Daphnodorin C isolated from the stems of Daphne kiusiana Miquel attenuates airway inflammation in a mouse model of chronic obstructive pulmonary disease.

BACKGROUND: Since long-term or high-dose use of COPD medication causes adverse effects in patients with COPD, more effective and safer ways to manage COPD symptoms are required. Daphne kiusiana Miquel is a medicinal plant, but its anti-COPD efficacy was little studied. PURPOSE: We investigated the anti-COPD activity and molecular mechanism of action of active compounds isolated from D. kiusiana to find drug candidates for COPD. METHODS: We isolated seven compounds (1-7) in an ethyl acetate (EtOAc) fraction from D. kiusiana, and determined that seven compounds effectively control the inflammatory responsiveness in both PMA-stimulated lung epithelial cells (in vitro) and/or in COPD model mice using cigarette smoke- and lipopolysaccharides-exposed animals in vivo. RESULTS: We show that the ethyl acetate (EtOAc) fraction from D. kiusiana. suppresses inflammatory response in both PMA-stimulated human lung epithelial cells (in vitro) and COPD model mice (in vivo). The EtOAc fraction effectively suppresses various inflammatory responses, such as mucus secretion, ROS production, bronchial recruitment of inflammatory cells, and release of proinflammatory cytokines. Additionally, we isolated three compounds with anti-inflammatory efficacy from the EtOAc fraction, out of which daphnodorin C was the most effective. Finally, we demonstrated that daphnodorin C negatively regulates inflammatory gene expression by suppressing NF-κB and specific MAPK signaling pathways (JNK and p38) in vitro and in vivo. CONCLUSIONS: These results suggest that daphnodorin C could be a promising therapeutic alternative for managing COPD symptoms.

Rapid identification of isoprenylated flavonoids constituents with inhibitory activity on bacterial neuraminidase from root barks of paper mulberry (Broussonetia papyrifera).

This study was to assess the possibility of using competitive and slow binding experiments with affinity-based ultrafiltration UPLC-QTof-MS analysis to identify potent bacterial neuraminidase (bNA) inhibitors from the Broussonetia papyrifera roots extract. To isolate unbound compounds from the enzyme-binding complex, the root bark extracts were either incubated in the absence of bNA, in the presence of bNA, or with the time-dependent bNA before the ultrafiltration was performed. Thirteen flavonoids were separated from the target extract, and their inhibitory activities were tested against bNA. The isolated flavonoids exhibited potent inhibition against NA (IC50 = 0.7-54.0 µM). Our kinetic analysis of representative active flavonoids (1, 2, and 6) showed slow and time-dependent reversible inhibition. Additionally, chalcones exhibited noncompetitive inhibition characteristics, whereas flavonols and flavans showed mixed-type behavior. The computational results supported the experimental behaviors of flavonoids 2, 6, 10, and 12, indicating that bounded to the active site, but flavonoids 6 and 10 binds near but not accurately at the active site. Although this is mixed-type inhibition, their binding can be considered competitive.

Anticholinesterase potential of flavonols from paper mulberry (Broussonetia papyrifera) and their kinetic studies.

It is necessary to develop food additives to help treat chronic disorders like neurodegenerative diseases from medicinal plants. Ethanol extracts of paper mulberry were found to display significant inhibition against cholinesterases, enzymes that are strongly linked with Alzheimer's disease (AD). The active components were identified as prenylated flavonols (2-4) that inhibited two related human cholinesterases in a dose-dependent manner, with IC50's ranging between 0.8 and 3.1µM and between 0.5 and 24.7µM against human acetylcholinesterase (hAChE) and butylcholinesterase (BChE), respectively. Prenyl groups within these flavonols were found to play a critical role for inhibition because the parent compound 1, quercetin, was inactive (IC50>500µM) towards the target enzymes. Flavonols (2-4) showed mixed inhibition kinetics as well as slow and time-dependent reversible inhibition toward hAChE. The affinity between protein and inhibitors was investigated using fluorescence quenching. The affinity constants (KSA) of inhibitors increased in proportion to their inhibitory potencies.

α-Glucosidase inhibition and antihyperglycemic activity of prenylated xanthones from Garcinia mangostana.

