Search

Ethanol extract of soybean (Glycine max (L.) Merr.) showed good inhibitory activity against bacterial neuraminidase (BNA), which plays a pivotal role in the pathogenesis of a number of microbial diseases.

The aim of this study is to explore anti-inflammatory phytochemicals from B. chinensis based on the inhibition of pro-inflammatory enzyme, human neutrophil elastase (HNE) and anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage. Three stereoisomers of iridal-type triterpenoids (1–3) were isolated from the roots of B. chinensis and their stereochemistries were completely identified by NOESY spectra. These compounds were confirmed as reversible noncompetitive inhibitors against HNE with IC50 values of 6.8–27.0 µM. The binding affinity experiment proved that iridal-type triterpenoids had only a single binding site to the HNE enzyme. Among them, isoiridogermanal (1) and iridobelamal A (2) displayed significant anti-inflammatory effects by suppressing the expressions of pro-inflammatory cytokines, such as iNOS, IL-1β, and TNF-α through the NF-κB pathway in LPS-stimulated RAW264.7 cells. This is the first report that iridal-type triterpenoids are considered responsible phytochemicals for anti-inflammatory effects of B. chinensis.

Anti-melanogenesis effects of silymarin from milk thistle have been reported recently, but detailed tyrosinase inhibition properties of individual components have not been investigated. This study purported to substantiate tyrosinase inhibition and its mechanism based on a single metabolite. The responsible components for tyrosinase inhibition of target source were found out as flavonolignans which consist of isosilybin A (1), isosilybin B (2), silydianin (3), 2,3-dihydrosilychristin (4), silychristin A (5), silychristin B (6) and silybin (7), respectively. The isolated flavonolignans (1–7) inhibited both monophenolase (IC50 = 1.7–7.6 µM) and diphenolase (IC50 = 12.1–44.9 µM) of tyrosinase significantly. Their inhibitions were 10-fold effective in comparison with their mother skeletons (8–10). Inhibitory functions were also proved by HPLC analysis using N-acetyl- l -tyrosine as substrate. The predominant formation of Emet·I was confirmed from a long prolongation of lag time and a decrease of the static state activity of the enzyme. All tested compounds had a significant binding affinity to tyrosinase with KSV values of 0.06–0.27 × 104 L·mol−1, which are well correlated with IC50s. In kinetic study, all flavonolignan (1–7) were mixed type I (KI

The chromenone derivatives (1–4) from the root part of Flemingia philippinensis showed a significant inhibition against bacterial neuraminidase (NA) which plays a pivotal role in a cellular interaction including pathogenesis of bacterial infection and subsequent inflammation. The compounds 1 and 2 were the new compounds, philippin D (1) and philippin E (2). In particular, compounds (1–3) exhibited sub micromolar levels of IC50 values with 0.75, 0.54, and 0.07 μM. This is the first report that chromenone skeleton emerged as a lead structure of bacterial NA inhibition. In kinetic study, 8,8-diprenyl compounds displayed competitive inhibitory mode, whereas 4a,8-diprenyl ones showed noncompetitive behavior. It was manifested that all competitive inhibitors (1 and 2) were simple reversible slow-binding against bacterial NA. The binding affinities (KSV) of inhibitors to enzyme were agreement with their respective inhibitory potencies. Molecular docking data confirmed that the position of 3-methyl-2-butenyl substituent affects inhibitory mechanism against CpNanI. The tri-arginyl cluster of R266, R555, and R615 and D291 in NanI tightly interact with the competitive inhibitors.

Neutrophil elastases are deposited in azurophilic granules interspace of neutrophils and tightly associated with inflammatory ailments. The root barks of Artocarpus elasticus had a strong inhibitory potential against human neutrophil elastase (HNE). The responsible components for HNE inhibition were confirmed as alkylated flavones (2–4, IC50 = 14.8 ~ 18.1 μM) and dihydrobenzoxanthones (5–8, IC50 = 9.8 ~ 28.7 μM). Alkyl groups on flavone were found to be crucial functionalities for HNE inhibition. For instance, alkylated flavone 2 (IC50 = 14.8 μM) was 20-fold potent than mother compound norartocarpetin (1, IC50 > 300 μM). The kinetic analysis showed that alkylated flavones (2–4) were noncompetitive inhibition, while dihydrobenzoxanthones (5–8) were a mixed type I (KI KIS) inhibitors, which usually binds with free enzyme better than to complex of enzyme–substrate. Inhibitors and HNE enzyme binding affinities were examined by fluorescence quenching effect. In the result, the binding affinity constants (KSV) had a significant correlation with inhibitory potencies (IC50).

