A new alkaloid and a new benzaldehyde derivative from the twig of Zanthoxylum rhetsa (Roxb.) DC

A new alkaloid, 2-acetyl-4-methoxyfuro[2,3-b]quinoline (1), and a new benzaldehyde derivative, (2'S)-4-(2'-hydroxy-3'-methyl-3'-butenoxy)benzaldehyde (2), were isolated from the twig of Zanthoxylum rhetsa (Roxb.) DC. along with twenty-six known compounds (3-28). Their structures were determined by spectroscopic analysis (1D and 2D NMR spectroscopy and HRMS analysis) and comparison with data reported in the literature. Thirteen of the known compounds were evaluated for their cytotoxic activities against human cancer cell lines that included MDA-MB-231, SW1353, A549, and HCT116. (±)-8-Acetonyldihydronitidine (15) showed moderate cytotoxicity toward the SW1353 cancer cell line with an IC50 value of 18.90±0.39 µg/mL, and exhibited weak cytotoxic activity against MDA-MB-231, A549 and HCT116 cell lines with IC50 values of 49.86-71.32 µg/mL.

A New Benzaldehyde Derivative Exhibits Antiaflatoxigenic Activity against Aspergillus flavus

Aflatoxin B1 (AFB1) is the most potent naturally occurring carcinogen for humans and animals produced by the common fungus Aspergillus flavus (A. flavus). Aflatoxin (AF) contamination in commodities is a global concern related to the safety of food and feed, and it also impacts the agricultural economy. In this study, we investigated the AFB1-inhibiting activity of a new benzaldehyde derivative, 2-[(2-methylpyridin-3-yl)oxy]benzaldehyde (MPOBA), on A. flavus. It was found that MPOBA inhibited the production of AFB1 by A. flavus, with an IC50 value of 0.55 mM. Moreover, the inhibition of conidiation was also observed at the same concentration. The addition of MPOBA resulted in decreased transcript levels of the aflR gene, which encodes a key regulatory protein for the biosynthesis of AF, and also decreased transcript levels of the global regulator genes veA and laeA. These results suggested that MPOBA has an effect on the regulatory mechanism of the development and differentiation of conidia, leading to the inhibition of AFB1 production. In addition, the cytotoxicity study showed that MPOBA had a very low cytotoxic effect on the Madin-Darby canine kidney (MDCK) cell line. Therefore, MPOBA may be a potential compound for developing practically effective agents to control AF contamination.

Synthesis of Dihydropyrimidinones (DHPMs) and Hexahydro Xanthene Catalyzed by 1,4-Diazabicyclo [2.2.2] Octane Triflate Under Solvent-Free Condition

OBJECTIVE

DABCO salts were evaluated as catalysts for the Biginelli reaction between 4- methoxybenzaldehyde, urea and ethyl acetoacetate under solvent-free conditions. 1,4-Diazabicyclo [2.2.2] octane triflate was found to be a simple, inexpensive, highly efficient catalyst for Biginelli reaction for a variety aromatic aldehyde with urea and ethyl acetoacetate at 80°C afforded corresponding 3,4-dihydropyrimidinones in 50-99% yields after 30-120 minutes. 1,3-Cyclohexadione was used in place of ethyl acetoacetate in the absence of urea this methodology is giving hexahydro xanthene derivatives in good to excellent yields after 3-4 hours.

METHODS

DABCO salt 4 (5 mol%), 4-methoxybenzaldehyde (0.73 mmol) and urea (0.73 mmol) were stirred for 10 minutes at 80°C, then ethyl acetoacetate (1.5 equiv.) was added and reaction mixture was stirred at 80°C for specified time. The resulting solution was stirred continuously and progress of the reaction was followed by TLC. The crude reaction mixture was purified by flash column chromatography on silica gel (hexane/ethyl acetate (1:2)) to give pure desired product.

RESULTS

Reaction conditions of the Biginelli reaction were optimized using 4-methoxybenzaldehyde (0.73 mmol), urea (0.73 mmol), and ethyl acetoacetate (5 equiv.) as model substrates catalyzed by 1,4-Diazabicyclo [2.2.2] octane triflate (5 mol%) in a different solvents, screening of different catalysts and different temperatures. Neat condition was found to be the best for the Biginelli condensation and corresponding 3,4- dihydropyrimidinones was obtained in good to excellent yields. When the reaction was carried out with benzaldehyde derivatives and cyclohexane-1,3-dione in place of ethyl acetoacetate in the absence of urea, solely corresponding hexahydro xanthene derivatives were obtained in 61-91% yields.

CONCLUSION

In conclusion, we have applied salts of 1,4-Diaza-bicyclo [2.2.2] octane as catalysts in the Biginelli condensation and corresponding 3,4-dihydropyrimidinones were obtained in 50- 99% yields under solvent free conditions. This methodology is having advantages like simple work-up; low loading of catalyst and reaction was performed at moderate temperature under solvent-free conditions.

fungus

Two new benzaldehyde derivatives, named 3'-OH-tetrahydroauroglaucin (1) and(3'S*,4'R*)-6-(3',5-epoxy-4'-hydroxy-1'-heptenyl)-2-hydroxy-3-(3''-methyl-2''-butenyl)benzaldehyde (2), were isolated from a gorgonian-derived Eurotium sp. fungus. Their structures were determined by extensive spectroscopic analysis including NMR and MS spectra. Dissolved 1 in CDCl₃ for several days could be detected its 2H-chromene skeleton derivatives (1a/1b), a pair of enantiomers with opposite configurations at C-3'. Compound 2 was also found to chemically convert to a pair of epimers non-enzymatically. The plausible mechanism to form the 2H-chromene artefacts with racemisation at C-3' undergoing nucleophilic substitution (S_N1) was proposed.