Polygonum capitatum (Buch.-Ham. ex D. Don) H. Gross is a perennial herb belonging to the Polygonaceae family, mainly distributed in Southwestern China. P. capitata is edible and boasts a high nutritional profile, and the entire plant serves medicinal purposes. According to the Guangxi Materia Medica, it has the functions of “relieving wind-dampness, enhancing blood circulation, and easing pain”. P. capitata is a major component of the traditional Chinese medicine formula, Re-Lin-Qing, which is widely used for treating urinary calculi (urolithiasis). However, its specific mechanisms of action remain unclear. In this study, we employed molecular biology, molecular dynamics, and cellular biology strategies to develop a rat experimental model of oxalate-induced urolithiasis and a cell model of oxalate-induced injury to study the active constituents and molecular mechanisms of P. capitata in inhibiting oxalate stone formation both in vivo and in vitro. The results show that in vivo, P. capitata significantly reduced the formation rate of oxalate stones in rats, decreased the levels of urinary oxalate, sodium, potassium, calcium, and magnesium, while increasing urine pH, urinary citrate levels, and urine excretion. Moreover, P. capitata significantly lowered serum creatinine levels in oxalate stone model rats and mitigated kidney damage. In vitro, treatment with P. capitata extract effectively alleviated oxalate-induced oxidative stress in HK-2 cells, reducing the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), while increasing ATP levels and inhibiting oxalate-induced apoptosis. LC-MS analysis of P. capitata components, in combination with transcriptomics, network pharmacology, and metabolomics sequencing, indicated that myricetin might be one of its potential bioactive compounds. Both P. capitata extract and its active compound, myricetin, significantly reversed the oxalate-induced decrease in phosphatidyqinositol-3 kinase (PI3K) and extracellular regulated protein kinases (ERK) levels and inhibited the overexpression of oxidative stress-related proteins. Further analysis using cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) experiments revealed that myricetin exhibits strong binding affinity to phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PI3KCA). Moreover, PI3K inhibitors reversed the protective effects of P. capitata and myricetin on oxalate-induced cell injury models. P. capitata exerts its anti-urolithiasis effects by alleviating oxidative stress through a multi-component, multi-target synergistic mechanism. Additionally, myricetin, one of the bioactive components of P. capitata, directly binds to PIK3CA, promoting ERK expression, upregulating nuclear factor E2-related factor-2 (NRF2) levels, and subsequently reducing oxidative stress, thereby inhibiting oxalate stone formation and alleviating kidney injury.

Osteoarthritis (OA) is a commonly occurring regressive articulation disease. Bioactive peptides derived from food have been reported to have excellent inhibitory effects on inflammatory responses. In this study, we evaluated the effects of Chinese giant salamander bone collagen peptides (CBCPs) on macrophage inflammation stimulated by lipopolysaccharide (LPS), and explored its protective effect against OA by an animal model of rat osteoarthritis. CBCPs were prepared from Chinese giant salamander bone by enzymatic hydrolysis. Under the optimal digestion conditions of neutral protease 7000 U/g, temperature 47 ℃, pH 7.0, material-liquid ratio 1:10, and digestion 6 h, CBCPs showed the strongest anti-inflammatory activity. After ultrafiltration, the 300-1000 Da peptide (named Ad-CP) showed the strongest anti-inflammatory effect, significantly reducing the release of NO, and the serection of IL-6, and TNF-α in inflammatory macrophages and inhibiting the chemotactic effect of macrophages. RNA FISH experiments revealed that lincRNA-Cox2 expression induced by LPS was inhibited by Ad-CP. Mechanistic analysis showed that Ad-CP suppressed NF-κB signaling via lincRNA-Cox2 by small interfering RNA, thereby reducing LPS-induced macrophage inflammation. Analysis of a rat osteoarthritis model showed that treatment with Ad-CP inhibited joint damage, macrophage infiltration and cartilage damage, and down-regulated the levels of pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α) in the joint fluid of OA rats. And treatment of Ad-CP suppressed lincRNA-Cox2 expression and inhibited the phosphorylation of NF-κB p65 and IκBα in knee joint tissue. In conclusion, Ad-CP alleviated the symptoms of osteoarthritis in OA rats through targeting the lincRNA-Cox2/NF-κB axis.

The skin of the Chinese giant salamander (Andrias davidianus) is a rich source of collagen. However, current research indicates limited efficiency and activity in collagen protease hydrolysis from this source. Further enzymatic hydrolysis to produce small molecular weight active peptides and their antitumor potential remain underexplored. This study employed a two-step enzymatic hydrolysis method to prepare small molecular weight collagen peptides (SMWCPs), followed by ultrafiltration separation. The extraction process was optimized using single-factor and response surface methodology. The amino acid composition of SMWCPs was analyzed, and their antitumor activity was assessed in vitro through cell migration, cell cycle, and apoptosis assays. Results revealed a negative correlation between collagen peptide molecular weight and antitumor activity, with optimal antitumor activity observed for peptides with a molecular weight of 300–1 000 Da (neutral protease hydrolyzed Chinese giant salamander skin collagen peptides (NP-GSKCP)). Optimal extraction conditions were: enzyme dosage 8 000 U/g, enzymatic hydrolysis temperature 52.6 °C, enzymatic hydrolysis pH 7.1, and enzymatic hydrolysis time 4.3 h, yielding 87.82% NP-GSKCP-IV. Notably, NP-GSKCP-IV contained 55.31% hydrophobic amino acids. Treatment of A549 cells with 5 mg/mL NP-GSKCP-IV significantly altered cell morphology, inhibited migration, arrested the cell cycle at G0/G1 phase, and induced early apoptosis. This study contributes to the development of efficient extraction techniques for antitumor active ingredients from Chinese giant salamander skin and informs the potential development of medicinal functional foods.