Wen-Li Mei

A New Cytotoxic Pregnanone from Calotropis gigantea

A new pregnanone, named calotropone (1), was isolated from the EtOH extract of the roots of Calotropis gigantea L. together with a known cardiac glycoside. The structures were elucidated by a study of their physical and spectral data. Compounds 1 and 2 displayed inhibitory effects towards chronic myelogenous leukemia K562 and human gastric cancer SGC-7901 cell lines.

2-(2-phenylethyl)chromone derivatives from Chinese agarwood induced by artificial holing.

Three new 2-(2-phenylethyl)chromone derivatives (1-3), together with thirteen known ones (4-16), were isolated from the EtOAc extract of Chinese agarwood induced by artificial holing, originating from Aquilaria sinensis (Lour.) Gilg (Thymelaeaceae). The chemical structures of the new compounds were identified by spectroscopic techniques (UV, IR, MS, 1D and 2D NMR). Compounds 1, 6, 15 and 16 exhibited inhibitory effects on Staphylococcus aureus, and compounds 15 and 16 showed inhibitory effects on Ralstonia solanacearum. Compounds 1-3, 7, 9, 11, 12, 15 and 16 exhibited acetylcholinesterase inhibitory activity. A possible biogenetic pathway of compounds 1-16 was proposed to show the relationships between diepoxy-tetrahydro-2-(2-phenylethyl)chromones, epoxy-tetrahydro-2-(2-phenylethyl) chromones, tetrahydro-2-(2-phenylethyl)chromones, and 2-(2-phenylethyl)chromones of the flidersia type, the four main types of 2-(2-phenylethyl)chromones found in agarwood, on the basis of their appearances in different stage of agarwood formation.

Two new 2-(2-phenylethyl)chromones from Chinese eaglewood

Two new 2-(2-phenylethyl)chromones, (5S *,6R *,7S *)-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (1) and (5S *,6R *,7R *)-5,6,7-trihydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (2), were isolated from the Chinese eaglewood of Aquilaria sinensis (Lour.) Gilg. Their structures were established by detailed MS and NMR spectroscopic analysis, as well as comparison with the literature data.

Two New Types of Bisindole Alkaloid from Trigonostemon lutescens

Six unprecedented bisindole alkaloids, trigolutesins A and B (1-2) with a unique polycyclic skeleton and trigolutes A-D (3-6) with another polycyclic skeleton, were isolated from the twigs of Trigonostemon lutescens. Their structures and relative configurations were elucidated by spectroscopic data and single-crystal X-ray diffraction crystallography. Trigolutesin A (1) showed weak AChE inhibitory activity.

A New 2-(2-Phenylethyl)Chromone from Chinese Eaglewood

A new 2-(2-phenylethyl)chromone, 5,6,7,8-tetrahydroxy-2-(3-hydroxy-4-methoxyphenethyl)-5,6,7,8-tetrahydro-4H-chromen-4-one (1) was isolated from the Chinese eaglewood [Aquilaria sinensis (Lour.) Gilg]. Its structure was established by detailed MS and NMR spectroscopic analysis, as well as comparison with literature data.

Antioxidant activity of papaya seed extracts.

The antioxidant activities of the ethanol, petroleum ether, ethyl acetate, n-butanol and water extract fractions from the seeds of papaya were evaluated in this study. The ethyl acetate fraction showed the strongest DPPH and hydroxyl free radical-scavenging activities, and its activities were stronger than those of ascorbic acid and sodium benzoate, respectively. The n-butanol fraction demonstrated the greatest ABTS+ radicals scavenging activity. The ethyl acetate fraction and the n-butanol fraction not only showed higher antioxidant activities than the petroleum ether fraction, water fraction and ethanol fraction, but also showed higher superoxide anion and hydrogen peroxide radicals scavenging activities than those of the other extract fractions. The high amount of total phenolics and total flavonoids in the ethyl acetate and n-butanol fractions contributed to their antioxidant activities. The ethyl acetate fraction was subjected to column chromatography, to yield two phenolic compounds, p-hydroxybenzoic acid (1) and vanillic acid (2), which possessed significant antioxidant activities. Therefore, the seeds of papaya and these compounds might be used as natural antioxidants.

Five new eudesmane-type sesquiterpenoids from Chinese agarwood induced by artificial holing.

Five new eudesmane-type sesquiterpenoids (1-5), along with six known ones (6-11), were isolated from Chinese agarwood induced by artificial holing originating from Aquilaria sinensis (Lour.) Gilg (Thymelaeaceae). The structures of the new sesquiterpenoids were established by spectroscopic methods including UV, IR, MS, 1D, and 2D NMR. Compounds 1, 3, 6 and 7 exhibited antibacterial activities against both Staphylococcus aureus and Ralstonia solanacearum, and compound 5 only showed an inhibitory activity towards S. aureus. Compounds 1, 6, 7 and 10 showed weak acetylcholinesterase inhibitory activity.

Meroterpenes from Endophytic Fungus A1 of Mangrove Plant Scyphiphora hydrophyllacea

Four new meroterpenes, guignardones F–I (1–4), together with two known compounds guignardones A (5) and B (6) were isolated from the endophytic fungus A1 of the mangrove plant Scyphiphora hydrophyllacea. Their structures and relative configurations were elucidated by spectroscopic data and single-crystal X-ray crystallography. A possible biogenetic pathway of compounds 1–6 was also proposed. All compounds were evaluated for inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus.

A new 2-(2-phenylethyl)chromone glycoside in Chinese agarwood “Qi-Nan” from Aquilaria sinensis

Abstract A new 2-(2-phenylethyl)chromone glycoside, 2-[2-(4-glucosyloxy-3-methoxyphenyl)ethyl]chromone (1), was isolated from the high-quality Chinese agarwood “Qi-Nan” originating from Aquilaria sinensis (Lour.) Glig. The structure including the absolute configuration of the sugar moiety was elucidated by spectroscopic techniques (UV, IR, 1D and 2D NMR), MS analysis, PMP-labeling HPLC analysis methods, as well as comparison with literature data. To the best of our knowledge, it is the first time that chromone glycoside was discovered in agarwood, or even in the whole Aquilaria plants.

Antioxidant phenolic compounds of cassava (Manihot esculenta) from Hainan.

An activity-directed fractionation and purification process was used to isolate antioxidant components from cassava stems produced in Hainan. The ethyl acetate and n-butanol fractions showed greater DPPH˙and ABTS·+ scavenging activities than other fractions. The ethyl acetate fraction was subjected to column chromatography, to yield ten phenolic compounds: Coniferaldehyde (1), isovanillin (2), 6-deoxyjacareubin (3), scopoletin (4), syringaldehyde (5), pinoresinol (6), p-coumaric acid (7), ficusol (8), balanophonin (9) and ethamivan (10), which possess significant antioxidant activities. The relative order of DPPH· scavenging capacity for these compounds was ascorbic acid (reference) > 6 > 1 > 8 > 10 > 9 > 3 > 4 > 7 > 5 > 2, and that of ABTS·+ scavenging capacity was 5 > 7 > 1 > 10 > 4 > 6 > 8 > 2 > Trolox (reference compound) > 3 > 9. The results showed that these phenolic compounds contributed to the antioxidant activity of cassava.