Tran Manh Hung

Antioxidant activities of coumarins from Korean medicinal plants and their structure-activity relationships.

The aim of this work was to study the structure–activity relationships of the antioxidant activity of natural coumarins isolated from four Korean medicinal plants (1–17) and four purchased coumarins (18–21). The free radical scavenging and lipid peroxidation assays revealed that five phenolic coumarins, scopoletin (1), aesculetin (2), fraxetin (3), umbelliferone (18) and daphnetin (19), possessed considerable antioxidant activities. The coumarins having a catechol group, 2, 3 and 19, showed significant free radical scavenging activity and inhibitory effects on lipid peroxidation, indicating that the catechol group significantly contributed to the antioxidant activities of coumarins. In contrast, the sugar moiety markedly reduced the activities of coumarin glycosides. The results also demonstrate that the α‐pyrone ring of coumarins significantly enhanced the capacity of inhibiting oxidative reactions of coumarins. Copyright

Steroids and triterpenes from the fruit bodies of Ganoderma lucidum and their anti-complement activity.

To determine the anti-complement activity of natural triterpenes, chromatographic separation of the EtOAc-soluble fraction from the fruiting body of Ganoderma lucidum led to the isolation of three steroids and five triterpenoids. They were identified as ergosterol peroxide (1), ergosterol (2), genoderic acid Sz (3), stella sterol (4), ganoderic aic C1 (5), ganoderic acid A (6), methyl ganoderate A (7), and lucidenic acid A (8) based on spectroscopic evidence and physicochemical properties. These compounds were examined for their anti-complement activity against the classical pathway of the complement system. Compounds 2 and 3 showed potent anti-complement activity with IC50 values of 52.0 and 44.6 µM, respectively. Compound 1 exhibited significant inhibitory activity with an IC50 value of 126.8 µM, whereas compounds 4–8 were inactive. Our findings suggested that in addition to the ketone group at C-3, the Δ7(8), Δ9(11)-lanostadiene type triterpene also plays an important role in inhibiting the hemolytic activity of human serum against erythrocytes.

Homoisoflavonoid derivatives from the roots of Ophiopogon japonicus and their in vitro anti-inflammation activity.

Three new homoisoflavonoids (1-3) were isolated from the roots of Ophiopogon japonicus (Liliaceae). The structures of new metabolites were determined on the basis of spectroscopic analyses including 2D NMR. The anti-inflammatory activities of new compounds (1-3) were investigated by their effects on the release of the inflammatory chemokine eotaxin, stimulated by IL-4 and the combination of IL-4 and TNF-alpha in BEAS-2B cells, which mimics the in vivo conditions in bronchial allergic asthma.

Labdane‐type diterpenoids from Leonurus heterophyllus and their cholinesterase inhibitory activity

In the course of screening plants used in natural medicines as memory enhancers, a 70% ethanol extract of the aerial parts of Leonurus heterophyllus showed significant AChE inhibitory activity. Bioassay‐guided fractionation and repeated column chromatography led to the isolation of a new labdane‐type diterpenoids (1), named leoheteronin F, and six known compounds (2–7). The chemical structures of isolated compounds were elucidated based on extensive 1D and 2D NMR spectroscopic data. The isolates 1–7 were investigated in vitro for their anticholinesterase activity using mouse cortex AChE enzyme. Leoheteronin A (5) and leopersin G (7), which possess a 15,16‐epoxy group at the side chain, were found to be potent in the inhibition of AChE. Copyright

Inhibitory effect on NO production of triterpenes from the fruiting bodies of Ganoderma lucidum.

Four new lanostane triterpenes, butyl lucidenate P (1), butyl lucidenate D(2) (2), butyl lucidenate E(2) (3) and butyl lucidenate Q (4) along with 11 known compounds (5-15) were isolated from the fruiting bodies of Ganoderma lucidum. Their chemical structures were established mainly by 1D and 2D NMR techniques and mass spectrometry. Their anti-inflammatory activity was evaluated against LPS-induced NO production in macrophage RAW 264.7 cells. Compounds 1, 3, 4, 9, 10 and 15 showed inhibitory potency with IC(50) values of 7.4, 6.4, 4.3, 9.4, 9.2 and 4.5 μM, respectively. Compounds 1, 3 and 15 dose-dependently reduced the LPS-induced iNOS expressions. Preincubation of cell with 1, 3 and 15 significantly suppressed LPS-induced expression of COX-2 protein.

