**Background:** Stomach ulcers affect 5–10% of the global population and represent a serious public health burden. Current pharmacological treatments often cause adverse effects on gastrointestinal motor and digestive processes, prompting interest in safer herbal alternatives. Plants of the genus Rumex (Polygonaceae family) are rich in polyphenolic compounds including anthraquinones, flavonoids, and tannins, and have been used in traditional medicine for gastrointestinal disorders. However, the antiulcer activity of Rumex tianschanicus Losinsk, a perennial herb widely distributed in Central Asia, had not been previously evaluated.
**Methods:** The underground organs of R. tianschanicus were harvested in June 2021 in the Zailiyskiy Alatau region of Kazakhstan. Air-dried roots (1 kg) were extracted with 50% ethanol, and the anthraquinone–flavonoid complex (AFC) was obtained via precipitation with zirconium nitrate followed by removal of zirconium with sodium oxalate. The AFC contained anthraquinones (1.77%), flavonoids (6.95%), and tannins (13.39%). Six known compounds were isolated through sequential extraction with benzene and ethyl acetate, followed by column chromatography on silica gel, Sephadex LH-20, and polyamide. Compounds were identified as physcion (1), chrysophanol (2), emodin (3), isorhamnetin (4), quercetin (5), and myricetin (6) using UV, IR, NMR, and MS spectroscopic analyses.
For the in vivo study, 36 female Wistar rats (220–250 g) were divided into 5 groups: (1) Control – water-tween mixture intragastrically; (2) Stomach ulcer – indomethacin 25 mg/kg per os; (3) Prophylactic injection – AFC 100 mg/kg followed by indomethacin; (4) Single injection – AFC 100 mg/kg one hour before indomethacin; (5) Prolonged use – AFC 100 mg/kg for 10 days, with indomethacin given one hour after the last dose. Animals were euthanized with CO₂, stomachs were examined macroscopically, and histological sections were stained with hematoxylin and eosin. The Pauls' index (PI) was calculated as (average number of ulcerative defects per animal × percentage of animals with ulcers)/100, and the antiulcer activity index (AA) was calculated as PI_control/PI_experimental, with AA ≥ 2 considered positive.
**Key Results:** Body weight in the stomach ulcer group (210.2 ± 8.2 g) was significantly lower than control (225.5 ± 7.2 g, p < 0.05), while the prophylactic injection group (238.4 ± 6.7 g) and prolonged use group (255.5 ± 9.2 g) had significantly higher body weights than control (p < 0.05). Liver and stomach weights were significantly reduced in the ulcer group compared to control (p < 0.05) and significantly increased in the prophylactic group (p < 0.05).
Ulcer prevalence was 100% in controls, 92% in the untreated ulcer group, 60% with prophylactic AFC, 35% with single injection, and 30% with prolonged use. The number of punctate ulcers was significantly reduced in all treatment groups: prophylactic (2.1 ± 0.4), single injection (2.7 ± 0.6), and prolonged use (1.3 ± 0.5) compared to control (4.8 ± 0.9, p < 0.05). Large ulcers were also significantly reduced: prophylactic (1.2 ± 0.5), single injection (2.8 ± 0.8), and prolonged use (1.8 ± 0.3) versus control (4.6 ± 0.7, p < 0.05). The Pauls' index was 12.3 for control, 7.4 for ulcer group, 6.2 for prophylactic, 5.4 for single injection, and 6.1 for prolonged use. The antiulcer activity index was 2.3 for prophylactic use, 1.9 for single injection, and 2.1 for prolonged use, with values ≥ 2 indicating positive antiulcer activity.
Histological examination revealed that the control group (indomethacin only) showed pronounced infiltration of polymorphonuclear leukocytes, vascular plethora, diapedesis hemorrhages, and deep mucosal defects with focal desquamation reaching half to full thickness of the mucosa. The prophylactic group showed partial epithelialization of ulcerative defects with decreased inflammatory infiltration. The single injection group showed incomplete epithelialization with pyloric-type gland restructuring at the edges of deep defects. The prolonged use group demonstrated the most favorable outcomes with superficial mucosal defects, complete epithelialization, and no pyloric epithelial restructuring.
**Clinical Implications:** This study provides the first evidence that the anthraquinone–flavonoid complex from R. tianschanicus roots exhibits significant antiulcer activity in an indomethacin-induced gastric ulcer model. The complex's antiulcer activity index of 2.1 (prolonged use) and 2.3 (prophylactic use) meets the threshold for positive antiulcer activity. The proposed mechanism involves restoration of gastric mucosal protective ability, increased prostaglandin synthesis, and enhanced mucus production. The presence of known anti-inflammatory and antiulcer compounds (physcion, chrysophanol, emodin, isorhamnetin, quercetin, and myricetin) supports the therapeutic potential. These findings suggest that R. tianschanicus is a promising candidate for developing phytopreparations for treating gastric ulcers, though further research is needed to elucidate specific mechanisms and evaluate clinical safety and efficacy.