Isolation and structural studies on the chemical constituents of skimmialaureola

Construction of 4-Acyl-2-quinolones through Sc(OTf)3-Catalyzed Ring-Closing Alkyne-Carbonyl Metathesis

An atom-economical protocol to construct densely substituted 4-acyl-2-quinolones from N-(2-alkynylphenyl)-α-ketoamides has been developed through Sc(OTf)₃-catalyzed ring-closing alkyne-carbonyl metathesis. Mechanistic experimental studies support that coordinative interaction between Sc(OTf))₃ and the substrate, the formation of an oxetene intermediate, and an electrocyclic ring-opening of the oxetene might be involved.

New Anti-inflammatory Triterpene Esters and Glycosides from Alstonia scholaris

BACKGROUND

Phytochemical studies on the ethanolic extract of aerial parts of Alstonia scholaris lead to the isolation of two new triterpenoid of the lanostanetype, lanosta 5ene,24-ethyl-3-O-β-D-glucopyranoside (1), lanosta,5ene,24-ethyl-3-O-β-D-glucopyranosideester (2) and new ursane type triterpenoidmethylester, 12-ursene-2,3,18,19-tetrol,28 acetate (nighascholarene) (3), together with seven known triterpenes, betuline, triterpene of the lupane type, alstoprenyol (4), 3β-hydroxy-28-β-acetoxy-5-olea triterpene (5),α-amyrin acetate (6), α-amyrin (7), lupeol acetate (8), 3β-hydroxy-24-nor-urs-4,12,28-triene triterpene (9) and ursolic acid (l0).

METHODOLOGY

The triterpenoid structures of these colorless compounds were deduced from the 1H and 13C-NMR data, and in particular from the application of two-dimensional 1H, 13C correlation experiments as well as by comparison with reported literature data.

CONCLUSION

This study deals with isolation and structural elucidation of natural new triterpenoidesters and glycosides with anti-inflammatory activity.

Phytochemistry of the genus Skimmia (Rutaceae)

The genus Skimmia is a rich source of interesting secondary metabolites, including 20 alkaloids derived from anthranilic acid, 45 coumarins, 21 limonoids, four cholestane derivatives, six pentacyclic triterpenes, six flavonoids, and two unusual fatty acid derivatives. Skimmia is employed in folk medicine e.g. against fever, inflammations, and rheumatism. Skimmia extracts, Skimmia essential oils and pure compounds isolated from Skimmia extracts have been experimentally shown to have various bioactivities such as antioxidant, anti-inflammatory, antimicrobial, and insecticidal. In this review we discuss the exact structures of compounds isolated from members of the genus Skimmia, bioactivities of Skimmia extracts and pure compounds derived from them, and systematic implications of the patterns of occurrence of these compounds. Moreover, research gaps and interesting avenues for future research are discussed briefly.

Chemical composition and antimicrobial activity of the leaf essential oil of Skimmia laureola growing wild in Jammu and Kashmir, India

The analysis of Skimmia laureola hydrodistillate by gas chromatography coupled with mass spectrometry revealed the presence of 20 constituents, representing 94.6% of the total oil. The major constituents of oil were linalyl acetate (33.0%), linalool (25.0%), limonene (8.1%), α-terpineol (5.9%) and geranyl acetate (5.9%). The monoterpene (93.4%) rich essential oil was evaluated for its antibacterial and antifungal activities against seven microorganisms by agar diffusion and microdilution methods. The oil showed appreciable antimicrobial effects against all Gram-positive bacteria tested, including methicillin-resistant Staphylococcus aureus and Staphylococcus epidermidis with MIC values 32 and 64 µg mL(-1), respectively. The oil also exhibited strong fungicidal activity against Aspergillus niger and Penicillium chrysogenum with MIC value in the range 32-16 µg mL(-1). The oil could be used in the formulation of antimicrobial agents.

Tyrosinase-inhibitory long-chain esters from Amberboa ramosa

Long-chain esters 1 and 2 have been isolated from the chloroform-soluble fraction of Amberboa ramosa and their structures assigned to be methyl 2beta(2S)-hydroxyl-7(E)-tritriacontenoate (1) and methyl 2beta(2S)-O-beta-D-galactopyranosyl-7(E)-tetratriacontenoate (2). In addition, tricontane (3) and apigenin (4) are also reported for the first time from this species. The structures were assigned on the basis of 1D and 2D NMR techniques. Compounds 1 and 2 showed strong to moderate inhibitory activity against tyrosinase.

Synthesis of Unnatural 1-Methyl-2-quinolone Derivatives

Unnatural 1-methyl-2-quinolone derivatives were synthesized by regioselective C-C bond formation. When 1-methyl-3,6,8-trinitro-2-quinolone (TNQ) was treated with enamines, nucleophilic addition readily occurred at the 4-position, and succeeding hydrolysis of enamine moiety followed by elimination of nitrous acid furnished 4-acylmethyl-1-methyl-6,8-dinitro-2-quinolones. The same products could be prepared by the reaction of TNQ with ketones in the presence of triethylamine. The present reaction enabled the introduction of various kinds of acylmethyl groups substituted with alkyl, aryl or hetaryl groups.