Divergent Syntheses of (-)-Chicanine, (+)-Fragransin A2, (+)-Galbelgin, (+)-Talaumidin, and (+)-Galbacin via One-Pot Homologative γ-Butyrolactonization

In this study, the divergent syntheses of (-)-chicanine, (+)-fragransin A2, (+)-galbelgin, (+)-talaumidin, and (+)-galbacin are detailed. In this approach, an early-stage modified Kowalski one-carbon homologation reaction is utilized to construct the central γ-butyrolactone framework with the two necessary β,γ-vicinal stereogenic centers. The two common chiral γ-butyrolactone intermediates were designed to be capable for assembling five different optically active tetrahydrofuran lignans from commercially available materials in a concise and effective divergent manner in five to eight steps. These five syntheses are among the shortest and highest-yielding syntheses reported to date.

Amides, Isoquinoline Alkaloids and Dipeptides from the Aerial Parts of Piper mullesua

One undescribed amide, pipermullesine A, two undescribed isoquinoline alkaloids, pipermullesines B and C, and six undescribed dipeptides, pipermullamides A-F, along with 28 known compounds, were isolated from the aerial parts of Piper mullesua. The structures of the undescribed compounds were elucidated based on the analysis of 1D and 2D NMR and MS data. Furthermore, the structures of pipermullesines A-C were confirmed by single crystal X-ray diffraction analysis. All isolates were evaluated for inhibitory activity against platelet aggregation induced by thrombin (IIa) or platelet-activating factor (PAF). (-)-Mangochinine, pellitorine, and (2E,4E)-N-isobutyl-2,4-dodecadienamide showed weak inhibitory activity against rabbit platelet aggregation induced by PAF, with IC50 values of 470.3 µg/mL, 614.9 µg/mL, and 579.7 µg/mL, respectively.

Flavonoids from Machilus japonica stems and their inhibitory effects on LDL oxidation

Stems of Machilus japonica were extracted with 80% aqueous methanol (MeOH) and the concentrated extract was successively extracted with ethyl acetate (EtOAc), normal butanol (n-BuOH), and water. Six flavonoids were isolated from the EtOAc fraction: (+)-taxifolin, afzelin, (−)-epicatechin, 5,3'-di-O-methyl-(−)-epicatechin, 5,7,3'-tri-O-methyl-(−)-epicatechin, and 5,7-di-O-methyl-3',4'-methylenedioxyflavan-3-ol. The chemical structures were identified using spectroscopic data including NMR, mass spectrometry and infrared spectroscopy. This is the first report of isolation of these six compounds from M. japonica. The compounds were evaluated for their diphenyl picryl hydrazinyl scavenging activity and inhibitory effects on low-density lipoprotein oxidation. Compounds 1 and 3–6 exhibited DPPH antioxidant activity equivalent with that of ascorbic acid, with half maximal inhibitory concentration (IC₅₀) values of 0.16, 0.21, 0.17, 0.15 and 0.07 mM, respectively. The activity of compound 1 was similar to the positive control butylated hydroxytoluene, which had an IC₅₀ value of 1.9 µM, while compounds 3 and 5 showed little activity. Compounds 1, 3, and 5 exhibited LDL antioxidant activity with IC₅₀ values of 2.8, 7.1, and 4.6 µM, respectively.

Four new lignans from Schisandra sphenanthera

Three new 7,8-secolignans, schisandlignans A-C (1, 2, and 4), one new dibenzocyclooctadiene lignan, schisandlignan D (5), together with nine known lignans 3',4'-dimethoxybenzoic acid (3″,4″-dimethoxyphenyl)-2-methyl-3-oxobutyl ester (3), gomisin J (6), rubrisandrin A(1b) (7), interiotherin B (8), schisantherin D (9), ( - )-machilusin (10), ganschisandrine (11), henricine A (12), and (+)-1-hydroxy pinoresinol (13), were isolated from the rattan of Schisandra sphenanthera. Their structures were determined by analysis of 1D and 2D NMR spectroscopic data.

Composition, Antioxidant and Antimicrobial Activities of the Leaf Essential Oil of Machilus Japonica from Taiwan

The chemical composition, and antioxidant and antimicrobial activities of the essential oil isolated from the leaf of Machilus japonica from Taiwan have been investigated. The essential oil from the fresh leaves was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. A total of 97 compounds were identified, representing 100% of the oil. The main components identified were α-phellandrene (14.5%), α-pinene (12.8%), thymol (12.6%), β-pinene (8.3%), α-terpineol (6.5%) and carvacrol (6.0%). The antioxidant activity of the oil was tested by the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging capability test. The results showed that the IC50 was 51.8 μg/mL. The antimicrobial activity of the oil was tested by the disc diffusion and micro-broth dilution methods against ten microbial species. The oil exhibited strong growth suppression against Gram-positive bacteria and yeast, with inhibition zones of 48~54 mm and MIC values of 16.12~32.25 μg/mL, respectively. For the antioxidant and antimicrobial activities of the oil, the active source compounds were determined to be thymol and carvacrol.

