Kuwanon G

Int J Mol Sci. 2018 May 22;19(5). pii: E1542.

Protein Tyrosine Phosphatase 1B Inhibition and Glucose Uptake Potentials of Mulberrofuran G, Albanol B, and Kuwanon G from Root Bark of Morus alba L. in Insulin-Resistant HepG2 Cells: An In Vitro and In Silico Study.[Pubmed: 29786669]

Type II diabetes mellitus (T2DM) is the most common form of diabetes and has become a major health problem across the world. The root bark of Morus alba L. is widely used in Traditional Chinese Medicine for treatment and management of diabetes.
METHODS AND RESULTS:
The aim of the present study was to evaluate the enzyme inhibitory potentials of three principle components, mulberrofuran G (1), albanol B (2), and Kuwanon G (3) in M. alba root bark against diabetes, establish their enzyme kinetics, carry out a molecular docking simulation, and demonstrate the glucose uptake activity in insulin-resistant HepG2 cells. Compounds 1⁻3 showed potent mixed-type enzyme inhibition against protein tyrosine phosphatase 1B (PTP1B) and α-glucosidase. In particular, molecular docking simulations of 1⁻3 demonstrated negative binding energies in both enzymes. Moreover, 1⁻3 were non-toxic up to 5 μM concentration in HepG2 cells and enhanced glucose uptake significantly and decreased PTP1B expression in a dose-dependent manner in insulin-resistant HepG2 cells.
CONCLUSIONS:
Our overall results depict 1⁻3 from M. alba root bark as dual inhibitors of PTP1B and α-glucosidase enzymes, as well as insulin sensitizers. These active constituents in M. alba may potentially be utilized as an effective treatment for T2DM.

Eur J Med Chem. 2018 Jan 20;144:277-288.

Naturally occurring Diels-Alder-type adducts from Morus nigra as potent inhibitors of Mycobacterium tuberculosis protein tyrosine phosphatase B.[Pubmed: 29275228 ]

Mycobacterium tuberculosis (Mtb) protein tyrosine phosphatases A and B (PtpA and PtpB) have been recognized as potential molecular targets for the development of new therapeutic strategies against tuberculosis (TB). In this context, we have recently reported that the naturally occurring Diels-Alder-type adduct Kuwanol E is an inhibitor of PtpB (Ki = 1.6 ± 0.1 μM).
METHODS AND RESULTS:
Here, we describe additional Diels-Alder-type adducts isolated from Morus nigra roots bark that inhibit PtpB at sub-micromolar concentrations. The two most potent compounds, namely Kuwanon G and Kuwanon H, showed Ki values of 0.39 ± 0.27 and 0.20 ± 0.01 μM, respectively, and interacted with the active site of the enzyme as suggested by kinetics and mass spectrometry studies. Molecular docking coupled with intrinsic fluorescence analysis and isothermal titration calorimetry (ITC) further characterized the interaction of these promising PtpB inhibitors. Notably, in an Mtb survival assay inside macrophages, Kuwanon G showed inhibition of Mtb growth by 61.3%.
CONCLUSIONS:
All these results point to the common Diels-Alder-type adduct scaffold, and highlight its relevance for the development of PtpB inhibitors as candidate therapeutics for TB.

J Ethnopharmacol. 2003 Feb;84(2-3):181-5.

Kuwanon G: an antibacterial agent from the root bark of Morus alba against oral pathogens.[Pubmed: 12648813]

Kuwanon G was isolated from the ethyl acetate fraction of methanol extract of Morus alba and its structure was elucidated by 13C-NMR, 1H-NMR and FAB-MS.
METHODS AND RESULTS:
Antibacterial activity of Kuwanon G was investigated by the minimum inhibitory concentration (MIC) test and the viable cell count method. MIC of Kuwanon G against Streptococcus mutans causing dental caries was determined to be 8.0 microg/ml.
CONCLUSIONS:
The bactericidal test showed that Kuwanon G completely inactivated S. mutans at the concentration 20 microg/ml in 1 min. Kuwanon G also significantly inhibited the growth of other cariogenic bacteria such as Streptococcus sobrinus and Streptococcus sanguis, and Porpyromonas gingivalis causing periodontitis. Transmission electron microscopy (TEM) of Kuwanon G treated cells demonstrated remarkable morphological damage of the cell wall and condensation of the cytoplasm.

Toxicol Appl Pharmacol. 2018 Feb 15;341:56-63.

