Economia circular aplicada aos resíduos dos frutos de Citrus sinensis (L.)

Abstract

The circular economy is key to waste treatment, for example, the transformation of waste from the orange juice (Citrus sinensis) industry into first-rate products. The transformation of orange peel residues into essential oil boosts the bioeconomy. The objective was to evaluate the in vitro and in silico inhibitory potential against the enzyme acetylcholinesterase (AChE), investigate the antimicrobial effect, test the allelopathic effect on butter beans, analyze the antioxidant activity and insecticidal bioactivity by fumigation of the essential oil from C. sinensis (L.). The essential oil (EO) was extracted by hydrodistillation in a Cleveng apparatus and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). For antimicrobial action, the agar diffusion technique was used against the strains; Escherichia coli (ATC25922), Enterococcus faecalis (ATCC 29212), Candida albicans (ATCC 10231), Mycobacterium smegmatis (ATCC 14468), the allelopathic effect test used the application of contact treatment on beans, the antioxidant activity was measured through the tests of ABTS•+ and DPPH, the analysis of insecticidal bioactivity by fumigation was tested on adults of Sitophilus oryzae, and limonene as standard, with purity ≥ 95%, mortality readings were taken after 24, 48 and 72 hours. In CG-ME, 33 constituents from the class of monoterpenes and sesquiterpenes were identified, standing out as the majority; β-Citronelene (7.33%), β-Pinene (9.63%), Car-3-en-2-one (8.43%), Eugenol (4.24%), Limonene-10-ol ( 8.26%), α-Humulene (10.52%), α-neo-Cllovene (4.83%) and β-Acoradiene (12.47%). For antimicrobial action, EO showed inhibitory potential between low (+) and moderate (++). In the allelopathic test, changes were observed for the T4 dosage, 500µL of EO, between the root growth index and the germination speed of the bean seeds. In the ABTS•+ antioxidant capacity test, the EO demonstrated an IC50 of 0.951 ± 0.045 (μmol ET/mL), in the DPPH method, the EO did not exhibit antioxidant activity. In the fumigation test with EO, the corrected mortality rate was 6.7%, there was no significance in LC25% and for the highest dosages the phenomenon of hormoligosis occurred, the limonene standard presented a corrected mortality rate of 6.4 and 14.9% and CL25% of 19.75%, both within 48 hours. In the in vitro anticholinesterase test, the essential oil showed an inhibitory concentration value of IC50 =72 µg/mL, this result was corroborated with the in silico anticholinesterase test where it was possible to observe the inhibition of the acetylcholinesterase enzyme by the constituents β-citronelene, limonene, β-acoradiene and α-humulene, for the in silico result the binding energy values varied between -6.2 and -9.6 kcal/mol, values close to the galantamine inhibitor (redocking binding energy = -9.8 kcal/mol, RMSD 0.3678 Å). The results obtained suggest that EO from orange peels from the Amazon region has the ability to inhibit the enzyme acetylcholinesterase. These findings, in addition to exploring and elucidating the biological application of this oil, encourage the adoption of the circular economy, taking advantage of waste from juice industry. Not only contributing to minimizing waste, but also adding value to the final product, driving interest in its use in the areas of agriculture and medicine.