Chemical constituents from the leaves of Machilus zuihoensis Hayata var. mushaensis (Lu) Y.C. Liu

One new lignan, machilolin-A (1), was isolated from the leaves of Machilus zuihoensis Hayata var. mushaensis (Lu) Y. C. Liu (Lauraceae), together with three known compounds, vanillin (2), beta-sitosterol (3) and stigmasterol (4). The structure of 1 was elucidated based on chemical analysis and spectral methods (IR, 1D and 2D NMR, HR-FAB-MS, EI-MS).

Lignans with anti-HIV activity from Schisandra propinqua var. sinensis

Fourteen new lignans, tiegusanins A-N (1-14), together with 13 known compounds were isolated from the aerial parts of Schisandra propinqua var. sinensis. The structures and absolute configurations of 1-13 were established using a combination of spectroscopic techniques. Compound 14 was obtained as a racemate. When evaluated for inhibitory activity against HIV-1, tiegusanin G (7) showed anti-HIV-1 activity with an EC(50) value of 7.9 microM and a therapeutic index (TI) of more than 25.

Stereoselective synthesis of tetrahydrofuran lignans via BF(3) x OEt(2)-promoted reductive deoxygenation/epimerization of cyclic hemiketal: synthesis of (-)-odoratisol C, (-)-futokadsurin A, (-)-veraguensin, (+)-fragransin A(2), (+)-galbelgin, and (+)-talaumidin

A versatile route to the synthesis of 2,5-diaryl-3,4-dimethyltetrahydrofuran lignans, (-)-odoratisol C (1), (-)-futokadsurin A (2), (-)-veraguensin (3), (+)-fragransin A2 (4), (+)-galbelgin (5), and (+)-talaumidin (6), is described. Central to the synthesis of the lignans is BF(3) x OEt(2)-promoted deoxygenation/epimerization of the hemiketal 9a followed by stereoselective reduction of the oxocarbenium ion intermediates 8a,b.

Neolignans from Piper futokadsura and Their Inhibition of Nitric Oxide Production

From a MeOH extract of the aerial part of Piper futokadsura, the tetrahydrofuran lignans, futokadsurin A [(7S,8S,7'S,8'R)-3,4,3'-trimethoxy-4'-hydroxy-7,7'-epoxylignan], futokadsurin B [(7R,8R,7'R,8'S)-3,4-dimethoxy-3',4'-methylenedioxy-7,7'-epoxylignan], and futokadsurin C [(7R,8R,7'S,8'S)-3,4-methylenedioxy-3',4'-dimethoxy-7,7'-epoxylignan] were isolated, together with nine known neolignans. In addition, L-tryptophan, pellitorine, phytol, elemicin, and 1,2,4-trimethoxyphenyl-5-aldehyde were isolated. The structures of the new compounds were elucidated using spectroscopic methods. These lignans inhibited nitric oxide production by a murine macrophage-like cell line (RAW 264.7), which was activated by lipopolysaccharide and interferon-gamma.

Antioxidant lignans from Larrea tridentata

Three lignans, (7S,8S,7'S,8'S)-3,3',4'-trihydroxy-4-methoxy-7,7'-epoxylignan, meso-(rel 7S,8S,7'R,8'R)-3,4,3',4'-tetrahydroxy-7,7'-epoxylignan, and (E)-4,4'-dihydroxy-7,7'-dioxolign-8(8')-ene, together with 10 known compounds, were isolated from the leaves of Larrea tridentata. The structures of the new compounds were determined primarily from 1D and 2D NMR spectroscopic analysis. Their antioxidant activities against intracellular reactive oxygen species were evaluated in HL-60 cells.

Trypanocidal constituents in plants 1. Evaluation of some Mexican plants for their trypanocidal activity and active constituents in Guaco, roots of Aristolochia taliscana

Crude extracts of Mexican medicinal plants were screened for trypanocidal activity against Trypanosoma cruzi, which is the etiological agent for Chagas' disease, one of the most serious protozoan diseases in Latin America. There were 43 kinds of methanolic and other organic extracts from 39 plants which were examined by the preliminary screening test to see immobilization of epimastigotes of T. cruzi in vitro. Eighteen of them showed activity at the concentration of 2 mg/ml after incubation for 2 h, while 13 showed activity at the concentration of 1 mg/ml after incubation for 48 h. Among them, the MeOH extract of roots of Aristolochia taliscana (Aristolochiaceae), locally known as "Guaco," immobilized all the epimastigotes even at lower concentration of 0.5 mg/ml (48 h). In order to identify principal compounds for this activity, the MeOH extract of Guaco was subjected to bioassay-guided fractionation. From the active fractions, four neolignans, eupomatenoid-7 (1), licarin A (2), eupomatenoid-1 (5) and licarin B (6), and two lignans, austrobailignan-7 (3) and fragransin E1 (4) were isolated. Compounds 1-4 immobilized all the epimastigotes at the minimum concentration of 25-75 microg/ml after incubation for 48 h, while compounds 5 and 6 were inactive. Corresponding concentration of gossypol, berberine chloride and harmine was 280 microg/ml, 300 microg/ml and >500 microg/ml, respectively.