Chemical composition and antifungal activity of the essential oil from the Hymenaea stigonocarpa Mart. Ex Hayne (jatobá-do-cerrado) fruit peel

Abstract This study investigated the chemical composition and the antifungal activity of the essential oil extracted from the Hymenaea stigonocarpa fruit peel (HSFPEO) against Botrytis cinerea, Sclerotinia sclerotiorum, Aspergillus flavus and Colletotrichum truncatum. The HSFPEO obtained through hydrodistillation was analyzed with gas chromatography coupled to mass spectrometry. The antifungal activity was determined by the mean mycelial growth inhibition of the fungus treated with essential oils and growth control. The major constituents of HSFPEO were spathulenol (25.19%) and caryophyllene oxide (13.33%). HSFPEO demonstrated antifungal activity against all fungi tested in all concentrations evaluated in a dose-dependent behavior. The best results were observed against B. cinerea and A. flavus, in which the lowest concentration tested inhibited more than 70% of mycelial growth. Based on the current knowledge, this study describes for the first time the chemical composition and the antifungal activity of HSFPEO against the phytopathogenic fungi B. cinerea and C. truncatum. Graphical Abstract


Introduction
phytopathogenic fungi are one of the main infectious agents in plants, inflicting significant economic and production losses.among the fungal pathogens, Botrytis cinerea is one of the most damaging as it affects a large range of plants, causing the grey mold disease on vegetables and fruits, such as tomatoes and strawberries (Rguez et al. 2020).Sclerotinia sclerotiorum is the causative agent of the white mold disease, with a high potential to cause damage to soybean, sunflower, tomato and other economically important crops (Barbacci et al. 2020).Aspergillus flavus is a fungal species that produces aflatoxins, such as aflatoxin B1 and aflatoxin B2, and that can affect several agricultural products, such as rice, corn, peanuts, spices and dried fruits (Bomfim et al. 2020).another disease that affects important crops, such as soybean, is anthracnose, produced by Colletotrichum truncatum (Soto et al. 2020).
natural substances, such as essential oils, have been shown as promising in the search for alternatives to synthetic fungicides in the phytopathogens control, since studies have demonstrated their fungicidal potential (nazzaro et al. 2017).
Jatobá-do-cerrado (Hymenaea stigonocarpa mart.Ex Hayne) is a legume tree native of the Brazilian savannah.previous studies have shown that the essential oil present in its leaves and bark acts as an antifungal, antibacterial and molluscidal agent (menezes Filho et al. 2020).phytochemical studies of H. stigonocarpa showed the presence of terpenes, flavonoids and tannins in different parts of the tree (dimech et al. 2013; maranhão et al. 2013; monteiro et al. 2015).
in this context, the present study aimed to carry out the chemical study of the essential oil from the fruit peel of H. stigonocarpa and to evaluate its antifungal activity on Botrytis cinerea, Sclerotinia sclerotiorum, Aspergillus flavus and Colletotrichum truncatum.

Results and discussion
the essential oil from the H. stigonocarpa fruit peel (HSFpEo) obtained with 180 min of extraction was analyzed by gas chromatography/mass spectrometry with yields ranging from 0.297% ± 0.08 (30 min) to 0.915% ± 0.05 (210 min) (table S1).With 180, 210 and 240 min, the yield obtained from HSFpEo extraction was higher than in the other experiments, but the extracted content did not differ statistically between these three times.thus, it is possible to suggest that the hydrodistillation time of 180 min (0.890% ± 0.02 yield) is the best to be used because it presents good yield and shorter extraction time.
a total of 30 different volatile compounds were identified (table S2). the major compounds were the oxygenated sesquiterpenes spathulenol (25.19%) and caryophyllene oxide (13.33%) (Figure S1).these results corroborate with previous studies in which sesquiterpenes were identified as the main constituents of the essential oils from Hymenaea species, such as H. courbaril (aguiar et al. 2010;Costa et al. 2017;Santos et al. 2022), H. rubriflora (Silva et al. 2021) and H. cangaceira (Veras et al. 2020).the fungicidal activity of essential oils rich in spathulenol and caryophyllene oxide has been reported in the literature.the essential oil of Artemisia argyi Lévl.et Vant inflorescence exhibited antifungal activity against Botrytis cinerea and Alternaria alternate (Wenqiang et al. 2006).the essential oils obtained through hydrodistillation of barks of Enantia chlorantha (annonaceae) present a significant activity against six fungal strains, among which is A. flavus (nyegue et al. 2008).
the percentages of mycelial growth inhibition of Botrytis cinerea, Sclerotinia sclerotiorum, Aspergillus flavus and Colletotrichum truncatum by the essential oil from the H. stigonocarpa fruit peel (hydrodistillation time of 180 min) are shown in Figures S2-S5. the HSFpEo demonstrated antifungal activity against all fungi tested in all concentrations evaluated in a dose-dependent behavior.the most promising results were observed against B. cinerea and A. flavus, in which the lowest concentration tested (10 µL mL −1 ) inhibited 73.66% and 82.83%, respectively, of mycelial growth, and the highest concentration (100 µL mL −1 ) completely inhibited the fungi growth.For these fungi, the concentrations of 70 and 100 µL mL −1 did not differ statistically from the positive controls.For S. sclerotiorum, the inhibition of mycelial growth was greater than 90% from a dose of 50 µL mL −1 .at concentrations of 150 and 200 µL mL −1 , the inhibition was 99.66% and 100%, respectively, with no statistical difference between them and from the positive control.against C. truncatum, the concentration of 200 µL mL −1 of HSFpEo inhibited 96.5% of mycelial growth.
menezes Filho et al. ( 2020) evaluated the fungicidal potential of the essential oil from the H. stigonocarpa fruit peel against A. flavus and S. sclerotiorum and observed a maximum inhibition of 55% and 83%, respectively, at the highest concentration evaluated (100 µL mL −1 ).although these authors have not reported the chemical composition of the essential oil, they are likely to present differences in the composition in relation to what is presented in this work, which justifies the differences in the mycelial growth inhibition.

Experimental
See Supplementary material.

Conclusion
the analysis of the essential oil extracted from the H. stigonocarpa fruit peel showed that sesquiterpenes were the predominant constituents, with spathulenol and caryophyllene oxide being the main identified compounds.Regarding antifungal activity, HSFpEo demonstrated antifungal potential against Botrytis cinerea, Sclerotinia sclerotiorum, Aspergillus flavus and Colletotrichum truncatum in all concentrations evaluated in a dose-dependent behavior.this work describes for the first time the chemical composition and antifungal activity of HSFpEo against the phytopathogenic fungi B. cinerea and C. truncatum, contributing to the knowledge of the species, as well as to its application.

Disclosure statement
no potential conflict of interest was reported by the authors.