Benzimidazole Hydrone Derivatives Show Strong Gastroprotective Potential

Researchers have identified a novel series of benzimidazole-based hydrazone derivatives that demonstrate significant gastroprotective activity in an ethanol-induced gastric ulcer rat model. The study, which integrates multistep chemical synthesis, in vivo biological evaluation, histopathological examination, and oxidative stress biomarker profiling, highlights the potential of these hybrid molecules as candidates for future anti-ulcer therapeutics. Among the eleven synthesized compounds, designated SH1 through SH11, the derivative SH1 exhibited the most potent protective effects, achieving a gastric lesion inhibition rate of 79.51%, a figure closely comparable to the reference drug omeprazole, which achieved 82.79% inhibition.

Peptic ulcer disease remains a prevalent gastrointestinal disorder, affecting an estimated 5–20% of the global population and placing a substantial burden on healthcare systems. The pathogenesis of gastric ulcers involves a complex imbalance between aggressive factors, such as Helicobacter pylori infection, non-steroidal anti-inflammatory drugs, alcohol, and oxidative stress, and the protective mechanisms of the gastric mucosa. While current treatments like proton pump inhibitors have improved clinical outcomes, their prolonged use is associated with adverse effects, bacterial resistance, and ulcer recurrence. Consequently, there is a persistent need for safer and more effective agents that can address multiple aspects of gastric injury, including inflammation and oxidative damage.

The benzimidazole scaffold is a privileged structure in medicinal chemistry, known for its structural versatility and wide range of biological activities. It is a key component in clinically approved proton pump inhibitors such as omeprazole and esomeprazole, which function as prodrugs activated in the acidic environment of gastric parietal cells. Beyond its role in acid suppression, the benzimidazole nucleus possesses intrinsic antioxidant and cytoprotective properties. By fusing this scaffold with the acetohydrazide moiety, researchers aimed to create hybrid molecules that could not only mitigate gastric injury but also bolster endogenous antioxidant defenses, thereby addressing the multifactorial nature of ethanol-induced mucosal damage.

The synthesis of the eleven derivatives was achieved through a five-step strategy starting from 4-hydroxybenzaldehyde. The process involved the formation of a benzimidazole core, esterification, hydrazinolysis to form the key acetohydrazide intermediate, and final condensation with various aromatic and heteroaromatic aldehydes to generate the Schiff base derivatives. The compounds were characterized using Fourier-transform infrared spectroscopy, proton and carbon-13 nuclear magnetic resonance spectroscopy, and melting point determination. This systematic approach allowed for the precise control of the aldehyde-derived substituents, enabling a detailed structure-activity relationship analysis to correlate structural features with biological efficacy.

In the in vivo evaluation, healthy adult male albino rats were subjected to an acute ethanol-induced gastric ulcer model. The animals were randomly allocated into fourteen groups, including a normal control, an ulcer control, an omeprazole-treated group, and eleven groups receiving the synthesized compounds. The compounds were administered orally at a dose of 50 mg/kg once daily for seven days. Following the final dose, ethanol was administered to induce acute gastric mucosal injury. Quantitative image analysis using ImageJ software revealed that SH1 significantly reduced the gastric lesion area to 2.50 ± 0.50 mm², compared to 12.20 ± 0.50 mm² in the ulcer control group. Compound SH2 also showed substantial protection, with a lesion area of 3.40 ± 0.50 mm², while the remaining derivatives exhibited progressively weaker protective effects.

Histopathological examination of the gastric tissues provided further validation of the macroscopic findings. The normal control group displayed intact epithelial lining and well-organized gastric glands. In contrast, the ethanol-treated group exhibited severe disruption, hemorrhage, edema, and inflammatory cell infiltration. Pretreatment with SH1 and SH2 resulted in the preservation of gastric mucosal architecture, with minimal edema and inflammatory changes. The histological integrity observed in these groups correlated strongly with the quantitative reduction in lesion area, suggesting that the most active compounds effectively prevented the structural damage associated with ethanol-induced injury.

Assessment of oxidative stress biomarkers in serum revealed that ethanol administration significantly decreased superoxide dismutase and catalase activities while increasing malondialdehyde levels, a marker of lipid peroxidation. SH1 demonstrated the most significant antioxidant activity, restoring superoxide dismutase activity to 420.33 ± 0.58 U/mL and catalase activity to 95.00 ± 2.00 U/mL, values closely approximating those of the omeprazole-treated group. Additionally, SH1 significantly reduced malondialdehyde levels to 122.33 ± 2.52 nmol/mL, indicating a potent inhibition of lipid peroxidation. These biochemical findings suggest that the gastroprotective effect of SH1 is associated with the restoration of systemic antioxidant status and the mitigation of oxidative stress.

Structure-activity relationship analysis indicated that the nature of the terminal aromatic substituent plays a critical role in determining biological efficacy. SH1, which contains a para-bromobenzylidene substituent, exhibited the highest activity, likely due to increased lipophilicity and favorable hydrophobic interactions. SH2, featuring a para-hydroxyl group, showed strong antioxidant properties but slightly lower gastroprotective efficacy. In contrast, heteroaromatic derivatives such as those containing thiophene, thiazole, or indole rings displayed weak to moderate activity. Molecular docking studies provided complementary insights, revealing that SH2 had a more favorable predicted docking score than SH1, suggesting that binding affinity alone does not fully account for the observed in vivo efficacy.

The study acknowledges several limitations, including the small sample size of three animals per group, which was designed as an initial screening study rather than a definitive efficacy trial. The biological assessment was confined to an acute ethanol-induced model, and the oxidative stress biomarkers were measured in serum rather than gastric tissue. Furthermore, the precise molecular mechanisms, including specific inflammatory pathways and target interactions, require further investigation. Despite these constraints, the integrated approach of this study provides a robust foundation for the rational design of novel benzimidazole-based gastroprotective agents.

In conclusion, the synthesis and evaluation of benzimidazole-based hydrazone derivatives have identified SH1 as a promising lead compound with gastroprotective activity comparable to omeprazole. The combination of chemical synthesis, histopathological analysis, and biochemical profiling demonstrates that structural modifications to the hydrazone moiety can significantly influence biological efficacy. These findings underscore the importance of considering multiple molecular and biological determinants when optimizing this scaffold for the development of new anti-ulcer therapeutics.

Subject of Research: Synthesis and evaluation of benzimidazole-hydrazone derivatives as gastroprotective agents

Article Title: Design and synthesis of novel benzimidazole-based hydrazones as potential gastroprotective agents: Antioxidant, histopathological, and structure–activity relationship studies in an ethanol-induced gastric ulcer rat model

Article References: Ismael Shwayekh, S. A., Alinezhad, H., Tajbakhsh, M., Kadhum, A. A. H., & Awad, A. A.-H. (2026). Design and synthesis of novel benzimidazole-based hydrazones as potential gastroprotective agents: Antioxidant, histopathological, and structure–activity relationship studies in an ethanol-induced gastric ulcer rat model. Results in Chemistry, 31, Article 103997. https://doi.org/10.1016/j.rechem.2026.103997

Image Credits: AI Generated

DOI: 10.1016/j.rechem.2026.103997

Keywords: benzimidazole, hydrazone, gastroprotective, gastric ulcer, oxidative stress, structure-activity relationship, medicinal chemistry, rat model, omeprazole, antioxidant, Design, synthesis