An ethanol extract of the fruit case of Garcinia mangostan, whose most abundant chemical species are xanthones, showed potent α-glucosidase inhibitory activity (IC(50)=3.2 µg/ml). A series of isolated xanthones (1-16) demonstrated modest to high inhibition of α-glucosidase with IC(50) values of 1.5-63.5 µM. In particular, one hitherto unknown xanthone 16 has a very rare 2-oxoethyl group on C-8. Kinetic enzymatic assays with a p-nitrophenyl glucopyranoside indicated that one of them, compound (9) exhibited the highest activity (K(i)=1.4 µM) and mixed inhibition. Using, a physiologically relevant substrate, maltose, as substrate, many compounds (6, 9, 14, and 15) also showed potent inhibition which ranged between 17.5 and 53.5 µM and thus compared favorably with deoxynojirimycin (IC(50)=68.8 µM). Finally, the actual pharmacological potential of the ethanol extract was demonstrated by showing that it could elicit reduction of postprandial blood glucose levels. Furthermore, the most active α-glucosidase inhibitors (6, 9, and 14) were proven to be present in high quantities in the native seedcase by a HPLC chromatogram.

Xanthones with neuraminidase inhibitory activity from the seedcases of Garcinia mangostana.

This study was designed to gain deeper insights into the molecular properties of natural xanthones as neuraminidase inhibitors. A series of xanthones 1-12 was isolated from the seedcases of Garcinia mangostana and evaluated for bacteria neuraminidase inhibitory activity. Compounds 11 and 12 emerged to be new xanthones (mangostenone F, mangostenone G) which we fully spectroscopically characterized. The IC(50) values of compounds 1-12 were determined to range between 0.27-65.7 microM. The most potent neuraminidase inhibitor 10 which has an IC(50) of 270 nM features a 5,8-diol moiety on the B ring. Interestingly, structure-activity studies reveal that these xanthones show different kinetic inhibition mechanisms depending upon the arrangement of hydroxyl groups in the B ring. Compound 6 possessing a 6,7-diol motif on the B-ring operated under the enzyme isomerization model (k(5)=0.1144 microM(-1) s(-1), k(6)=0.001105 s(-1), and K(i)(app)=7.41 microM), whereas compound 10 possessing a 5,8-diol unit displayed simple reversible slow-binding inhibition (k(3)=0.02294 microM(-1) s(-1), k(4)=0.001025 s(-1), and K(i)(app)=0.04468 microM).

Polyphenols from Broussonetia papyrifera displaying potent alpha-glucosidase inhibition.

The organic extract of the roots of Broussonetia papyrifera showed extremely high alpha-glucosidase inhibitory activity with an IC50 of around 10 microg/mL. Due to its potency, subsequent bioactivity-guided fractionation of the chloroform extract led to 12 polyphenols, 1-12, 4 of which were identified as chalcones (1-4), another 4 as flavans (5-8), 2 as flavonols (9 and 10), and 2 others as the novel species benzofluorenones (11 and 12). Broussofluorenone A (11) and broussofluorenone B (12) emerged as new compounds possessing the very rare 5,11-dioxabenzo[b]fluoren-10-one skeleton. These compounds (1-12) were evaluated for alpha-glucosidase inhibitory activity to identify their inhibitory potencies and kinetic behavior. The most potent inhibitor, 10 (IC50=2.1 microM, Ki=2.3 microM), has an inhibitory activity slightly higher than that of the potent alpha-glucosidase inhibitor deoxynojirimycin (IC50=3.5 microM). The novel alpha-glucosidase inhibitors 11 (IC50=27.6 microM) and 12 (IC50=33.3 microM) are similar in activity to sugar-derived alpha-glucosidase inhibitors such as voglibose (IC50=23.4 microM). Interestingly, major constituents (1, 2, 6, 7, 9, and 10) of B. papyrifera displayed significant inhibitory activity with IC50 values of 5.3, 11.1, 12.0, 26.3, 3.6, and 2.1 microM, respectively. In kinetic studies, chalcones (1-4) exhibited noncompetitive inhibition characteristics, whereas the others (5-12) showed mixed behavior.