No abstract available

No abstract available

[en] Phytochemical investigation of the heartwood of Ochroma lagopus Swartz, led to the isolation of coumarins scopoletin and cleomiscosin A; lignans boehmenan and secoisolariciresinoyl diferulate, besides β-sitosterol, stigmasterol and a mixture of fatty acids and esters. Carbon-13 and proton NMR were used to identify and characterize their molecular structure. Infrared spectra and mass spectra were also utilized. (author)

[en] Mixtures of α-Santonin and various solvents were irradiated by either high or low pressure mercury lamps. The photochemical reactions afforded lumisantonin (11) (76% in acetonitrile), (3 S,3a S,9βS)-3,6,6-trimethyl-3,3a,4,5-tetrahydronafto[1,2-b]furan-2,7(Η6,9βΗ) dione (12) (100% in acetonitrile), 10α-acetoxy-3-oxo-1,7αHΗ,6,11αaΗ-guaia-4-en-6,12-olide (8) (26% in acetic acid), 10α-hydroxy-3-oxo-1,7αaΗ,6,11αΗ-guaia-4-en-6,12-olide (10) (32%) and (E)-3-((3 S,3a S,7αS)-3-methyl-2-oxo-6-(propan-2-ylidene)hexahydrobenzofuran- 7 - (7αΗ)-ylidene)propanoic acid (9) (44%) (in water/ acetic acid 1:1, v/v). Lactone 12 was also prepared by irradiation of lumisantonin in diethyl ether. Lactones 8 and 10 were converted, respectively, into the 10 α-acetoxy-3α-hydroxy-1,7αH,6,11αH-guaia-4-en-6,12-olide (13) (87%) and 3a,10a-dihydroxy-1,7αH,6,11αH-guaia-4-en-6,12-olide (14) (75%) by sodium borohydride reduction. The effects of the compounds on the development of radicle of Sorghum bicolor and Cucumis sativus were evaluated. (author)

[en] The first chemical study of non-volatile constituents from the bark and stem of Melaleuca alternifolia (Myrtaceae) led to the isolation and identification of 3,3'-O-dimethylellagic acid (1) and five pentacyclic triterpenes: 2α,3β,23-trihydroxyolean-12-en-28-oic acid (arjunolic acid, 2), 3β-hydroxylup-20(29)-en-27,28-dioic acid (melaleucic acid, 3), betulinic acid (4), betuline (5), 3β-O-acetylurs-12-en-28-oic acid (6), a mixture of fatty acids and esters, and several hydrocarbons. For 2α,3β,23-trihydroxyolean-12-en-28-oic acid (2) and 3β-O-acetylurs-12-en-28-oic acid (6) a first detailed assignment of ¹H NMR is presented. (author)

[en] Considering the broad spectrum of biological activity of gamma-butyrolactone derivatives, we presented the synthesis of 3,4-dihalo-5-arylidenefuran-2(5H)-ones (17-21) and analogues (24-28) of the natural product nostoclide (7,8). Furanones 17-21 were synthesized from the condensation of aromatic aldehydes with lactones 14 and 15, that were obtained from mucobromic and mucochloric acids. Lactone 15 was converted into the intermediate 23 in 36% overall yield. Compound 23 was then transformed into the nostoclide analogues 24-28. Some of the compounds prepared showed antimicrobial activities against Escherichia coli, Staphylococcus aureus and Bacillus cereus comparable to commercial antibiotics. (author)

[en] Short communication. 2 figs

No abstract available

[en] Graphical abstract: - Highlights: • The redox properties of rubrolide analogues were investigated by cyclic voltammetry. • A computational method to predict the redox potential of rubrolides was developed. • Prediction of E_pc of rubrolides analogues was made by DTF calculations. • Rubrolide E_pc correlates to the ability to inhibit the photosynthetic electron flow. - Abstract: To understand and predict the relationship between the redox potential and the inhibitory effect of rubrolide analogues upon the photosynthetic electron transport chain, their redox properties were studied. The reduction potential was determined experimentally in DMSO by means of cyclic voltammetry, and theoretically by using B3LYP/6-31G(d,p) and MPWB1 K/TZVP computational methods. A good correlation was obtained between the two datasets, MPWB1 K/TZVP being the best methodology (correlation coefficient of 0.965 and standard deviation of 0.034, against 0.932 and 0.047 for B3LYP/6-31G(d,p)). A significant relationship was observed between the redox potential of the rubrolide analogues and their ability to interfere with the Hill reaction: the higher the first reduction potential, the more effective the inhibitor. These results will allow for predicting the behavior of novel analogues as inhibitors of the Hill reaction, and directing the synthetic strategy towards more potent inhibitors targeting the photosynthetic electron transport