Mei Lin Yang

Anti-inflammatory principles from Cordyceps sinensis.

In order to explore the anti-inflammatory principles of the mycelia of Cordyceps sinensis, the crude extract and partially purified fractions were examined for their inhibition of superoxide anion generation and elastase release. Further chemical investigation of the bioactive fractions has resulted in the identification of 50 compounds, including five constituents, cordysinins A-E (1-5), reported from a natural source for the first time. In addition, compounds were examined for their anti-inflammatory activity. 1-(5-Hydroxymethyl-2-furyl)-β-carboline displayed the most significant inhibition of superoxide anion generation and elastase release with IC50 values of 0.45±0.15 and 1.68±0.32 μM, respectively.

Synthesis, in vitro anti-inflammatory and cytotoxic evaluation, and mechanism of action studies of 1-benzoyl-β-carboline and 1-benzoyl-3-carboxy-β-carboline derivatives

In the present study, various 1-substituted and 1,3-disubstituted β-carboline derivatives were synthesized by a modified single-step Pictet-Spengler reaction. The compounds were examined for cytotoxicity and anti-inflammatory activity, as measured by the inhibition of prostaglandin E(2) (PGE(2)) production and nitric oxide (NO) production. While only two compounds (28 and 31) showed marginal cytotoxicity against four human cancer cell lines, most of the tested compounds exhibited potent inhibitory activity of both NO and PGE(2) production. Moreover, compounds 6 and 16 significantly reduced the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase 2 (COX2), suggesting that β-carboline analogs can inhibit NO and PGE(2) production at the translational level. In addition, several of the β-carboline derivatives (1, 2, 4-8, 11, 13, 22, 25, 27, 31, and 41-43) displayed significant inhibitory activity of superoxide anion (O(2)(·-)) generation or elastase release compared to the reference compound, with 6 being the most potent. N-Formyl-L-methionyl-phenylalanine (FMLP)-induced phosphorylation of c-JunN-terminal kinase (JNK) and protein kinase B (AKT) were also inhibited by 6, suggesting that it suppresses human neutrophil functions by inhibiting the activation of JNK and AKT signaling pathways. Therefore, the synthetic 1-benzoyl-3-carboxy β-carboline analogs may have great potential to be developed as anti-inflammatory agents.

Anti-inflammatory Diterpenoids from Croton tonkinensis

Phytochemical investigation of the methanolic extract of Croton tonkinensis afforded two known kauranes (1, 2), eight new ent-kauranes (3-10), and 16 known ent-kaurane-type diterpenoids (12-27). In addition, 30 known compounds were identified by comparison of their physical and spectroscopic data with reported data. Among the isolated compounds, ent-18-acetoxykaur-16-en-15-one (20) displayed the most significant inhibition of superoxide anion generation and elastase release.

Chemical constituents from Abutilon indicum

The investigation on the chemical constituents of the whole plant of Abutilon indicum has resulted in the isolation of two new compounds, abutilin A (1) and (R)-N-(1′-methoxycarbonyl-2′-phenylethyl)-4-hydroxybenzamide (2), as well as 28 known compounds. The structures of the two new compounds were established on the basis of the spectroscopic analysis, and the known compounds were identified by comparison of their spectroscopic and physical data with those reported in the literature.

Chemical Constituents from the Fruits of Forsythia suspensa and Their Antimicrobial Activity

Lignans and phenylethanoid glycosides purified from Forsythia suspensa were reported to display various bioactivities in the previous literature, including the antimicrobial activity. Therefore, the present research is aimed to purify and identify the chemical constituents of the methanol extracts of fruits of F. suspensa. The methanol extracts of fruits of F. suspensa were fractionated and further purified with the assistance of column chromatography to afford totally thirty-four compounds. Among these isolates, 3β-acetoxy-20α-hydroxyursan-28-oic acid (1) was reported from the natural sources for the first time. Some of the purified principles were subjected to the antimicrobial activity examinations against Escherichia coli to explore new natural lead compounds.

