Tetragonia tetragonoides (Pall.) Kuntze, called New Zealand spinach (NZS), is an edible plant used in salad in Western countries and has been used to treat gastrointestinal diseases in traditional medicine. We examined the anti-obesity and anti-hyperuricemic effects of NZS and the underlying mechanisms in high-fat diet (HFD)-induced obese mice. Mice were fed a normal-fat diet (NFD); high-fat diet (HFD); HFD with 75, 150, or 300 mg/kg NZS extract; or 245 mg/kg Garcinia cambogia (GC) extract. NZS decreased body weight gain, total white adipose tissue (WAT), liver weight, and size of adipocytes and improved hepatic and plasma lipid profiles. With NZS, the plasma levels of the leptin and uric acid were significantly decreased while the levels of the adiponectin were increased. Furthermore, NZS decreased the expression levels of adipogenesis-related genes and xanthine oxidoreductase (XOR), which is involved in uric acid production, while increasing that of proteins associated with fatty acid oxidation. UPLC analysis revealed that NZS contained 6-methoxykaempferol-3-O-β-d-glucosyl(1′′′→2′′)-β-d-glucopyranoside, 6-methoxykaempferol-3-O-β-d-glucosyl(1′′′→2′′)-β-d-glucopyranosyl-(6′′′′-caffeoyl)-7-O-β-d-glucopyranoside, and 6,4′-dimethoxykaempferol-3-O-β-d-glucosyl(1′′′→2′′)-β-d-glucopyranosyl-(6′′′′-caffeoyl)-7-O-β-d-glucopyranoside. These results suggest that NZS exerts anti-obesity, anti-hyperlipidemia, and anti-hyperuricemic effects in HFD-induced obese mice, which are partly explained by regulation of lipid-metabolism-related genes and proteins and decreased expression of XOR.

Chrysanthemum indicum Linne flower (CF) and Cinnamomum cassia (L.) J. Presl bark (CB) extracts have been used as the main ingredients in several prescriptions to treat the hyperuricemia and gout in traditional medicine. In the present study, we investigated the antihyperuricemic effects of DKB114, a CF, and CB mixture, and the underlying mechanisms in vitro and in vivo. DKB114 markedly reduced serum uric acid levels in normal rats and rats with PO-induced hyperuricemia, while increasing renal uric acid excretion. Furthermore, it inhibited the activity of xanthine oxidase (XOD) in vitro and in the liver in addition to reducing hepatic uric acid production. DKB114 decreased cellular uric acid uptake in oocytes and HEK293 cells expressing human urate transporter (hURAT)1 and decreased the protein expression levels of urate transporters, URAT1, and glucose transporter, GLUT9, associated with the reabsorption of uric acid in the kidney. DKB114 exerts antihyperuricemic effects and uricosuric effects, which are accompanied, partially, by a reduction in the production of uric acid and promotion of uric acid excretion via the inhibition of XOD activity and reabsorption of uric acid. Therefore, it may have potential as a treatment for hyperuricemia and gout.

Toona sinensis leaf is used as a seasonal vegetable in Korea. A 70% ethanol extract of these leaves exhibited potent xanthine oxidase (XO) inhibition, with a 50% inhibitory concentration (IC₅₀) of 78.4 µM. To investigate the compounds responsible for this effect, bioassay-guided purification led to the isolation of five constituents, identified as quercetin-3-O-rutinoside, quercetin-3-O-β-d-glucopyranoside, 1,2,3,4,6-penta-O-galloyl-β-d-glucopyranose (compound 3), quercetin-3-O-α-l-rhamnopyranoside, and kaempferol-3-O-α-l-rhamnopyranoside. Compound 3 showed the most potent inhibition of XO, with an IC₅₀ of 2.8 µM. This was similar to that of allopurinol (IC₅₀ = 2.3 µM), which is used clinically to treat hyperuricemia. Kinetic analyses found that compound 3 was a reversible noncompetitive XO inhibitor. In vivo, the T. sinensis leaf extract (300 mg/kg), or compound 3 (40 mg/kg), significantly decreased serum uric acid levels in rats with potassium oxonate-induced hyperuricemia. Furthermore, ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis identified a high level of compound 3 in the leaf extract. These findings suggest that T. sinensis leaves could be developed to produce nutraceutical preparations.

