988, Najran 55461, Saudi Arabia.
³ Zoology Department, Faculty of Science, Ain Shams University, Abbasseya, Cairo 11566, Egypt.
⁴ Clinical Laboratory Science Department, College of Applied Medical Science, Shaqra University, P.O. Box 1383, Al Quwayiyah 11961, Saudi Arabia.
⁵ Cancer Biology and Genetics Laboratory, Centre of Excellence for Advanced Sciences, National Research Centre, Dokki, Cairo 12622, Egypt.
⁶ Biochemistry Department, National Research Centre, Dokki, Cairo 12622, Egypt.
⁷ Department of Pathology, College of Medicine, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
⁸ Cancer Biology Unit, King Fahd Medical Research Center, King Abdulaziz University, P.O. Box 80216, Jeddah 21589, Saudi Arabia.
⁹ Department of Medical Laboratory Sciences, Faculty of Applied Medical Sciences, King Abdulaziz University, P.O. Box 3646, Jeddah 22252, Saudi Arabia.
¹⁰ Department of Molecular Genetics and Enzymology, Human Genetics and Genome Research Institute, National Research Centre, Cairo 12622, Egypt.
¹¹ Botany and Microbiology Department, Faculty of Science, Cairo University, Giza 12613, Egypt.
¹² Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia.
¹³ Zoology Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt.
¹⁴ Department of Pharmaceutical Science, College of Pharmacy, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia.
¹⁵ Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt.
¹⁶ Institute for Chemistry, Humboldt Universität zu Berlin, Brook-Taylor-Str. 2, 12489 Berlin, Germany.

Abstract

In the presented study, Bacillus subtilis strain AG4 isolated from marine was identified based on morphological, physiological, phylogenetic characteristics and an examination of 16S rRNA sequences. Novel exopolysaccharide (EPSR4) was extracted and isolated from the Bacillus subtilis strain as a major fraction of exopolysaccharide (EPS). The analysis of structural characterization indicated that EPSR4 is a β-glycosidic sulphated heteropolysaccharide (48.2%) with a molecular weight (Mw) of 1.48 × 10⁴ g/mole and has no uronic acid. Analysis of monosaccharide content revealed that EPSR4 consists of glucose, rhamnose and arabinose monosaccharide in a molar ratio of 5:1:3, respectively. Morphological analysis revealed that EPSR4 possess a high crystallinity degree with a significant degree of porosity, and its aggregation and conformation in the lipid phase might have a significant impact on the bioactivity of EPSR4. The biological activity of EPSR4 was screened and evaluated by investigating its antioxidant, cytotoxicity, anti-inflammatory, and anti-Alzheimer activities. The antioxidant activity results showed that EPSR4 has 97.6% scavenging activity toward DPPH free radicals at 1500 µg/mL, with an IC₅₀ value of 300 µg/mL, and 64.8% at 1500 µg/mL toward hydrogen peroxide free radicals (IC₅₀ = 1500 µg/mL, 30 min). Furthermore, EPSR4 exhibited considerable inhibitory activity towards the proliferation of T-24 (bladder carcinoma), A-549 (lung cancer) and HepG-2 (hepatocellular carcinoma) cancer cell lines with IC₅₀ of 244 µg/mL, 148 µg/mL and 123 µg/mL, respectively. An evaluation of anti-inflammatory activity revealed that EPSR4 has potent lipoxygenase (LOX) inhibitory activity (IC₅₀ of 54.3 µg/mL) and a considerable effect on membrane stabilization (IC₅₀ = 112.2 ± 1.2 µg/mL), while it showed cyclooxygenase (COX2) inhibitory activity up to 125 µg/mL. Finally, EPSR4 showed considerable inhibitory activity towards acetylcholine esterase activity. Taken together, this study reveals that Bacillus subtilis strain AG4 could be considered as a potential natural source of novel EPS with potent biological activities that would be useful for the healthcare system.

Keywords: AFM analysis; Bacillus subtilis; FTIR; SEM analysis; X-ray diffraction; acetylcholine esterase activity; anti-inflammatory; antioxidant; cytotoxicity; exopolysaccharide; marine natural product; morphological analysis.

Grants and funding

This research was funded by Faculty of Science, Suez Canal University, Ismailia, Egypt. This research was also funded by Princess Nourah bint Abdulrahman University Researchers Supporting Project number (PNURSP2022R89), Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia. The authors also extend their appreciation to the fund supported by Taif University Researchers Supporting Project number (TURSP-2020/127), Taif University, Taif, Saudi Arabia.