This study explored the protective and therapeutic effects of Heracleum lasiopetalum extract in female rats with acetic acid-induced UC. Oral administration of the extract resulted in dose-dependent improvements in both macroscopic and microscopic colonic inflammation and injury markers in the animal model. Utilizing female rats allowed the investigation of gender-specific differences in UC, relevant to humans, while also establishing a foundational understanding of the herb's effects in one gender, laying the groundwork for future research. This approach helped minimize variability introduced by gender-related factors. Utilizing animal models is crucial for understanding the mechanisms involved in UC and discovering potential drugs (
41).
In different studies, acetic acid concentrations of 3 - 10% have been used to induce UC by applying 1 - 2 milliliters of acetic acid to the colon for a contact time of 15 to 30 seconds. Currently, a common animal model used for inducing UC involves the intrarectal injection of 4% acetic acid with a contact time ranging from 15 to 30 seconds with the colon. The examination of the pharmacological effects of chemical substances occurs within 24 hours after induction, with various treatment periods (
42-
46). Our previous study identified an optimal model, involving 10 minutes of 4% acetic acid contact, UC confirmation, initiation of treatment 72 hours post-acid administration, and monitoring up to six days post-UC confirmation. This model considers key factors, including acetic acid contact duration, precise UC confirmation timing, treatment period, and non-spontaneous recovery. For protective assessment, administering the extract seven days before UC induction until three days post-acid administration, with UC confirmation on the third day, proved effective. Our rat model, induced with acetic acid, mimics key features of acute inflammation flare-ups seen in human UC, including symptoms like diarrhea, rectal bleeding, and colonic mucosa inflammation/ulceration.
This model provides a platform to study potential therapeutic interventions during this critical phase of the disease (
37), laying the groundwork for further exploration of Heracleum lasiopetalum extract as a potential supplement treatment option, which could complement existing therapies for UC.
On the final day of assessing food consumption in treatment groups with plant extract, a notable increase was observed. The rats' weights at the study's end did not significantly differ from the normal and positive control groups, suggesting improved digestive system function and enhanced absorption efficiency. However, no significant improvements in weight or food consumption were noted in the protective extract groups compared to the normal and positive control groups. Examining colon weight in different treatment groups revealed the most significant reduction in the positive control group, followed by the 40% extract treatment group (
Figure 2B). In the protective groups, the normal group showed a significant difference from all others, while the remaining protective groups did not differ significantly from each other (
Figure 2A). These findings indicate potential benefits of plant extract treatments on food consumption, weight maintenance, and colon weight reduction, suggesting positive effects on digestive system function.
Overall, the diagnosis of UC in patients involves considering several factors. In microscopic examination, the severity of inflammation indicates inflammatory cell infiltration, including neutrophils. Additionally, the degree of inflammation suggests involvement of different parts of the colon wall, such as the mucosa, submucosa, and across the wall (
47). In our study, inflammation was examined both macroscopically and microscopically. In protective groups, pretreatment with 5%, 10%, and 40% plant extract for 7 days before UC induction did not significantly reduce inflammation scores compared to the negative control, indicating limited preventive effects. In treatment groups, the plant extract consistently reduced inflammation scores, indicating its suppressive effect on acetic acid-induced inflammation. Photomicrographs H, I, and G in
Figure 4B confirmed decreased inflammatory cell infiltration, particularly neutrophils, reinforcing the extract's potential suppressive effect on inflammation. This suggests a possible mechanism involving the inhibition of neutrophil migration and activity. Post-treatment with the plant extract for 6 days after UC induction revealed dose-dependent improvements. The 40% and 10% concentrations demonstrated superior therapeutic efficacy, significantly reducing ulceration, hyperemia, inflammation, and lesion depth compared to untreated controls. In contrast, the 5% dose exhibited lesser effectiveness, underscoring the importance of dose in eliciting pharmacological responses.
To date, understanding the physiological pathways involved in intestinal wound healing remains incomplete. Both acute and chronic intestinal inflammation involve macrophages and neutrophils, which contribute to localized tissue damage through the release of reactive oxygen radicals and tissue-degrading enzymes, triggered by pro-inflammatory cytokines and cell-bound proinflammatory peptides (
48). Severe tissue damage prompts the migration of myofibroblasts to the injury site, a critical process involving wound contraction and extracellular matrix (ECM) generation linked to physiological changes in chronic inflammation (
49,
50). Importantly, chronic or recurrent inflammation is a prerequisite for the initiation of intestinal fibrosis, a significant complication in patients with IBD (
48,
51). In our study, the 40% and 10% treatment extract groups effectively reduced fibrosis (
Figure 4D and
Table 5), potentially attributed to the plant's impact on reducing inflammation, thus preventing its exacerbation and the occurrence of fibrosis. In the protective groups, fibrosis was not observed in the normal and positive control groups on the third day, while it persisted in the other groups (
Figure 4C and
Table 5).
The anti-inflammatory effects observed in this study can be attributed to bioactive components in Heracleum lasiopetalum, notably flavonoids and phenolic compounds. Previous research has highlighted their abundant presence in Heracleum lasiopetalum extracts (
17,
25). Flavonoids may modulate NF-κB signaling, inhibiting the activation and reducing the expression of downstream pro-inflammatory cytokines like TNF-α and IL-1β (
27). Similarly, phenolic compounds in experimental UC models suppress NF-κB signaling, decreasing the production of cytokines such as TNF-α, IL-1β, and IL-6, thereby offering potential as anti-inflammatory agents (
28). Additionally, studies indicate alterations in total antioxidant capacity and increased reactive oxygen species levels in patients with IBD (
52). Flavonoids (
27) and phenolic acids (
28) possess antioxidant properties, countering oxidative stress in UC pathogenesis. These compounds may mitigate mucosal damage by inhibiting reactive oxygen species production and enhancing endogenous antioxidants (
29). Heracleum lasiopetalum extracts also exhibit broad-spectrum antimicrobial effects against both Gram-positive and Gram-negative bacteria (
19-
23). This antimicrobial activity could impact the intestinal microenvironment, holding potential significance in the context of UC. Our study has identified several biological effects of Heracleum lasiopetalum Boiss concerning UC. These effects include anti-inflammatory, wound healing, and anti-fibrotic actions, highlighting the plant's potential relevance as a supplementary therapy alongside standard drugs for UC.
5.1. Conclusions
This study provides novel evidence that Heracleum lasiopetalum extract effectively repairs acetic acid-induced colonic injury in female rats. The observed dose-dependent therapeutic potential in experimental UC suggests that Heracleum lasiopetalum may offer complementary support to conventional drugs, enhancing treatment outcomes by ameliorating both macroscopic and microscopic markers of inflammation and injury. While Heracleum lasiopetalum emerges as a promising supplementary phytotherapeutic agent, future research should focus on identifying its active phytochemicals, elucidating underlying mechanisms, and assessing its translational potential for clinical applications.