Coumarins from Amyris balsamifera

Two new coumarins have been isolated from the aerial parts of Amyris balsamifera. On the basis of spectral and chemical data, these have been identified as (R)-(+)-6-(2′-hydroxy-3′-methyl-3′-butenyl)-7-methoxycoumarin and balsamiferone, 7-hydroxy-3,6-bis (3′-methyl-2′-butenyl)-coumarin.     

小叶臭黄皮的黄酮苷甙成分

从云南西双版纳的小叶臭黄皮（Clausena excavata Burm.f.）中分离到一个新黄酮甙,5,7,5′－三羟基－3′,4′－二甲氧基黄酮3－0－α－L－吡喃鼠李糖甙（1）和4个已知黄酮甙,分别为5,7,3′,5′－四羟基－4′－甲氧基黄酮3－O－α－L－吡喃鼠李糖甙（2）,5,7,3′－三羟基－4′－甲氧基黄酮3－O－α－L－吡喃鼠李糖甙（3）,5,7,4′－三羟基－3′,5′－二甲氧基黄酮3－O－α－L－吡喃鼠李糖甙（4）,5,7,4′－三羟基黄桐3－O－α－L－吡喃鼠李糖甙（5）。根据HMQC、HMBC实验修正了化合物2－5C6和C8的位碳化学位移的归属。     

Coumarins from unripe fruits of Poncirus trifoliata

Petrol extracts of unripe fruits of Poncirus trifoliata L. were found to contain 7-geranyloxycoumarin, bergapten, imperatorin, 6-methoxy-7-geranyloxycoumarin and two new coumarins which were shown by chemical and spectroscopic means to be 7-(3′-methyl-2′,3′-epoxybutyloxy)-8-(3″-methyl-2″,3″-epoxybutyl)coumarin and 7-(3′-methyl-2′,3′-epoxybutyloxy)-8-(3″-methyl-2″-oxobutyl)coumarin respectively.     

Wampetin,a furocoumarin from Clausena wampi

A new furocoumarin wampetin has been isolated from Clausena wampi (syn. Clausena lansium). The structure was established from ¹H NMR, ¹³C NMR, MS and chemical data.     

Binding of 5-methoxypsoralen to human serum low density lipoproteins

5-methoxypsoralen (5-MOP) binds to human serum low density lipoproteins (LDL) according to a two-step process. Scatchard analysis of the first step yields K = 1.4 × 10⁵ M^?1 and 4 binding sites. It involves the LDL apoprotein. The second step corresponds to a solubilization, in the lipidic core, of ? 45 molecules of 5MOP per LDL molecule. It is accompanied by a large blue shift of the 5MOP fluorescence. The ability of LDL to bind 5MOP and to carry it into various cells may explain some biological effects sometimes encountered during PUVA therapy.     

Coumarins from Triphasia trifoliata

A methanolic extract of the leaves of Triphasia trifoliata contained isomeranzin, umbelliferone and 7-(3′-methyl-2′,3′-dihydroxybutyloxy)-8-(3″-methyl-2″-oxobutyl) coumarin (triphasiol).     

Bioactive Coumarins from the Stems of Clausena emarginata

Five new coumarins, clauemarmarins I – M ( 1 – 4 ), together with 10 known analogs ( 5 – 14 ), were isolated from the stems of Clausena emarginata. Compounds 8 – 13 were obtained from this plant for the first time. Their structures were established and elucidated by comprehensive analysis of spectroscopic data. The absolute configurations of 1 – 4 were further determined by their electronic circular dichroism spectroscopy. Compounds 5 , 7 , 12 , and 14 exhibited inhibitory effects on LPS‐induced NO production. Compounds 5 – 7 showed selective neuroprotective effects in Aβ_{25 – 35} model at 10 μm .     

Carbazole alkaloids with antiangiogenic activities from Clausena sanki

Two new carbazole alkaloids 1 and 2, and eleven known congeners 3–13 were isolated and identified from Clausena sanki for the first time. Their structures were elucidated on the basis of extensive UV, IR, MS, NMR spectroscopic data and comparison with literatures. The compounds 1–13 were evaluated by MTT assay to determine whether they decreased VEGF-mediated cell proliferation in HUVECs with Axitinib as positive control. Among them, compounds 1, 2, 6, 8, and 13 (μM) exhibited moderate antiangiogenic activities, which inhibited VEGF-induced HUVEC proliferation in vitro with IC₅₀ values of 12.1 (C.I. 8.2–15.2), 58.1 (C.I. 56.3–63.4), 13.7 (C.I. 9.2–15.4), 16.0 (C.I. 9.5–16.4), and 63.2 (C.I. 57.8–65.7) μM, respectively. Moreover, the antiangiogenic activities of compounds 1–13 were evidenced in vivo in the zebrafish embryo model. As a result, compounds 1, 2, 6, 8, and 13 showed effectively suppress angiogenesis. These research results may guide the search for new natural products with antiangiogenic attributes.     

Coumarins from Brosimum rubescens

The heartwood of Brosimum rubescens Taubert contains the 7-hydroxycoumarins 7-demethyl-suberosin (IIa) and xanthyletin (Ia) besides the 7,8-dihydroxycoumarins brosiparin (IIb), brosiprenin (IVa) and luvangetin (Ic).     

Coumarins and psoralens in grapefruit peel oil

Four coumarins, four psoralens and two methoxyflavones were isolated and identified from the peel oil of grapefruit. Five of these compounds are reported as constituents of grapefruit oil for the first time, one of which, 5[(3,7-dimethyl-6-epoxy-2-octenyl) oxy]psoralen is a new natural product.     

4′-hydroxy-3,5,6,7,3′,5′-hexamethoxyflavone from Murraya paniculata

4′-Hydroxy-3,5,6,7,3′,5′-hexamethoxyflavone has been isolated from the leaves of Sri Lankan Murraya paniculata.     

Heptazolicine,a carbazole alkaloid from Clausena heptaphylla

A new carbazole alkaloid designated as heptazolicine has been isolated from the roots of Clausena heptaphylla. On the basis of spectral and chemical evidence it has been identified as [2,2-dimethyl-3,4-dihydropyrano-(5, 6-a)]-3-formyl-8-hydroxy-carbazole.