Silymarin, an antioxidant bioflavonoid, inhibits experimentally-induced peptic ulcers in rats by dual mechanisms

Natural products for gastric carcinoma prevention and treatment: Focus on their antioxidant stress actions in the Correa's cascade

BACKGROUND

Correa's cascade is a pathological process beginning from gastritis to gastric precancerous lesions, and finally to gastric carcinoma (GC). While the pathogenesis of GC remains unclear, oxidative stress plays a prominent role throughout the entire Correa's cascade process. Studies have shown that some natural products (NPs) could halt and even reverse the development of the Correa's cascade by targeting oxidative stress.

METHODS

To review the effects and mechanism by which NPs inhibit the Correa's cascade through targeting oxidative stress, data were collected from PubMed, Embase, Web of Science, ScienceDirect, and China National Knowledge Infrastructure databases from initial establishment to April 2023. NPs were classified and summarized by their mechanisms of action.

RESULTS

NPs, such as terpenoid, polyphenols and alkaloids, exert multistep antioxidant stress effects on the Correa's cascade. These effects include preventing gastric mucosal inflammation (stage 1), reversing gastric precancerous lesions (stage 2), and inhibiting gastric carcinoma (stage 3). NPs can directly impact the conversion of gastritis to GC by targeting oxidative stress and modulating signaling pathways involving IL-8, Nrf2, TNF-α, NF-κB, and ROS/MAPK. Among which polyphenols have been studied more and are of high research value.

CONCLUSIONS

NPs display a beneficial multi-step action on the Correa's cascade, and have potential value for clinical application in the prevention and treatment of gastric cancer by regulating the level of oxidative stress.

Ameliorative activity of aqueous leaf extract from Madhuca longifolia against diclofenac-administered toxicity on rat stomach and intestine

Madhuca longifolia, a tropical tree used as medicine and food, is known to have a beneficial effect against stomach gastric toxicity. Madhuca longifolia is used in treating cough, skin disease and nerve disorders. Diclofenac, a non-steroidal anti-inflammatory drug (NSAID), with overdosage and prolonged use, is known to cause gastric toxicity. Silymarin (SLY), a polyphenolic antioxidant flavonoid, is a derivative of Silybum marianum extracted from milk thistle seeds and fruits, has been widely used in the treatment of gastric ulcer. SLY was used as the standard drug to compare the effects with the Madhuca longifolia aqueous leaf extract treatment. The aim of the current study is to understand the effect of Madhuca longifolia aq. leaf extract on rat stomach and intestine against diclofenac-administered toxicity. Rats (n = 30) were divided into Group I normal control, Group II treated with diclofenac, Group III treated with diclofenac and Madhuca longifolia leaf extract, Group IV treated with diclofenac and silymarin, and Group V was treated with Madhuca longifolia leaf extract alone. After the study duration, rats were euthanized and tissue samples were analyzed for antioxidant, cytokine, protein expression levels and histopathological changes. Diclofenac treated rats had significant (p < 0.05) changes in levels of antioxidants, cytokines, protein expression and pathological changes as compared to rats treated with Madhuca longifolia. This study demonstrated that Madhuca longifolia leaf extract had gastroprotective activity in rats treated with diclofenac.

A Review of the Role of Flavonoids in Peptic Ulcer (2010-2020)

Peptic ulcers are characterized by erosions on the mucosa of the gastrointestinal tract that may reach the muscle layer. Their etiology is multifactorial and occurs when the balance between offensive and protective factors of the mucosa is disturbed. Peptic ulcers represent a global health problem, affecting millions of people worldwide and showing high rates of recurrence. Helicobacter pylori infection and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most important predisposing factors for the development of peptic ulcers. Therefore, new approaches to complementary treatments are needed to prevent the development of ulcers and their recurrence. Natural products such as medicinal plants and their isolated compounds have been widely used in experimental models of peptic ulcers. Flavonoids are among the molecules of greatest interest in biological assays due to their anti-inflammatory and antioxidant properties. The present study is a literature review of flavonoids that have been reported to show peptic ulcer activity in experimental models. Studies published from January 2010 to January 2020 were selected from reference databases. This review refers to a collection of flavonoids with antiulcer activity in vivo and in vitro models.

Modulatory effect of silymarin on nuclear factor-erythroid-2-related factor 2 regulated redox status, nuclear factor-κB mediated inflammation and apoptosis in experimental gastric ulcer

Non-steroidal anti-inflammatory drugs (NSAIDs) consumption has been commonly associated with gastric mucosal lesions including gastric ulcer. Silymarin (SM) is a flavonoid mixture with anti-oxidant and anti-inflammatory activities which explain its protective role against hepatic and renal injuries. However, its impact on gastric ulcer has not yet been elucidated. Thus we went further to investigate the potential protective effects of SM against indomethacin-induced gastric injury in rats. Pretreatment with SM (50 mg/kg orally) attenuated the severity of gastric mucosal damage as evidenced by decreasing ulcer index (UI) and ulcer score, improvement of disturbed histopathologicl features to be insignificant with those induced by the reference anti-ulcer drug. Pretreatment with SM also suppressed gastric inflammation by decreasing myeloperoxidase activity, tumer necrosis factor-α (TNF- α) and interleukin 6 (IL6) levels along with nuclear factor kappa B p65 (NF-κB) expression. Meanwhile, SM prevent gastric oxidative stress via inhibition of lipid peroxides formation, enhancement of glutathione peroxidase, superoxide dismutase activities and up-regulation of nuclear factor-erythroid-2-related factor 2 (Nrf2), the redox-sensitive master regulator of oxidative stress signaling. In conclusion, the results herein revealed that SM has a gastro-protective effect which is mediated via suppression of gastric inflammation, oxidative stress, increased the anti-oxidant and the cyto-protective defense mechanisms.

Effects of silymarin on methotrexate-induced nephrotoxicity in rats

Methotrexate (MTX) is widely used in the treatment of various malignancies and nononcological diseases but its use has been limited by its nephrotoxicity. Silymarin (SLY), a natural flavonoid, has been reported to have antioxidant, anti-inflammatory and anti-apoptotic effects. This study was carried out to determine whether SLY exerts a protective effect against MTX-induced nephrotoxicity. Rats were divided into six groups: Group 1 (saline, i.p., single injection), Group 2 (0.5% carboxymethyl cellulose (CMC), by gavage once daily for five consecutive days), Group 3 (SLY, 300 mg/kg per day, i.p. for five consecutive days), Group 4 (MTX, 20 mg/kg, i.p., single injection), Group 5 (MTX + CMC similarly as groups 2 and 4) and Group 6 (MTX + CMC + SLY similarly as groups 2, 3 and 4). Histopathologic alterations including apoptotic changes of the kidney were evaluated. MTX injection exhibited dilated Bowman's space, inflammatory cell infiltration, glomerular and peritubular vascular congestion and swelling of renal tubular epithelium cells. Apoptotic cell death was also markedly increased in renal tubules after MTX administration. SLY treatment resulted in statistically significant amelioration in the histological alterations and reduced the number of TUNEL-positive cells as compared with the MTX treated rats (p < 0.05). In conclusion, SLY treatment leads to a reduction on MTX-induced renal damage in rats. Since SLY is safe and acceptable for human consumption, further studies to define the exact mechanism of the protecting effect of SLY on MTX-induced nephrotoxicity and the optimum dosage of this compound would be useful.