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C20H22N2O8, monoclinic, P21/c (no. 14), a = 8.7634(8) Å, b = 17.9290(18) Å, c = 12.8437(9) Å, β = 100.013(8)°, V = 1987.3(3) Å3, Z = 4, R gt(F) = 0.0401, wR ref(F 2) = 0.1026, T = 170 K.

C17H14N2O3S, monoclinic, P21/c (no. 14), a = 9.8966(5) Å, b = 9.4360(4) Å, c = 16.7115(7) Å, β = 92.245(4)°, V = 1559.39(12) Å3, Z = 4, R gt(F) = 0.0358, wR ref(F 2) = 0.1013, T = 170 K.

Introduction Minor plant constituents are difficult to identify due to the challenging isolation and acquiring of reliable spectral data. Essential oils abound in such minor constituents that might be of high importance for their (e.g. olfactory) properties. The presence of new minor constituents is usually inferred from gas chromatography mass spectrometry (GC-MS) analyses that provide only a mass spectrum and retention data, which are insufficient to allow a positive identification. Objective To identify a minor unknown constituent of the essential oil of Achillea abrotanoides (Vis.) Vis. (Asteraceae). Methodology The application of chemical transformations (oxidation and reduction) performed directly on crude essential-oil samples, followed by preparative chromatography and detailed spectral analysis, to identify a new longipinane ketone from the mentioned sample. Results GC-MS analyses of the essential oil revealed, among other constituents, the presence of a known rare longipinane alcohol (α-longipinen-7β-ol) representing 2.5% of the total GC-peak areas, and a related unidentified oxygenated sesquiterpene (3.8%). Interpretation of their mass spectra led to an assumption that the unidentified one could represent α-longipinen-7-one. Oxidation of the entire essential-oil sample by pyridinium chlorochromate confirmed the assumed relationship among the compounds and gave a simplified enriched mixture containing the ketone (ca. 16%). A straightforward chromatographic separation of the ketone was followed by corroboration of its structure by nuclear magnetic resonance (NMR) (one- and two-dimensional), infrared (IR) and MS. Conclusions The complementing use of chemical transformations of crude essential oils, chromatographic separations, and detailed spectral analysis could have a more general application in the identification of new natural products.

Considering the facts that phenolic compounds have many pharmacological effects, as well that antioxidant effect of phenolic compounds has been proven in various experimental systems, aim of this research was to determine the content of total phenols and flavonoids and evaluation of antioxidant activity in ethanol, ethyl acetate and chloroform extracts of fruits and leaves of the plant species Crataegus monogya Jacq., which is known as common hawthorn. The content of total phenolic compounds was determined by the spectrophotometric method using Folin-Ciocalteu reagent and the content of flavonoids was determined using aluminum chloride. In vitro evaluation of the antioxidant activity of tested extracts was performed using the DPPH method. The amount of total phenolics was varied in fruits and leaves extracts and ranged from 38.05 ± 0.18 to 365.11 ± 0.32 mg GAE/g dw. Ethyl acetate extract of hawthorn leaves showed the highest content of phenolic compounds (365.11 ± 0.32 mg GAE/g dw). The flavonoid content was different in the fruits and leaves of hawthorn and ranged from 21.11 ± 0.11 to 122.98 ± 0.21 mg RU/g dw, whereby the highest content of flavonoids was found in ethyl acetate extract of leaves (122.98 ± 0.21 mg RU/g dw). Antioxidant activity of the tested extracts was expressed as IC50 values and ranged from 5.53 ± 0.08 to 293.51 ± 0.28 mg/ml. Ethyl acetate extract of hawthorn leaves showed considerable antioxidant potential (IC50 = 5.53 ± 0.08 mg/ml). Based on the obtained results, a significant correlation was found between the antioxidant activity and the content of total phenolics and flavonoids compounds in hawthorn fruits and leaves extracts.

This research involves the reaction of 4-chloro-3-nitrocoumarin and (4-methoxyphenyl)methanamine, whereby a novel coumarin derivative 4-[(4-methoxybenzyl) amino]-3-nitro-2H-chromen-2-one was obtained in good yield. The reaction was carried out in ethyl acetate, in the presence of triethylamine. Also, a detailed spectral analysis of a new coumarin derivative is presented. Resonance assignment was achieved using one- (1H NMR and 13C NMR) and two-dimensional NMR techniques (1H-1H-COSY, NOESY, HSQC, and HMBC). The NOESY correlations of protons from arylamino substituent and coumarin core indicate their spatial orientation.