Kuwanon G attenuates atherosclerosis by upregulation of LXRα-ABCA1/ABCG1 and inhibition of NFκB activity in macrophages.[Pubmed: 29355567 ]

Atherosclerosis is characterized by chronic inflammation in vascular wall. Previous studies suggest that Kuwanon G (KWG) exerts anti-inflammatory activities. However, the effect of KWG on atherosclerosis remains unexplored. AIMS: To explore whether KWG affects macrophage foam cell formation in vitro and atherogenesis in vivo.
METHODS AND RESULTS:
RAW 264.7 macrophages were stimulated with ox-LDL for 24h to induce foam cell formation and treated with KWG. Foam cell formation was determined by ORO staining and enzymatic analysis. Pro-inflammatory cytokines mRNA levels were tested by Real-time PCR method. Further molecular mechanism was investigated using Western blot. In vivo, ApoE-/- mice were fed with high-fat diet and intraperitoneally injected with KWG. Atherosclerotic lesion was accessed by H&E and ORO staining. Plaque composition was evaluated by immunohistochemistry and Sirius Red staining. Serum lipid profile and inflammatory cytokines were evaluated by enzymatic method and ELISA. KWG significantly decreased intracellular lipid accumulation and inflammatory cytokines mRNA levels in macrophages through enhancing LXRα-ABCA1/ABCG1 pathway and inhibiting NFκB activation. Administrated with KWG remarkably reduced the atherosclerotic lesion areas and macrophage content in the plaque of high-fat diet fed ApoE-/- mice. KWG also reduced hyperlipidemia and serum inflammatory cytokines in vivo.
CONCLUSIONS:
Taken together, these data highlight that KWG can attenuate atherosclerosis through inhibiting foam cell formation and inflammatory response.

Biochem Biophys Res Commun. 1995 Aug 15;213(2):594-9.

Non-peptide bombesin receptor antagonists, kuwanon G and H, isolated from mulberry.[Pubmed: 7646517]

METHODS AND RESULTS:
Kuwanon G and H, isolated from the methanol extract of Morus bombycis, inhibited specific binding of [125I]gastrin-releasing peptide (GRP) to GRP-preferring receptors in murine Swiss 3T3 fibroblasts with Ki values of 470 and 290 nM, respectively. Kuwanon H was one order of magnitude less potent for inhibiting [125I]bombesin binding to neuromedin B (NMB)-preferring receptors in rat esophagus membranes. This compound antagonized bombesin-induced increases in the cytosolic free calcium concentration and GRP-induced DNA synthesis in Swiss 3T3 cells.
CONCLUSIONS:
Thus, kuwanon H, and possibly Kuwanon G also, are specific antagonists for the GRP-preferring receptor and can be useful for studying the physiological and pathological role of GRP.

Phytother Res. 2014 Nov;28(11):1713-9.

Effect of Kuwanon G isolated from the root bark of Morus alba on ovalbumin-induced allergic response in a mouse model of asthma.[Pubmed: 25116225 ]

The root bark of Morus alba L. (Mori Cortex Radicis; MCR) is traditionally used in Korean medicine for upper respiratory diseases.
METHODS AND RESULTS:
In this study, we investigated the antiasthmatic effect of Kuwanon G isolated from MCR on ovalbumin (OVA)-induced allergic asthma in mice. Kuwanon G (1 and 10 mg/kg) was administered orally in mice once a day for 7 days during OVA airway challenge. We measured the levels of OVA-specific IgE and Th2 cytokines (IL-4, IL-5, and IL-13) in the sera or bronchoalveolar lavage (BAL) fluids and also counted the immune cells in BAL fluids. Histopathological changes in the lung tissues were analyzed. Kuwanon G significantly decreased the levels of OVA-specific IgE and IL-4, IL-5, and IL-13 in the sera and BAL fluids of asthma mice. Kuwanon G reduced the numbers of inflammatory cells in the BAL fluids of asthma mice. Furthermore, the pathological feature of lungs including infiltration of inflammatory cells, thickened epithelium of bronchioles, mucus, and collagen accumulation was inhibited by Kuwanon G.
CONCLUSIONS:
These results indicate that Kuwanon G prevents the pathological progression of allergic asthma through the inhibition of lung destruction by inflammation and immune stimulation.

Biomed Chromatogr. 2018 Jul 5:e4328.

Comparative study of chemical composition and active components against α-glucosidase of various medicinal parts of Morus alba L.[Pubmed: 29975423]

Morus alba L has long been used as fodder and as a traditional medicine. Various parts of M. alba (Cortex mori, Ramulus mori, Folium mori and Fructus mori) have various bioactivities, however, most current evidence focused on anti-diabetic properties. In spite of their wide use, few studies compared the chemical composition and active components against α-glucosidase of the various medicinal parts of M. alba.
METHODS AND RESULTS:
In this study, we developed an HPLC method for simultaneous quality control and discrimination of Cortex mori, Ramulus mori, Folium mori and Fructus mori using thirteen marker compounds. We found that quercetin, morin, Kuwanon G, sanggenon C, morusin, mulberroside A and rutin were chemically distinct among the various medicinal parts of M. alba. A spectrum-effect relationship method was established to compare α-glucosidase inhibitory activity of various batches of samples to determine the activity of the primary active components against α-glucosidase. Taken together with molecular docking data, we found that prenylated flavonoids (morin, sanggenon C, Kuwanon G and morusin), flavonols (kaempferol, quercetin, rutin and isoquercitrin) and alkaloids (1-deoxynojirimycin) were small molecule α-glucosidase inhibitory ingredients.
CONCLUSIONS:
In conclusion, we laid a solid foundation for effective substance identification in various parts of M. alba, and simultaneously provided a basis for their quality control.