ConspectusActivation of unsaturated carbon–carbon bonds by means of transition metal catalysts is an exceptionally active research field in organic synthesis In this context, due to their high ring strain, cyclopropenes constitute an interesting class of substrates that displays a versatile reactivity in the presence of transition metal catalysts Metal complexes of vinyl carbenes are involved as key intermediates in a wide variety of transition metal-catalyzed ring-opening reactions of cyclopropenes Most of the reported transformations rely on intermolecular or intramolecular addition of nucleophiles to these latter reactive species This Account focuses specifically on the reactivity of carbenoids resulting from the ring-opening of cyclopropenes in cyclopropanation and C–H insertion reactions, which are arguably two of the most representative transformations of metal complexes of carbenesCompared with the more conventional α-diazo carbonyl compounds, the use of cyclopropenes as precursors of metal ca

Intramolecular cyclopropanation and C-H insertion reactions with metal carbenoids generated from cyclopropenes.

Soil microorganisms with growth-promoting activities in plants, including rhizobacteria and rhizofungi, can improve plant health in a variety of different ways. These beneficial microbes may confer broad-spectrum resistance to insect herbivores. Here, we provide evidence that beneficial microbes modulate plant defenses against insect herbivores. Beneficial soil microorganisms can regulate hormone signaling including the jasmonic acid, ethylene and salicylic acid pathways, thereby leading to gene expression, biosynthesis of secondary metabolites, plant defensive proteins and different enzymes and volatile compounds, that may induce defenses against leaf-chewing as well as phloem-feeding insects. In this review, we discuss how beneficial microbes trigger induced systemic resistance against insects by promoting plant growth and highlight changes in plant molecular mechanisms and biochemical profiles.

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Induction of Systemic Resistance against Insect Herbivores in Plants by Beneficial Soil Microbes.

Synthesis and biological evaluation of allylated and prenylated mono-carbonyl analogs of curcumin as anti-inflammatory agents.

Advanced research on acteoside for chemistry and bioactivities

Lignans, which are widely distributed in higher plants, represent a vast and rather diverse group of phenylpropane derivatives. They have attracted considerable attention due to their pharmacological activities. Some of the lignans have been developed approved therapeutics, and others are considered as lead structures for new drugs. This article is based on our previous review of lignans discovered in the period 2000-2004, and it provides a comprehensive compilation of the 354 new naturally occurring lignans obtained from 61 plant families between 2005 and 2011. We classified five main types according to their structural features, and provided the details of their sources, some typical structures, and diverse biological activities. A tabular compilation of the novel lignans by species is presented at the end. A total of 144 references were considered for this review.

New lignans and their biological activities.

Three new compounds, magnolianone (1), erythro-honokitriol (2), and threo-honokitriol (3), together with 14 known compounds, magnaldehyde (4), magnatriol B (5), randaiol (6), obovatol (7), magnolignan B (8a and 8b), magnolol, honokiol (9), p-hydroxylbenzaldehyde, coniferaldehyde, coniferol alcohol, syringaldehyde, syringaresinol, and acteoside, were isolated from the MeOH-soluble part of a water extract of the stem bark of Magnolia officinalis. Among these compounds, 2-8b were studied for anti-inflammatory and antioxidative activities. Compound 7 displayed more potent antioxidative potential than 9. Compounds 4-7 effectively inhibited LPS-induced NO production, whereas 5 and 6 were more potent than 9.

Phenolic Constituents from the Stem Bark of Magnolia officinalis

Four new apigenin derivatives, 7-de-O-methylaciculatin, 8-C-β-D-boivinopyranosylapigenin, aciculatinone, and 4'-O-glucosylaciculatin, along with eight known compounds, apigenin-8-carbaldehyde, kaempferol, tricin, taxifolin, 6,7,4'-trihydroxyflavone, trans-oxyresveratrol, aciculatin, and luteolin-7-sulfate, were isolated from an ethanolic extract of Chrysopogon aciculatis. Their chemical structures were elucidated by spectroscopic methods. Among the known compounds, the natural occurrence of apigenin-8-carbaldehyde and luteolin-7-sulfate is demonstrated for the first time. Some of the isolates were evaluated for cytotoxic activity against human cancer cell lines including MCF-7, H460, HT-29, and CEM.

Ching Li Ni

Papers

Phenolic Constituents from the Stem Bark of Magnolia officinalis

Cytotoxic apigenin derivatives from Chrysopogon aciculatis