Martin-Luther O Okolo1,
Sunday A Adegoke1,
David A Zakari1,
Kizito E Bello1,
Cornelius A Omatola1,2 
For correspondence:- Cornelius Omatola Email: omatolac@gmail.com Tel:+234-8061259317
Received: 21 October 2024 Accepted: 30 December 2024 Published: 28 January 2025
Citation: Okolo MO, Adegoke SA, Zakari DA, Bello KE, Omatola CA. Isolation and characterization of terrestrial Streptomyces strains with antimicrobial and anti-ulcer activities. Trop J Pharm Res 2025; 24(1):85-96 doi: 10.4314/tjpr.v24i1.12
© 2025 The authors.
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Purpose: To determine the antimicrobial, anti-ulcer and cytotoxic activities of secondary metabolites isolated from Streptomyces spp in soil samples obtained from Anyigba, Kogi State, Nigeria. Methods: The cytotoxic activity of Streptomyces secondary metabolites (concentration range: 62.5 – 1000 mg/mL) was assessed using brine shrimp lethality assay on different concentrations (62.5, 125, 250, 500, 1000 mg/mL) of the secondary metabolites or the reference K2Cr2O7. The anti-ulcer activity was evaluated using aspirin and ethanol models of ulcers in albino rats. Five groups of animals viz three pretreated groups with the extracts at two different oral concentrations of 100 and 200 mg/kg, one pretreated group with omeprazole (30 mg/kg) as standard and another group with oral 2 mL/kg normal saline (control). Antibacterial and antifungal activities were investigated using the microdilution method. Results: Cytotoxicity test showed that extract concentrations of 12.5 to 62.5 mg/mL exerted mild toxicity compared to control. For antiulcer activity, animals in group 1 showed mucosal infiltration of leucocytes, massive exfoliation of epithelial cells and cellular hemorrhage while group 2 had mild tissue erosion and small ulcer. In groups 3 to 5, extract at 200 mg/kg showed excellent cytoprotection and proficient curative capacity in contrast to the 100 mg/kg, without significant side effects while the standard group showed some side effects and a significant reduction in the mucus cells (p < 0.05). The secondary metabolites inhibited ulcer-implicated organisms (Helicobacter pylori, Escherichia coli, Campylobacter spp and Streptococcus spp), exerted curative effect and protected the rats from ulcers. Conclusion: Secondary metabolites isolated from Streptomyces spp were not toxic to epithelial tissue and exhibit antimicrobial and anti-ulcer activities and thus has potential as an important source of drugs against peptic ulcers.
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