C16H12N2O4, triclinic, P1̄ (no. 2), a = 10.7105(5) Å, b = 11.2685(5) Å, c = 13.0145(6) Å, α = 99.292(4)°, β = 109.607(4)°, γ = 96.771(4)°, V = 1435.01(12) Å3, Z = 4, Rgt(F) = 0.0427, wRref(F2) = 0.1124, T = 295(2) K.

C22H18O10Zn, triclinic, P1̄ (no. 2), a = 7.9616(3) Å, b = 9.5386(3) Å, c = 14.2569(4) Å, α = 81.713(3)°, β = 82.724(3)°, γ = 73.103(3)°, V = 1021.03(6) Å3, Z = 2, R gt(F) = 0.0223, wR ref(F 2) = 0.0603, T = 295(2) K.

Some carnation species (Dianthus spp., Caryophyllaceae) exhibit a strong resistance to drought stress that is connected with the increased surface wax formation. Wax composition is unknown for the majority of Dianthus spp. Herein, mass spectral and gas chromatographic data, in combination with synthesis and chemical transformations (transesterification and synthesis of dimethyl disulfide adducts), enabled the identification of 151 constituents of diethyl-ether washings of fresh flowers of Dianthus cruentus Griseb. from Serbia. The flower wax contained, along with the dominant ubiquitous long-chain n-alkanes, homologous series of n- and branched (iso- and anteiso-) long-chain hexyl alkanoates/alkenoates and alkyl/alkenyl benzoates. The branching position in the mentioned hexyl esters was probed by synthesis of esters of three isomeric hexanols that were spectrally characterized (1 H- and 13 C-NMR, IR, MS). The washings also contained long-chain (Z)- and (E)-alkenes (C23 -C35 ) with several different double bond regiochemistries. Fifty-five of these constituents (eight hexyl esters, two benzoates, and forty-five alkenes) were detected for the first time in Plantae, while ten of these represent completely new compounds. The rare occurrence of these wax constituents makes them possible chemotaxonomic markers of this particular Dianthus sp.

Complete assignment of the 1 H and 13 C NMR chemical shifts of new coumarin derivate was described in this paper. A new coumarin derivate was synthesized in good yield by reaction of 4-chloro-3-nitrocoumarin and 6-nitrobenzothiazol-2-amine in ethyl acetate in the presence of triethylamine. The complete spectral assignment was achieved using of 1D ( 1 H and 13 C NMR) and 2D ( 1 H- 1 H-COSY, NOESY, HSQC and HMBC) NMR experiments.

Nine unsymmetrical azines containing a coumarin moiety were prepared by the reaction of the hydrazone of 4-hydroxy-3-acetylcoumarin with differently substituted aromatic aldehydes. The azines were fully spectrally characterized, including a complete assignment of 1 H- and 13 C-NMR resonances, and were assessed for their acute toxicities in the Artemia salina model. Their free radical scavenging activities were tested in the DPPH assay, and in vitro antimicrobial activities were determined against seven bacterial and two fungal strains. The azines containing a p-hydroxyphenyl group were shown to be the most effective antimicrobial agents, and in the case of resistant strains of Staphylococcus aureus and Acinetobacter baumannii, the activity was comparable to that of chloramphenicol. The derivative having a 3,5-dimethoxy-4-hydroxyphenyl group exhibited pronounced antioxidant power reacting rapidly and in 1 : 1 mol ratio with the DPPH radical.

Synthesis, spectral characterization, and evaluation of in vitro antioxidant activity of a new coumarin derivative, 4- ((1,3,4-thiadiazol-2-yl)amino)-3-nitro-2H-chromene-2-one, are described. The synthesis of the new product was performed in three reaction steps, with a good overall yield (78%). The structure was corroborated by detailed spectral analysis, including the 1D and 2D NMR experiments (1H- and 13C NMR; 1H-1H COSY, NOESY, HSQC, and HMBC). The in vitro antioxidant activity was evaluated using the DPPH test. The synthesized compound possesses a good free-radical scavenging activity, IC50=596.7±0.3 μg/ml, and can serve as a model for the synthesis of similar compounds with promising antioxidant effects.