Cholinesterase inhibitors from Cleistocalyx operculatus buds

Five flavonoids, myricetin-3′-methylether 3-O-β-d-galactopyranoside (1), myricetin-3′,5′-dimethylether 3-O-β-d-galactopyranoside (2), quercetin (3), kaempferol (4), and tamarixetin (5) were isolated from the buds of Cleistocalyx operculatus (Myrtaceae). The chemical structures of these compounds were determined on the basis of spectroscopic analyses, including 2D NMR. Their anti-Alzheimer effects were evaluated via acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity assays. All five compounds 1–5 showed potential inhibitory activities against AChE with IC50 values of 19.9, 37.8, 25.9, 30.4 and 22.3 μM, respectively, while compounds 1, 3, 4 and 5 also possessed BChE inhibitory activity with IC50 values of 152.5, 177.8, 62.5, and 160.6 μM, respectively.

Simultaneous determination of bioactive flavonoids in some selected Korean thistles by high-performance liquid chromatography.

In order to facilitate the quality control of some selected Korean thistles (Cirsii Herb), Cirsium japonicum var ussuriense, C. japonium var spinosissimum, C. setidens, C. pendulum, C. nipponicum, Carduus crispus, and Breea segetum, a simple, accurate and reliable high performance liguid chromatography method was developed for the simultaneous determination of the six flavonoids: luteolin 5-O-glucoside (1), luteolin 7-O-glucoside (2), hispidulin 7-O-neohesperidoside (3), luteolin (4), pectolinarin (5), and apigenin (6), which were selected as the chemical markers of the thistles. Separation was achieved on an Agilent Eclipse XDB-C18 column with a gradient solvent system of 0.1% trifluoroacetic acid aqueous-methanol at a flow-rate of 1.0 mL/min and detected at 254 nm. All six calibration curves showed good linearity (R2 > 0.991). The method was reproducible with intra- and inter-day variations of less than 6%. The recoveries were in the range of 90.01–100.05%. This analysis method was successfully utilized to quantify the six flavonoids in the 22 batches of the thistles. The results demonstrated that this method is simple, reliable and suitable for the quality control of this medicinal herb.

Anti-inflammatory activity of phenolic compounds from the whole plant of Scutellaria indica.

Six new phenolics, scutellariosides A-F (1-3, 5-6, and 8), together with six known compounds (4, 7, 9-12) were isolated from the whole plant of Scutellaria indica (Labiatae). The chemical structures of these compounds were determined by spectroscopic analyses including 2D NMR. Their anti-inflammatory activities were evaluated against LPS-induced NO production in macrophage RAW 264.7 cells. Among them, compounds 10-12 had inhibitory effects with IC50 values ranging from 7.2 to 27.8μM. Compound 12 reduced LPS-induced iNOS expression in a dose-dependent manner.

Fatty acid synthase inhibitory activity of dibenzocyclooctadiene lignans isolated from Schisandra chinensis

Inhibition of fatty acid synthase (FAS) has been proposed to be a new therapeutic target for the treatment of cancer and obesity. In our preliminary screening study on the FAS inhibitory activity, a n‐hexane soluble fraction prepared from the fruit of Schisandra chinensis (Schisandraceae) was found to inhibit FAS activity at 100 μg/mL. Nine dibenzocyclooctadiene lignans were isolated from the active fraction and were evaluated for their inhibitory effect on FAS for the first time. The compounds possessing a benzoyl or tigloyl group in the dibenzocyclooctadiene skeleton entirely inhibited the FAS activity in a dose dependent manner. The findings may be partially related to the anticancer effect of the medicinal plant, suggesting a further study on the anticancer potential of dibenzocyclooctadiene derivatives. Copyright

Cassaine diterpene alkaloids from Erythrophleum fordii and their anti-angiogenic effect

Angiogenesis plays a critical role in embryonic development and various physiological processes. However, excessive angiogenesis is associated with several pathological conditions including cancer. Angiogenesis is closely related to tumor growth, invasion and metastasis, and is considered a prime target for anticancer therapy. In this study, two new mono cassaine diterpenoid amides (1, 5) and four known compounds (2-4, 6) were isolated from the bark of Erythrophleum fordii (Leguminosae). Their chemical structures were established mainly by 1D and 2D NMR techniques and mass spectrometry. The effects of isolates on endothelial tube formation on Matrigel were investigated. Among them, compound 3 was found to have the most potent inhibitory effect on the capillary-like structure formation of human umbilical vein endothelial cells (HUVECs).