The cyclopentenone unit is a very powerful synthon for the synthesis of a variety of bioactive target molecules. This is due to the broad diversity of chemical modifications available for the enone structural motif. In particular, chiral cyclopentenones are important precursors in the asymmetric synthesis of target chiral molecules. This Review provides an overview of reported methods for enantioselective and asymmetric syntheses of cyclopentenones, including chemical and enzymatic resolution, asymmetric synthesis via Pauson-Khand reaction, Nazarov cyclization and organocatalyzed reactions, asymmetric functionalization of the existing cyclopentenone unit, and functionalization of chiral building blocks.

Synthesis of Chiral Cyclopentenones.

This article provides morphological descriptions and illustrations of microfungi associated with the invasive weed, Chromolaena odorata, which were mainly collected in northern Thailand. Seventy-seven taxa distributed in ten orders, 23 families (of which Neomassarinaceae is new), 12 new genera (Chromolaenicola, Chromolaenomyces, Longiappendispora, Pseudocapulatispora, Murichromolaenicola, Neoophiobolus, Paraleptospora, Pseudoroussoella, Pseudostaurosphaeria, Pseudothyridariella, Setoarthopyrenia, Xenoroussoella), 47 new species (Aplosporella chromolaenae, Arthrinium chromolaenae, Chromolaenicola chiangraiensis, C. lampangensis, C. nanensis, C. thailandensis, Chromolaenomyces appendiculatus, Diaporthe chromolaenae, Didymella chromolaenae, Dyfrolomyces chromolaenae, Leptospora chromolaenae, L. phraeana, Longiappendispora chromolaenae, Memnoniella chromolaenae, Montagnula chiangraiensis, M. chromolaenae, M. chromolaenicola, M. thailandica, Murichromolaenicola chiangraiensis, M. chromolaenae, Muyocopron chromolaenae, M. chromolaenicola, Neomassarina chromolaenae, Neoophiobolus chromolaenae, Neopyrenochaeta chiangraiensis, N. chromolaenae, N. thailandica, N. triseptatispora, Nigrograna chromolaenae, Nothophoma chromolaenae, Paraleptospora chromolaenae, P. chromolaenicola, Patellaria chromolaenae, Pseudocapulatispora longiappendiculata, Pseudoroussoella chromolaenae, Pseudostaurosphaeria chromolaenae, P. chromolaenicola, Pseudothyridariella chromolaenae, Pyrenochaetopsis chromolaenae, Rhytidhysteron chromolaenae, Setoarthopyrenia chromolaenae, Sphaeropsis chromolaenicola, Tremateia chiangraiensis, T. chromolaenae, T. thailandensis, Xenoroussoella triseptata, Yunnanensis chromolaenae), 12 new host records, three new taxonomic combinations (Chromolaenicola siamensis, Pseudoroussoella elaeicola, Pseudothyridariella mahakashae), and two reference specimens (Torula chromolaenae, T. fici) are described and illustrated. Unlike some other hosts, e.g. bamboo (Poaceae) and Pandanaceae, the dominant group of fungi on Siam weed were Dothideomycetes. Only 15 species previously recorded from northern Thailand were found in this study. Most of the taxa are likely to have jumped hosts from surrounding plants and are unlikely to be a specialist to Siam weed. Most fungal families found on Siam weed had divergence estimates with stem ages in the Cretaceous, which coincided with the expected origin of the host family (Asteraceae). This further indicates that the species have jumped hosts, as it is unlikely that the taxa on the alien Siam weed came from the Americas with its host. They may, however, have jumped from other Asteraceae hosts. In a preliminary screening 40 (65%) of the 62 species tested showed antimicrobial activity and thus, the fungi associated with C. odorata may be promising sources of novel bioactive compound discovery. We provide a checklist of fungi associated with C. odorata based on the USDA Systematic Mycology and Microbiology Laboratory (SMML) database, relevant literature and our study. In total, 130 taxa (116 identified and 14 unidentified species) are distributed in 20 orders, 48 families, and 85 genera. Pseudocercospora is the most commonly encountered genus on Siam weed.

