Study on the mechanisms of the antibacterial action of some plant alpha,beta-unsaturated aldehydes

Abstract

Aims: In this paper the mechanisms involved in the antibacterial effect of six 2E-alkenals [(E)-2-hexenal, (E)-2-eptenal, (E)-2-octenal, (E)-2-nonenal, (E)-2-decenal and (E,E)-2,4-decadienal] were investigated. Methods and Results: We measured the release of carboxyfluorescein (CF) trapped in liposomes of phosphatidylcholine (PC) following exposure to the aldehydes mentioned above, in comparison with that elicited by hexanal and nonanal; the modifications of the thermotropic behaviour of liposomes of dimyristoylphosphatidylcholine (DMPC) induced by (E,E)-2,4-decadienal (the aldehyde endowed with the highest microbicidal activity) were evaluated by means of differential scanning calorimetry. With the exception of hexanal, all aldehydes tested caused rapid CF leakage from PC liposomes. The effectiveness order correlates well with the chain length and the presence of the a,b-double bond. Furthermore (E,E)-2,4-decadienal is able to interact with and cross DMPC bilayers. Conclusions: The present findings suggest that the 2E-alkenals tested elicit, very likely, a gross perturbation of the lipidic fraction of plasmatic membranes and are able to penetrate into bacterial cells. Significance and Impact of the Study: These data represent an interesting background for a rational employment of the plant 2E-alkenals tested as antimicrobial agents.

Naturally Occurring Antifungal Agents and Their Modes of Action

“…Interestingly, 2E-alkenals tested caused rapid CF leakage from PC liposomes and the effectiveness order correlated well with the alkyl chain length. Thus, 2E-nonenal was more effective in inducing CF leakage from PC liposomes than that of 2E-hexenal (Trombetta et al, 2002). This also supports the surfactant concept.…”

“…The leakage of carboxyfluorescein (CF) in liposomes of phosphatidylcholine (PC) following exposure to 2E-alkenals was previously reported (Trombetta et al, 2002), similar to those described for alkyl gallates . Interestingly, 2E-alkenals tested caused rapid CF leakage from PC liposomes and the effectiveness order correlated well with the alkyl chain length.…”

Mechanisms of Antibacterial Action of Three Monoterpenes

“…In the present study, we monitored the release of CF trapped in LUVs with different lipid composition (PC, PC/PS [9:1], PC/SA [9:1], and PG/CL [9:1]) following exposure to the terpenes under investigation (9,24). Briefly, multilamellar liposome vesicles (MLVs) were obtained by freshly prepared chloroform/methanol concentrated lipid solutions.…”

Synergistic fungicidal efficacy of formulations of neem oil, nicotinic acid and Ferula asafoetida with .ALPHA., .BETA.-unsaturated carbonyl compounds against Sclerotium rolfsii ITCC 5226 & Macrophomina phaseolina ITCC 0482

“…neem oil (Azadirachta indica) (N1), nicotinic acid (N2) and Ferula asafoetida (N3), used in the current study have been well documented for their wide range of applications in agriculture and pharmacology, [11][12][13][14][15][16] suggesting their biocompatibility with the environment as well as with humans and other mammals. Further, synthetic constituents selected for investigation possess i) a carbonyl group in conjugation with a double bond as this is reported to have a profound effect on the activity of various pharmacologically important compounds, 17,18) and ii) a basic chalcone nucleus (1c-1i), as several naturally occurring and synthetic compounds with chalcone as the core nucleus have been reported to have broad spectrum biological activity, 19) such as insecticidal, 20) antifungal, 21) antioxidant, [22][23][24] tyrosinase inhibitory, antimitotic, 26) and antibacterial activity. 27,28) In addition, all of the compounds can be synthesized easily at ambient temperature and pressure with minimum use of hazardous chemicals.…”