Xanthine oxidase is a frontier enzyme to produce oxidants, which leads to inflammation in the blood. Prenylated isoflavones from Flemingia philippinensis were found to display potent inhibition against xanthine oxidase (XO). All isolates (1&ndash, 9) inhibited XO enzyme with IC50 ranging 7.8~36.4 &mu, M. The most active isoflavones (2&ndash, 5, IC50 = 7.8~14.8 &mu, M) have the structural feature of a catechol motif in B-ring. Inhibitory behaviors were disclosed as a mixed type I mode of inhibition with KI &lt, KIS. Binding affinities to XO enzyme were evaluated. Fluorescence quenching effects agreed with inhibitory potencies (IC50s). The compounds (2&ndash, 5) also showed potent anti-LDL oxidation effects in the thiobarbituric acid-reactive substances (TBARS) assay, the lag time of conjugated diene formation, relative electrophoretic mobility (REM), and fragmentation of apoB-100 on copper-mediated LDL oxidation. The compound 4 protected LDL oxidation with 0.7 &mu, M in TBARS assay, which was 40-fold more active than genistein (IC50 = 30.4 &mu, M).

Intensive investigation of phytochemicals from edible Melicope glabra leaves provided a series of O-alkylated quercetins (1–13). The quercetin 1 bearing prenyl and methyl motif showed potent inhibition to human acetylcholinesterase (hAChE) with mixed type I mode, while quercetin was inactive. The position of methyl group was also a critical factor to hAChE inhibition: 1 (4′-O-methyl, IC50 = 12.7 μM) vs 2 (3′-O-methyl, IC50 = 119 μM). Inhibitory potency was doubly confirmed with the binding affinity (KSV) based on fluorescence quenching. O-Methyl groups on quercetin were observed to influence β-secretase (BACE1) inhibition. Thus, O-methylated quercetins (4–6) displayed potential inhibitions against BACE1 with IC50 values of 1.3, 4.1, and 14.1 μM, respectively. All compounds (3–6) have noncompetitive mode to BACE1. Additionally, all quercetin derivatives (1–13) had antioxidant potentials against different radical sources (ABTS, ORAC and FRAP). The UPLC-ESI-Q-TOF/MS indicated that the leaves part had promising metabolites towards hAChE and BACE1 inhibitions, which are the most predominant phytochemicals.

Human neutrophil elastase (HNE) has been linked to immune system functions, including inflammation, as well as the development of skin wrinkles, suggesting that HNE inhibitors have many practical applications. In this study, the methanol extract of Epimedium koreanum Nakai contained potent HNE inhibitory flavonoids (1–4) with IC 50 values of 6.06–125.80 μM. Prenyl groups within these flavonoids were critical for the inhibitory effects. For example, epimedokoreanin B (1) (IC 50 = 6.06 μM) showed 6-fold higher efficacy than that of its parent luteolin (IC 50 = 36.01 μM). A similar trend was observed for compound 2 (IC 50 = 6.28 μM) and its parent, apigenin (IC 50 = 37.94 μM). Lineweaver–Burk plots showed that the compounds exhibit mixed-type inhibition. In a detailed kinetic study, compound 1 was assigned to mixed type I and exhibited the greatest binding to the free enzyme (K I = 11.7 μM, K IS = 40.9 μM).