Taxonomic and phylogenetic contributions to fungi associated with the invasive weed Chromolaena odorata (Siam weed)

The health challenges associated with pathogens and ectoparasites highlight the need for effective control approaches. Metal nanoparticles have been proposed as highly effective tools towards combatting different microbial organisms and parasites. The present work reports the antimicrobial and larvicidal potential of biosynthesized Ag/Ag2O nanoparticles using aqueous leaf extract of Eupatorium odoratum (EO). The constituents of the leaf extract act as both reducing and stabilizing agents. The UV-VIS spectra of the nanoparticles showed surface plasmon resonance. The particle size and shape of the nanoparticles was analysed by transmission electron microscopy (TEM). The larvicidal study was carried out using third and fourth instar Culex quinquefasciatus larvae. The mosquito larvae were exposed to varying concentrations of plant extract (EO) and the synthesized nanoparticles, and their percentage of mortality was accounted for at different time intervals of 12 h and 24 h periods of exposure. The nanoparticles were more lethal against third and fourth instars of Culex quinquefasciatus larvae at the 24 h period of exposure with lower lethal concentration values (LC50 = 95.9 ppm; LC90 = 337.5 ppm) and (LC50 = 166.4 ppm; LC90 = 438.7 ppm) compared to the plant extract (LC50 = 396.8 ppm; LC90 = 716.8 ppm and LC50 = 448.3 ppm; LC90 = 803.9 ppm, respectively). The antimicrobial properties of the nanoparticles were established against different clinically-isolated microbial strains and compared to that of the plant extract (EO) and standard antimicrobial drugs. The nanoparticles were generally more active than the plant extract against the selected microbial organisms. The Gram-negative bacterial strains Escheerichua coli and Salmonella typhi were more susceptible towards the nanoparticles compared to the Gram-positive strains and the fungal organism.

https://www.mdpi.com/1420-3049/22/5/674/pdf

Green Synthesis of Ag/Ag₂O Nanoparticles Using Aqueous Leaf Extract of Eupatorium odoratum and Its Antimicrobial and Mosquito Larvicidal Activities.

The essential oil from the dried leaves of Chromolaena odorata (L.) R.M. King & H. Rob. was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS). The major components were �-pinene (42.2%), �-pinene (10.6%), germacrene D (9.7%), �-copaen-4�-ol (9.4%), ( E)- caryophyllene (5.4%), and geijerene/pregeijerene (7.5%). The oil was screened for antimicrobial activity and showed antibacterial activity against Bacillus cereus (MIC = 39 µg/mL) and antifungal activity against Aspergillus niger (MIC = 78 µg/mL). DFT (B3LYP/6-31G*) and post-HF (MP2/6-311+G**) indicate that pregeijerene is less stable (0.45 and 3.99 kcal/mol, respectively) than its Cope rearrangement product geijerene.

/pdf/chemical-composition-and-bioactivity-of-the-essential-oil-of-59ilm3pr2v.pdf

Chemical Composition and Bioactivity of the Essential Oil of Chromolaena odorata from Nigeria

Anti-inflammatory effects of fatty acids isolated from Chromolaena odorata

Constituents of the essential oil from aerial parts of Chromolaena odorata from Thailand

A chemo-enzymatic synthesis of (−)-epipentenomycin I is reported using a lipase-catalysed kinetic resolution of the racemic pentacyclic alcohol 8 . Flash vacuum pyroloysis of (−)- 8 so obtained gave (−)-(4 R )-4-hydroxy-5-methylene-2-cyclopentenone. Epoxidation of this compound with dimethyldioxirane followed by hydrolytic ring-opening of the resulting epoxide gave (−)-epipentenomycin I.

/pdf/chemo-enzymatic-synthesis-of-epipentenomycin-i-1wgx84sqda.pdf

Chemo-enzymatic synthesis of (−)-epipentenomycin I

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=8665&context=scipapers

Synthesis of (±) epipentenomycin I and III

A synthesis of (±) epipentenomycin I and III is reported from a regioselective epoxidation of racemic 3-hydroxy- and 3-acetoxy-2-methylene-4-cyclopentenone, respectively, with dimethyldioxirane followed by hydrolytic ring-opening of the resulting epoxide.

Apiwat Baramee

Papers

Constituents of the essential oil from aerial parts of Chromolaena odorata from Thailand

Chemo-enzymatic synthesis of (−)-epipentenomycin I

Synthesis of (±) epipentenomycin I and III

Synthesis of (.+-.) Epipentenomycin I and III.