Search results for "lactone"

First transformations of pyrano[3,4-b]indol-3-ones to salvadoricine and 2,3-diacylindoles

1992

The readily available methylated pyrano[3,4-b]indol-3-ones 1a and 1b were hydrolyzed to furnish the 2-acetylindol-3-alkanoic acids 2 and 4. Compound 2 was easily transformed selectively to 2-acetyl-3-methylindole (3, salvadoricine). Substrate 1b reacts with molecular oxygen from the air only in the presence of a catalyst to give 2,3-diacetylindole (5) while 1a reacts with nitrosobenzene via a proposed Diels-Alder step to yield 2-acetylindole-3-carbaldehyde (6). The latter product can also be obtained in low yield from the reaction of 1a with molecular oxygen from the air.

Non-hindered ansasamarocenes, versatile catalysts for diene/olefin/polar monomer copolymerisations. What is really the active species?

2002

Abstract Catalytic systems containing an ansabiscyclopentadienyllanthanide core and lithium and/or magnesium salts are obtained by reaction of the chloride precursors with allyllithium. These allyl complexes lead to the same active species which polymerises 1,3-dienes, copolymerises 1,3-dienes and α-olefin or α,ω-dienes or allows the controlled diblock polyisoprene/polycaprolactone copolymerisation. The exact nature of this active species and of the allyl precursors is investigated here.

Effect of Streptomyces coelicolor M145 cell immobilization on actinorhodin production

2016

Non previsto

Modification of EVOH copolymers with e-caprolactone: synthesis and compatibilization effects in PE/PVC blends

2001

Polyethylene-polycaprolactone graft copolymers with different chemical structures (i.e. different number and length of PCL grafts and molecular weight of PE backbone) were synthesized from various EVOH copolymers and e-caprolactone, using Aluminum isopropoxide as catalyst, and were tested for their compatibilizing capability in PE/PVC blends. PE and PCL segments in the graft copolymers were found completely immiscible, while PCL segments of the graft copolymers were found completely miscible with PVC. When graft copolymers were added to PE/PVC blends they proved to be good agents for the dispersion of PVC phase in the PE matrix. SEM showed also improved adhesion between the dispersed PVC ph…

Cytotoxic activity of some natural and synthetic guaianolides

2005

Several natural guaianolides and synthetic derivatives of repin (1) were tested and found to be active against tumor cell replication. Repin (1) and both mono- and di-halohydrin analogues (2, 7-9, 11, 12) showed significant antitumor potency. A more effective compound (17) was obtained by esterificating repin with the paclitaxel side chain.

Phytotoxic Lignans from Artemisia arborescens

2018

A systematic bioassay-guided fractionation of methylene chloride extracts of the aerial part of Artemisia arborescens was performed in order to identify its phytotoxic compounds Two lignans were isolated, sesamin and ashantin, that inhibited growth of Agrostis stolonifera (bentgrass), a monocot, and Lactuca sativa (lettuce), a dicot, at 1 mg mL–1. In a dose-response screening of these lignans for growth inhibition against Lemna paucicostata (duckweed), ashantin was the most active with an IC50 of ca. 224 μM. The mode of action of these compounds is still unknown. In mosquito larvicidal bioassays the pure compounds sesamin and ashantin did not cause mortality at the highest dose of 125 mg/L…

In vivo stimulation of murine haematopoiesis by the antineoplastic agent bryostatin-1

1990

In vivo activity of pseudoguaianolide sesquiterpene lactones in acute and chronic inflammation.

2000

The pseudoguaianolide sesquiterpene lactones 4-alpha-O-acetyl-pseudoguaian-6beta-olide (1), hymenin (2), ambrosanolide (3), tetraneurin A (4), parthenin (5), hysterin (6) and confertdiolide (7) were evaluated for their ability to affect the inflammation responses induced by different agents. All the compounds showed activity against the 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced mouse ear edema. The ethyl phenylpropiolate (EPP)-induced mouse ear edema was inhibited by compounds 3, 5 and 7. However, when sesquiterpene-lactones were assayed on the arachidonic acid (AA)-induced mouse ear edema, none of them were active. The only sesquiterpene lactone orally active against the paw mouse…

Neoclerodane Diterpenoids from Scutellaria pontica

1997

Seven novel neoclerodane diterpenoids, scupontins A-G, have been isolated from the Me2CO extract of the aerial parts of Scutellaria pontica (1-7), together with the known neoclerodanes scutalbin A and scutalpin M. Structures 1-7 were established by exhaustive NMR spectroscopic studies and chemical transformations. Scupontins A-D(1-4, respectively) and scupontins E (5)andF(6) possess unusual [(3¢S,3¢¢S)-3¢-[(3¢¢-acetoxybutyryl)oxy]butyryloxy and [(3¢S,3¢¢S,3¢¢¢S)- 3¢-[[3¢¢-[(3¢¢¢-hydroxybutyryl)oxy]butyryl]oxy]butyryl]oxy substituents, respectively, attached to the C-19 position of the neoclerodane framework. In the case of the 6R,7â-dibenzoate derivative 7 (scupontin G) its absolute config…

Neoclerodane Diterpenoids from Teucrium maghrebinum

2000

Eight neoclerodane diterpenoids were identified in the extract of the aerial parts of Teucrium maghrebinum. Three of these, 12-epi-teucjaponin A (1), 12-epi-montanin D (2), and 12-epi-montanin B (3), are new natural products, whereas five, teucjaponin A, montanin D, 19-deacetylteuscorodol, teusalvin C (4), and montanin B, are already known. These eight compounds form four pairs of epimers at carbon C-12.