Atopic dermatitis is a persistent inflammatory skin disorder. Siraitia grosvenorii fruits (monk fruit or nahangwa in Korean, NHG) are used as a natural sweetener and as a traditional medicine for the treatment of asthma and bronchitis. We evaluated the activity of S. grosvenorii residual extract (NHGR) on allergic inflammation of atopic dermatitis in a Dermatophagoides farinae mite antigen extract (DfE)-treated NC/Nga murine model and in vitro. Oral administration of NHGR significantly reduced epidermal hyperplasia and inflammatory cell infiltration in the skin lesions of DfE-induced atopic dermatitis, as well as the dermatitis severity score. NHGR reduced serum immunoglobulin E levels. Splenic concentrations of IFN-γ, interleukin (IL)-4, IL-5, and IL-13 were reduced by NHGR administration. Immunohistofluorescence staining showed that NHGR administration increased the protein levels of claudin-1, SIRT1, and filaggrin in atopic dermatitis skin lesions. In addition, NHGR inhibited the phosphorylation of mitogen-activated protein kinases and decreased filaggrin and chemokine protein expression in TNF-α/IFN-γ-induced human keratinocytes. Moreover, NHGR also inhibited histamine in mast cells. The quantitative analysis of NHGR revealed the presence of grosvenorine, kaempferitrin, and mogrosides. These results demonstrate that NHGR may be an efficient therapeutic agent for the treatment of atopic dermatitis.

Osteoarthritis (OA) is a degenerative joint disease characterised by cartilage degeneration and chondrocyte inflammation. We investigated the anti-inflammatory effects of the Siraitia grosvenorii residual extract (SGRE) in lipopolysaccharide (LPS)-induced RAW264.7 macrophages in vitro and its anti-osteoarthritic effects in a monosodium iodoacetate (MIA)-induced OA rat model. SGRE dose-dependently decreased nitric oxide (NO) production in LPS-induced RAW264.7 cells. Moreover, SGRE reduced the pro-inflammatory mediator (cyclooxygenase-2 (COX2), inducible NO synthase (iNOS), and prostaglandin E2 (PGE2)) and pro-inflammatory cytokine (interleukin-(IL)-1β, IL-6, and tumour necrosis factor (TNF-α)) levels. SGRE suppressed nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathway activation in RAW264.7 macrophages, thus reducing inflammation. Rats were orally administered SGRE (150 or 200 mg/kg) or the positive control drug JOINS (20 mg/kg) 3 days before MIA injection, and once daily for 21 days thereafter. SGRE elevated the hind paw weight-bearing distribution, thus relieving pain. It also reduced inflammation by inhibiting inflammatory mediator (iNOS, COX-2, 5-LOX, PGE2, and LTB4) and cytokine (IL-1β, IL-6, and TNF-α) expression, downregulating cartilage-degrading enzymes, such as MMP-1, -2, -9, and -13. SGRE significantly reduced the SOX9 and extracellular matrix component (ACAN and COL2A1) levels. Therefore, SGRE is a potential therapeutic active agent against inflammation and OA.

Dryopteris crassirhizoma rhizomes are used as a traditional medicine in Asia. The EtOAc extract of these roots has shown potent xanthine oxidase (XO) inhibitory activity. However, the main phloroglucinols in D. crassirhizoma rhizomes have not been analyzed. Thus, we investigated the major constituents responsible for this effect. Bioassay-guided purification isolated four compounds: flavaspidic acid AP (1), flavaspidic acid AB (2), flavaspidic acid PB (3), and flavaspidic acid BB (4). Among these, 1 showed the most potent inhibitory activity with a half-maximal inhibitory concentration (IC₅₀) value of 6.3 µM, similar to that of allopurinol (IC₅₀ = 5.7 µM) and better than that of oxypurinol (IC₅₀ = 43.1 µM), which are XO inhibitors. A comparative activity screen indicated that the acetyl group at C3 and C3′ is crucial for XO inhibition. For example, 1 showed nearly 4-fold higher efficacy than 4 (IC₅₀ = 20.9 µM). Representative inhibitors (1–4) in the rhizomes of D. crassirhizoma showed reversible and noncompetitive inhibition toward XO. Furthermore, the potent inhibitors were shown to be present in high quantities in the rhizomes by a UPLC-QTOF-MS analysis. Therefore, the rhizomes of D. crassirhizoma could be used to develop nutraceuticals and medicines for the treatment of gout.