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A recent in vivo study in pigs demonstrated the hypotensive properties of essential oil extracted from the blossoming plant Elsholtzia ciliata. This study was designed to examine the effect of E. ciliata essential oil (EO) on smooth muscle contraction. Tension measurements were performed on prostate strips and intact aortic rings isolated from rats. Results showed that EO caused a concentration-dependent reduction in phenylephrine-induced contraction of both the prostate and aorta, with a more pronounced inhibitory effect in the prostate. The IC50 of EO for the prostate was 0.24 ± 0.03 µL/mL (n = 10) and for the aorta was 0.72 ± 0.11 µL/mL (n = 4, p < 0.05 vs. prostate). The chromatographic analysis identified elsholtzia ketone (10.64%) and dehydroelsholtzia ketone (86.23%) as the predominant compounds in the tested EO. Since both compounds feature a furan ring within their molecular structure, other furan ring-containing compounds, 2-acetylfuran (2AF) and 5-methylfurfural (5MFF), were examined. For the first time, our study demonstrated the relaxant effects of 2AF and 5MFF on smooth muscles. Further, results showed that EO, 2AF, and 5MFF altered the responsiveness of prostate smooth muscle cells to phenylephrine. Under control conditions, the EC50 of phenylephrine was 0.18 ± 0.03 µM (n = 5), while in the presence of EO, 2AF, or 5MFF, the EC50 values were 0.81 ± 0.3 µM (n = 5), 0.89 ± 0.11 µM (n = 5), and 0.69 ± 0.23 µM (n = 4), respectively, p < 0.05 vs. control. Analysis of the affinity of EO for α1-adrenergic receptors in the prostate suggested that EO at a certain range of concentrations has a competitive antagonistic effect on α1-adrenergic receptors. In conclusion, EO elicits a relaxant effect on smooth muscles which may be related to the inhibition of α1-adrenoreceptors.

2-acetylfuran is a product of the Maillard reaction and is widely found, especially in heat-processed foods such as grain products, baked goods, and dairy products. Although 2-acetylfuran contributes to flavor, high concentrations may be toxic. Its target organs and dose–response relationships remain poorly characterized. In this study, transgenic zebrafish with fluorescently labeled immune and neural systems were used to assess the effects of 2-acetylfuran on immune and neural development. Wild-type zebrafish were employed to assess the toxicity of 2-acetylfuran on locomotor ability, gastrointestinal development, and liver function. The maximum non-lethal concentration (MNLC) and the 10% lethal concentration (LC10) for zebrafish embryos were 0.844 and 0.889 μL/mL, respectively. Regarding immunotoxicity, at concentrations of 0.281, 0.844, and 0.889 μL/mL, 2-acetylfuran significantly reduced the numbers of neutrophils, T cells, and macrophages. Regarding locomotor and neurotoxicity, motor speed and total locomotor distance were significantly reduced at 0.844 and 0.889 μL/mL. These findings were consistent with neurodevelopmental assessments, in which 0.844 μL/mL 2-acetylfuran resulted in a significant increase in apoptotic cells in the central nervous system and markedly shortened peripheral motor nerve lengths. Regarding gastrointestinal toxicity, 0.844 and 0.889 μL/mL 2-acetylfuran significantly reduced the gastrointestinal area, while neutrophil counts showed no significant changes, suggesting a relatively mild effect on the gastrointestinal tract. Regarding hepatic toxicity, all tested concentrations of 2-acetylfuran primarily increased the delayed yolk sac absorption area. Furthermore, at 0.844 μL/mL, histological examination revealed hepatic pathological changes characterized by hepatocyte nuclear swelling, vacuolar degeneration, and hepatocyte necrosis. In summary, this study reveals the multi-organ toxicity profile of 2-acetylfuran in the zebrafish model, with particularly high sensitivity in the immune system and liver. This research provides theoretical support for risk assessment and process control of 2-acetylfuran in foods.

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of 2‐acetylfuran [13.054] and 2‐pentylfuran [13.059] belonging to chemical group 14 (furfuryl and furan derivatives with and without additional side‐chain substituents and heteroatoms), when used as sensory additives (flavourings) in feed for all animal species. 2‐Acetylfuran [13.054] was tested in tolerance studies in chickens for fattening, weaned piglets and cattle for fattening. No adverse effects were observed in the tolerance studies at 10‐fold the intended use level. The FEEDAP Panel concluded that 2‐acetylfuran [13.054] is safe for these species at the proposed use level of 0.5 mg/kg and conclusions were extrapolated to all animal species. For 2‐pentylfuran [13.059], the Panel concluded that it is safe at the proposed maximum use level in feed of 0.5 mg/kg. No safety concern would arise for the consumer from the use of 2‐acetylfuran [13.054] and 2‐pentylfuran [13.059] up to the proposed maximum use level in feed as flavourings. The additives should be considered as irritant to skin and eyes and the respiratory tract, and as dermal and respiratory sensitisers. The use of 2‐acetylfuran [13.054] and 2‐pentylfuran [13.059] as flavours in animal feed was not expected to pose a risk for the environment. Since the compounds under assessment are used in food as flavourings and their function in feed is essentially the same as that in food, no further demonstration of efficacy was considered necessary.

Bromination of 2-acetylfuran with copper(II) bromide in a mixture of ethyl acetate and chloroform leads selectively to furacyl bromide, the nucleophilic substitution of bromine in which by OAc and subsequent use of the Weidenhagen reaction enabled the synthesis of 4(5)-(2-furyl)imidazole. On N-methylation of this imidazole in KOH–acetone 2 isomers are formed, the 1-methyl-4- and 1-methyl-5-(2-furyl)imidazoles. It was established that, unlike alkylation of 4(5)-phenylimidazole, the main product of the reaction is 1-methyl-5-(2-furyl)imidazole.

The vapour phase acylation of furan and pyrrole was carried out over HZSM‐5(19.7), HZSM‐5(30), HZSM‐5(280), CeHZSM‐5(30), LaHZSM‐5(30), HY and CeHY zeolites in a fixed bed reactor at atmospheric pressure using acetic anhydride as an acylating agent. The catalytic activity of the zeolite catalysts was dependent on the reaction temperature and the type of cation promoter used in the modification of the zeolite surface. The activity of the catalysts varied with the acidity of the zeloite systems tested. The yields of 2‐acetylfuran and 2‐acetylpyrrole with respect to the conversion of furan and pyrrole were 67.5% and 75.5% respectively. The acylation was found to be more active on Brønsted acidic sites available over zeolite systems.

The reactions of benzotrichloride with methyl and ethyl esters and nitriles of 2-thiophenecarboxylic and 2-furancarboxylic acids, with 2-acetylthiophene, 2-acetylfuran, and 2-thiophenaldehyde in the presence of an excess of anhydrous aluminum chloride have been studied. The phenyldichloromethyl group enters into position 4 of the thiophene and position 5 of the furan ring and on treating the reaction mixture with water is converted to benzoyl group.