Response surface-optimized Cycas revoluta leaf extract attenuates experimental ulcerative colitis through anti-inflammatory and oxidative stress-related mechanisms.

Cycas revoluta Thunb. has traditionally been used for the management of gastrointestinal and inflammatory disorders, but its bioactive constituents and anti-inflammatory potential remain insufficiently characterized. This study aimed to optimize the extraction of phenolic-rich compounds from C. revoluta leaves and evaluate the anti-inflammatory and coloprotective effects of the optimized extract against experimental ulcerative colitis (UC). Four extraction techniques, namely Soxhlet extraction, maceration, ultrasound-assisted extraction (UAE), and microwave-assisted extraction (MAE), were compared based on extraction yield, total phenolic content (TPC), total flavonoid content (TFC), antioxidant, and antibacterial activities. The most effective method was subsequently optimized using response surface methodology (RSM) using a Box-Behnken design (BBD), followed by phytochemical investigation and biological evaluation in rats with acetic acid-induced UC. Maceration showed the best performance, yielding the highest TPC (44.21 mg GAE g-1 DM), TFC (33.77 mg RE g-1 DM), DPPH inhibition (82.2%; IC50 = 37.61 μg mL-1), and antibacterial activity. RSM optimization further enhanced the recovery of bioactive constituents. Phytochemical investigation led to the isolation and structural identification of naringenin (1), 2,3-dihydrohinokiflavone (2), and amentoflavone (3). In the UC model, the optimized extract significantly improved colon length, disease activity index, and histopathological alterations. Moreover, it reduced TNF-α, nitric oxide, and VEGF levels while increasing HO-1 expression. Hence, the optimized C. revoluta extract exhibited promising coloprotective and anti-inflammatory effects, associated with modulation of inflammatory and oxidative stress-related responses, providing experimental support for its traditional gastrointestinal applications and its potential as a source of bioactive compounds for further development against inflammatory bowel diseases.