Derivatization of Natural Compound β-Pinene Enhances Its In Vitro Antifungal Activity against Plant Pathogens

Abstract

Background: The development of new antifungal agents has always been a hot research topic in pesticide development. In this study, a series of derivatives of natural compound β-pinene were prepared, and the antifungal activities of these derivatives were evaluated. The purpose of this work is to develop some novel molecules as promising new fungicides. Methods: Through a variety of chemical reactions, β-pinene was transformed into a series of β-pinene-based derivatives containing amide moieties and acylthiourea moieties. The antifungal activities of these derivatives against five plant pathogens including Colletotrichum gloeosporioides, Fusarium proliferatum, Alternaria kikuchiana, Phomopsis sp. and Phytophthora capsici were tested; preliminary structure–activity relationship was discussed. Results: Some derivatives exhibited moderate or significant antifungal activity due to the fusion of the amide moiety or the acylthiourea moiety with the pinane skeleton. The structure–activity relationship analysis showed that the fluorine atom and the strong electron withdrawing nitro group, or trifluoromethyl group on the benzene ring of the derivatives had a significant effect on the improvement of the antifungal activity against Colletotrichum gloeosporioides, Fusarium proliferatum, Alternaria kikuchiana and Phomopsis sp. Meanwhile, the introduction of an ethyl group at the meta-position on the benzene ring of the derivatives could improve the antifungal activity against Phytophthora capsici. Compounds 4e, 4h, 4q, 4r exhibited broad-spectrum antifungal activity against the tested strains. Compound 4o had significant antifungal activity against Phytophthora capsici (IC50 = 0.18 μmol/L). These derivatives were expected to be used as precursor molecules for novel pesticide development in further research.

Essential Oils of Lamiaceae Family Plants as Antifungals

“…Rich in these substances are, among others Origanum and Thymus plants. Important antifungal chemicals often presented in Lamiaceae are also other monoterpenes as alcohol linalool and cyclic 1,8-cineole, limonene, pinenes, and terpinenes [138][139][140][141][142][143][144][145][146]. Table 1 shows that all of these antifungal substances are common in presented plants.…”

“…Additionally, many other factors can affect antimicrobial activity, such as amount and concentration of inoculum, type of culture medium, pH of the medium and incubation time. All these factors can affect the value of MIC [145]. Differences are visible in Table 2.…”

An amino acid ester of menthol elicits defense responses in plants

“…Moving forward, derivatives of PSMs will be highly useful for biogenic, biochemical and pharmacological objectives, as shown previously in the development of aspirin (from salicin) as an analgesic/painkiller (Stahelin and von Wartburg 1991), naloxone and oxycodone (from thebaine) as an analgesic/painkiller (Morlion et al 2018), irinotecan (from camptothecin) as an anticancer agent (Tsuruo et al 1988), docetaxel (from taxol) as an anticancer agent (Pazdur et al 1993), and etoposide (from podophyllotoxin) as an anticancer agent (Stahelin and von Wartburg 1991), and so on. However, derivatives of VOCs have not been commercially developed for use as pharmacological or health-promoting agents or for use in agriculture or horticulture, except in some cases of their use for academic explorations (Samarasekera et al 2008, Nesterkina and Kravchenko 2017, Shi et al 2019).…”

Weathering of Antibacterial Melt-Spun Polyfilaments Modified by Pine Rosin

“…For PLA with rosin (fPLA10 series), also propanoic acid was observed, expectedly. In addition, limonene and pinene (monoterpenes) were found and these terpene molecules are typical in plant essential oils as well as in pine rosin [ 25 , 28 , 37 ]. A minor limonene trace was also found for the fPLA10 series.…”

“…The chemical content of rosin (resin) depends naturally on the exact tree species, the part of tree being used and the extraction process [ 19 , 20 , 21 ]. Rosin alone or its derivatives as well rosin as additive in various polymeric systems have been proven antimicrobial against several Gram-positive and Gram-negative bacteria [ 22 , 23 , 24 ] and fungi [ 25 , 26 , 27 ]. Even when rosin is externally subject to living organisms, it can form low-molecular weight emissions (volatile organic compounds, VOCs) that could be defined as harmful in large quantities [ 28 , 29 ].…”