β-Pinene Derived Products With Enhanced In Vitro Antimicrobial Activity

Abstract

The development of new antimicrobials has always been a research hotspot. In this study, β-pinene-based derivatives were synthesized, and their antimicrobial activity was evaluated. The purpose was to develop some novel, promising new fungicides. Three β-pinene derivatives containing bis-hydronopyl were prepared, and their antifungal and antibacterial activities were evaluated against 6 plant pathogenic fungi and 4 bacterial species; a preliminary structure-activity relationship is discussed. The results indicated that the derivatives containing the blend of alkyl group and bis-hydronopyl had potent inhibitory activities against plant fungal pathogens and bacteria. Among these molecules, bis-hydronopyl dimethyl ammonium bromide showed excellent effects on Colletotrichum acutatum with a half-maximal effective concentration of 0.538 µg/mL, which was lower than that of carbendazim. Scanning electron microscope showed that after administration of bis-hydronopyl dimethyl ammonium bromide (compound 3a), the C. acutatum mycelia were sunken and deformed in comparison with the control group. Furthermore, the inhibitory activities of the methyl derivatives against the plant pathogens were better than those of the ethyl derivatives. These results provide new insights into the inhibition of fungi and bacteria by β-pinene derivatives, which may lead them to be used as precursor molecules for novel pesticides and antimicrobials in further research.

Design, Synthesis, Antibacterial, Antifungal and Anticancer Evaluations of Novel β-Pinene Quaternary Ammonium Salts

“…Zhong et al [25] found that the molecular weight, steric hindrance and alkyl chain length of the compound quaternary ammonium salts affected the antimicrobial activity. In our previous report, the antifungal activities of β-PQA salts with two methyl groups linked on the hydrophilic group N + were stronger than those compounds with the two ethyl groups [23]. We speculate that lower molecular weight and steric hindrance compounds are easier to absorb and diffuse through the cell membrane, which increases the chance of these compounds entering the bacteria or fungi to exert antibacterial or antifungal effects.…”

“…β-pinene is an important compound derived from plant essential oils, and its derivatives have significant research and development values on account of their wide range of pharmacological activities [13,21,22]. In our previous research, a series of quaternary ammonium salts were synthesized from β-pinene and we obtained many derivatives with potent antimicrobial activity [23]. However, no detailed studies have been investigated on its application in anticancer activities and antimicrobial mechanism.…”

“…Intermediate (1R, 2R, 5R)-hydronopyl halide (2a-2c) and (1R, 2R, 5R)-hydronopyl ammonium halide (3a-3c) were synthesized from β-pinene according to the process which was previously reported [23,36,37]. Then, the bis-hydronopyl quaternary ammonium salts (4a-4f) were obtained by the reaction between (1R, 2R, 5R)-hydronopyl halide (2a-2c, 0.05 M) and (1R, 2R, 5R)-hydronopyl ammonium halide (3a-3c, 0.05 M) in 30 mL ethyl acetate at 60 • C. After 48~72 h of reaction, the ethyl acetate was vacuum removed.…”

Highly Efficient Cationic Polymerization of β-Pinene, a Bio-Based, Renewable Olefin, with TiCl4 Catalyst from Cryogenic to Energy-Saving Room Temperature Conditions

“…The reactive exo methylene group in β-pinene makes it able to undergo carbocationic, and to a certain extent radical and coordinative polymerizations. It has to be noted that in addition to poly(β-pinene), this compound is used not only in a range of products, but as a starting material [ 15 , 27 , 28 , 29 , 30 , 31 , 32 ] or therapeutic agent [ 33 , 34 ], and it even has potential in COVID-19 treatment [ 35 ].…”

Synthesis and Antifungal Activity of Novel Tetrahydrogeranyl Quaternary Ammonium Salts

“…In recent years, quaternary ammonium salts have been reported to be used as fungicides because of their strong antifungal activity. [10][11][12][13][14][15] Feng et al [15][16][17] synthesized a series of quaternary ammonium salts with bridge ring structures using β-pinene as raw material and tested the antifungal activity of these compounds against plant pathogenic fungi. In this paper, citral was selected as the raw material to synthesize tetrahydrogeranyl quaternary ammonium salts through hydrogenation, bromination, amination, 18,19 and halogenation reactions, and the synthesized compounds contained tetrahydrogeranyl groups, N, N-diethyl, N,N-dimethyl, and N-morpholine groups.…”