In the course of an investigation of human neutrophil elastase (HNE) associated with inflammation, the extract of the flower parts of Hypericum ascyron showed a significant influence to HNE. The responsible metabolites to HNE inhibition were found to be eight polyprenylated acylphloroglucinols, PPAPs (1–8) which showed IC50 ranges between 2.4 and 19.9 μM. This is the first report to demonstrate that PPAP skeleton exhibits potent HNE inhibition. The compounds 1–3 were characterized and newly named as ascyronone E (IC50 = 4.3 μM), ascyronone F (IC50 = 19.9 μM), ascyronone G (IC50 = 4.5 μM) based on 2D-NMR spectroscopic data. In the kinetic analysis of double reciprocal plots, all the compounds showed noncompetitive behaviors to HNE enzyme with the remaining of Km and the increase of Vmax. The binding affinity levels (KSV) by using fluorescence were sufficient to be able to prove that PPAPs (1–8) had compliant interaction with inhibitory potencies.

Genistein and daidzein are predominant phytoestrogens for an estrogen alternative due to their higher receptor binding affinity. The present study illustrated the effective method to produce isoflavone riched soybean leaves (IRSL). Notably, ethylene application to soybean leaves under dark condition led a distinctive increase in genistin, daidzin, malonylgenistin and malonyldaidzin, which raised to total 25,911 μg/g of isoflavones in comparison to control leaves (>200 μg/g). Genistin and daidzin derivatives were enhanced with 120-fold (123→14,996 μg/g) and 185-fold (59→10,916 μg/g), respectively. The changes in metabolites by ethylene were systematically identified by UPLC–ESI-TOF/MS to give successfully PLS-DA score and heatmap analysis. The identified nine isoflavones were markedly increased, whereas rest main metabolites, kaempferols and soyasaponins were not affected. Furthermore, in contrast to the control leaves, the IRSL extract showed stimulation of collagen synthesis and induced gene expressions, in particular COL1A1 and COL3A1, in human dermal fibroblast.

In this study, the inhibitory potential of bacterial neuraminidase (NA) was observed on the leaves of Epimedium koreanum Nakai, which is a popular ingredient in traditional herbal medicine. This study attempted to isolate the relevant, responsible metabolites and elucidate their inhibition mechanism. The methanol extraction process yielded eight flavonoids (1–8), of which compounds 7 and 8 were new compounds named koreanoside F and koreanoside G, respectively. All the compounds (1–8) showed a significant inhibition to bacterial NA with IC50 values of 0.17–106.3 µM. In particular, the prenyl group on the flavonoids played a critical role in bacterial NA inhibition. Epimedokoreanin B (compound 1, IC50 = 0.17 µM) with two prenyl groups on C8 and C5′ of luteolin was 500 times more effective than luteolin (IC50 = 85.6 µM). A similar trend was observed on compound 2 (IC50 = 0.68 µM) versus dihydrokaempferol (IC50 = 500.4 µM) and compound 3 (IC50 = 12.6 µM) versus apigenin (IC50 = 107.5 µM). Kinetic parameters (Km, Vmax, and Kik/Kiv) evaluated that all the compounds apart from compound 5 showed noncompetitive inhibition. Compound 5 was proven to be a mixed type inhibitor. In an enzyme binding affinity experiment using fluorescence, affinity constants (KSV) were tightly related to inhibitory activities.

F. philippinensis Merr. et Rolfe has been cultivated on a large scale and is widely consumed by local inhabitants as an important nutraceutical, especially against rheumatism which has a deep connection with antioxidants. In this study, a total of 18 different phenolic metabolite compounds in F. philippinensis were isolated and identified, and evaluated for their antioxidant and DNA damage protection potential. The antioxidant activity of the 18 identified compounds was screened using DPPH, ORAC, hydroxyl and superoxide radical scavenging assays. The antioxidant potential of the compounds was found to differ by functionality and skeleton. However, most compounds showed a good antioxidant potential. In particular, seven of the identified compounds, namely, compounds 2, 3, 6, 10, 11, 15 and 16, showed significant protective effects on pBR322 plasmid DNA against the mutagenic and toxic effects of Fenton’s reaction. The most active compound, compound 2, displayed a dose-dependent DNA damage protection potential in the range of 7.5~60.0 μM. The DNA damage protective effect of the identified compounds was significantly correlated with the hydroxyl radical scavenging activity. Compounds that exhibited effective (IC50 = 5.4~12.5 μg/mL) hydroxyl radical scavenging activity were found to be the ones with higher DNA damage protection potential.