Yu-Chi Lin

New and bioactive lignans from the fruits of Schisandra sphenanthera.

Phytochemical investigation of the ethanol extract from the fruits of Schisandra sphenanthera has resulted in isolation of seven new oxygenated lignans (1-7), in addition to 11 known compounds (8-18). Their structures were determined on the basis of 2D-NMR (COSY, HMQC, HMBC and NOESY) analyses. The isolated components were evaluated with a reporter gene assay that measures their anti-liver fibrosis activity. Compounds 1, 2, 4, 11, 13, 14 and 18 exhibited significant anti-inflammatory activity on HSC-T6 test.

Anti-liver fibrotic lignans from the fruits of Schisandra arisanensis and Schisandra sphenanthera

Three new polyoxygenated C(18)-dibenzocyclooctadiene lignans, arisanschinins M and N (1 and 2) and schisphenin A (3), together with eight related metabolites (4-11), were isolated from the fruits of Schisandra arisanensis and Schisandra sphenanthera, respectively. The structures of 1-3 were elucidated on the basis of extensive spectroscopic and 2D NMR (HSQC, HMBC, and NOESY) analyses. The configuration of the biphenyl moiety in the octadiene ring was determined by circular dichroism (CD). Compound 1 possessed an unprecedented 3-(1-hydroxypropan-2-yl)-3-methyl-1,4-dioxo-2-one lactonide ring system attaching at C-6/C-14. Pharmacological studies revealed that compounds 3, 4, 6, 7, and 10 exhibited significant anti-hepatic fibrosis activity, while 9 and 11 showed cytotoxicity against HSC-T6 cells. The biogenetic pathway for compound 1 was also proposed.

Asterolaurins A-F, xenicane diterpenoids from the Taiwanese soft coral Asterospicularia laurae.

Six new xenicane-type diterpenoids, designated as asterolaurins A-F (1-6), have been isolated from the organic extract of the soft coral Asterospicularia laurae, collected in southern Taiwan. Compounds 1-4 possess a xenicin skeleton with a 2-oxabicyclo[7.4.0]tridecane ring system, while 5 and 6 are xeniolide A-type compounds. The structures of the new secondary metabolites, including their configurations, were established on the basis of an extensive spectroscopic analysis, including 1D and 2D NMR (1H-1H COSY, HMQC, HMBC, and NOESY), and by comparison of their NMR data with those of the related compounds. The structure of asterolaurin A (1) was confirmed by X-ray diffraction analysis, and its absolute configuration was determined using the modified Moshers method. Asterolaurin A (1) exhibited moderate cytotoxicity against HepG2 cells with an IC50 of 8.9 microM, while asterolaurin D (4) showed potent inhibition of elastase release and superoxide anion generation in vitro.

Four New Briarane Diterpenoids from Taiwanese Gorgonian Junceella fragilis

Four new 8-hydroxybriarane diterpenoids, frajunolides P–S (1–4), together with umbraculolide A, juncenolide C, junceellonoid A and juncin R, were isolated from the acetone extract of the gorgonian Junceella fragilis, collected from the southeast coast of Taiwan. Compound 1 contains an unusual pivaloyloxy group at C-2, while 3 is a rare compound having a chlorine atom on the olefinic carbon (C-6). The structures of the isolated compounds were established by extensive spectroscopic analysis, including 1D- and 2D-NMR, as well as HRMS data. Compound 1 was further confirmed by X-ray crystallographic analysis. In the anti-inflammatory test, compounds 1 and 2 exhibited moderate inhibition on superoxide anion generation and elastase release by human neutrophils in response to formylmethionylleucyl-phenylalanine/dihydrocytochalasin B (fMLP/CB).