Chemical constituents from the leaves of Annona reticulata and their inhibitory effects on NO production.

In the present study, the chemical investigation of the leaves of Annona reticulata has resulted in the identification of nine compounds, including annonaretin A, (1), a new triterpenoid. The purified compounds were subjected to the examination of their effects on NO inhibition in LPS-activated mouse peritoneal macrophages and most of them exhibited significant NO inhibition, with IC50 values in the range of 48.6 ± 1.2 and 99.8 ± 0.4 μM.

Chemical constituents of the leaves of glochidion obliquum and their bioactivity

A new flavonoid glycoside, globlin A (1), and eleven known compounds were isolated from methanolic extracts of the leaves of Glochidion obliquum. The structure of this new compound was established with a combination of 2D NMR techniques (COSY, NOESY, HMQC and HMBC) and HR-ESI-MS analyses. Chemical structures of the other known compounds were identified by comparison of their spectroscopic and physical data with those reported in the literature. Some of the isolates were examined for their bioactivities. Among the tested compounds, rotundic acid (4) displayed significant cytotoxicity and anti-inflammatory activities.

Chemical constituents from the leaves of Xylopia poilanei and their bioactivity

A new flavonoid glycoside, xylopoillin A (1), and nine known compounds were isolated from the methanolic extracts of the leaves of Xylopia poilanei. The structure of this new compound was completely elucidated using a combination of 2D NMR techniques (COSY, NOESY, HMQC and HMBC) and HR-ESI- MS analyses. The other chemical structures of known compounds were identified by comparison of their spectroscopic and physical data with those reported in the literature.

Triterpenoids and steroids from ganoderma mastoporum and their inhibitory effects on superoxide anion generation and elastase release

The methanol extracts of the fruiting bodies of Ganoderma mastoporum collected in Vietnam was purified to afford eight compounds, including three triterpenoids and five steroids. The purified compounds were examined for their inhibitory effects against superoxide anion generation and elastase release. Among the tested compounds, ergosta-4,6,8(14),22-tetraen-3-one (3) exhibited the most significant inhibition towards superoxide anion generation and elastase release with IC50 values of 2.30 ± 0.38 and 1.94 ± 0.50 µg/mL, respectively.

Flavonoids from the Fruits of Desmos cochinchinesis var. fulvecens and Their Inhibitory Effects on No Production

The genus Desmos (Annonaceae) is widely distributed in Southern Asia, including India, Ceylon, Myanmar, Thailand, Indochina, the Philippines, and Malaysia [1]. Among these, various species are native to northern Vietnam and reported to contain flavonoids and alkaloids [2–4]. In our continuous program aimed to study the bioactive principles from this plant in Vietnam, the fruits of D. cochinchinesis var. fulvecens Ban. were selected as the target due to its NO inhibiting potential in our preliminary bioassay (data not shown). Air-dried fruits of D. cochinchinesis var. fulvecens were powdered and extracted by methanol under reflux. Using a combination of conventional chromatographic techniques, we obtain a total of 16 compounds, including five flavones, oroxylin A (1) [5], mosloflavone (2) [6], isounonal (3) [7], unonal (4) [7], and desmosflavone (5) [8]; five dihydroflavones, demethoxymatteucinol (6) [9], 7-demethyllaridal (7) [10], cochinine A (8) [11], 5,6-dihydroxy-7-methoxydihydroflavone (9) [2], and 5-hydroxy-7-methoxy-6,8-dimethylflavanone (10) [12]; two flavanes, 8-formyl-7-hydroxy-4 ,5-dimethoxy-6methylflavane (11) [13] and 8-formyl-4,7-dihydroxy-5-methoxy-6-methylflavane (12) [14]; one dihydrochalcone, 2 ,6 -dihydroxy-4 -methoxydihydrochalcone (13) [15]; one benzenoid, benzoic acid (14) [16]; and two steroids, mixture of -sitosterol (15) and stigmasterol (16) [17]. These compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature. Among these isolated compounds, 3–8 and 11 were purified in larger quantities and subjected to bioactivity examinations.