Dibenzocyclooctadiene lignans from Kadsura philippinensis

Lignans with the dibenzocyclooctadiene skeleton, kadsuphilols I-L, and one C(19)-homolignan, kadsuphilol M, were isolated by chromatographic fractionation of an ethyl acetate extract of the aerial parts of Kadsura philippinensis. Their structures were elucidated through extensive spectroscopic methods, including HRESIMS and 2D NMR experiments (HMQC, COSY and HMBC). The stereochemistry at the chiral centers and the biphenyl moist, were determined using NOESY, as well as analysis of CD spectra, respectively. The relative configuration of heteroclitin J was confirmed by single crystal X-ray crystallographic analysis. The in vitro radical-scavenging activities of these compounds by using DPPH were evaluated.

New Bioactive Chromanes from Litchi chinensis

Seven new δ-tocotrienols, designated litchtocotrienols A-G (1-7), together with one glorious macrocyclic analogue, macrolitchtocotrienol A (8), and one new meroditerpene chromane, cyclolitchtocotrienol A (9), were isolated from the leaves of Litchi chinensis. Their structures were mainly determined by extensive spectroscopic analysis, and their biological activities were evaluated by cytotoxicity against human gastric adenocarcinoma cell lines (AGS, ATCC CRL-1739) and hepatoma carcinoma cell line (HepG2 2.2.1.5). The structure-activity relationship of the isolated compounds was also discussed.

New verticillane diterpenoids from Cespitularia taeniata.

Chemical investigation of Cespitularia taeniata has led to the isolation of three new verticillanes, cespitulins E–G (1–3, resp.). The structures of these compounds were elucidated by spectroscopic analysis, especially HR‐MS and 2D‐NMR techniques. Compound 1 possesses a rare norverticillane skeleton with two adjacent OH groups at C(5) and C(6), while the seco‐compound 2 with an aldehyde group at C(9) results from an unusual bond cleavage between C(9) and C(10). Pharmacological studies revealed that compound 3 exhibited significant activities on superoxide‐anion generation and elastase release by human neutrophils in response to FMLP/CB. A plausible biogenetic pathway for compound 2 is also discussed.

Hyperinakin, a new anti-inflammatory phloroglucinol derivative from Hypericum nakamurai

Phytochemical investigation of Hypericum nakamurai (Masamune) Robson has led to the isolation of three phloroglucinol derivatives 1–3. The structures of these compounds were determined by the analysis of their spectroscopic data (IR, mass and UV), and by the application of 1-D and 2-D-NMR techniques. Hyperinakin (1) is a new compound. The anti-inflammatory activities of compounds 1–3 were also tested and evaluated. A biogenetic pathway for compounds 1–3 was also proposed.

Biological Activity of Oleanane Triterpene Derivatives Obtained by Chemical Derivatization

Nine new derivatives of oleanane triterpenoids isolated from Fatsia polycarpa Hayata were synthesized through chemical transformations. Acetylation was effected by reaction with acetic anhydride in pyridine to afford compounds 1–5, while compound 6 was obtained using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl) in CH2Cl2. The others derivatives 7–9 were obtained in reactions of the corresponding triterpenoids with EDC·HCl, 4-N,N-dimethylaminopyridine hydrochloride and 4-N,N-dimethylaminopyridine in CH2Cl2. The structures of 1–9 were elucidated from extensive spectroscopic and HRESIMS data, while the structure of 9 was further confirmed by X-ray diffraction analysis. The cytotoxic, anti-hepatitis B virus (HBV), antibacterial, hypoglycaemic and Wnt signaling activities of these derivatives were evaluated in vitro.

New Cytotoxic Prostanoids from Taiwanese Soft Coral Clavularia viridis

Chemical investigation of the AcOEt/MeOH extract of Clavularia viridis collected in Taiwan has afforded four new prostanoids, named claviridins A–D (1–4, resp.). The structures of compounds 1–4 were determined on the basis of 1D‐ and 2D‐NMR techniques, including COSY, HMQC, HMBC, and NOESY experiments. Pharmacological studies revealed that compounds 1–4 exhibited potent cytotoxicity against human cancer cells.