ABSTRACT
The plant Momordica charantia (Cucurbitaceae), popularly known as bitter melon, snake fruit, Saint Vincent's herb, or little melon, is an African species that has developed in tropical and subtropical biomes in various parts of Brazil. The fruit is used in various traditional medicinal applications. The study aimed to identify the compounds of the essential oil of the leaves obtained by hydrodistillation and in the fruit through Solid-Phase Microextraction by headspace mode (HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). The analysis of mature fruits led to the identification of 18 compounds, compared to the hydrodistillation, in which 21 compounds were identified. Benzaldehyde, linalool, and ß-cyclocitral were identified in both methods. Linalool was the major compound in both processes. These findings highlight the importance of knowing the chemical composition of organic volatile compounds (VOCs), given the potential for medicinal applications and popular use of plants.
ABSTRACT
CONTEXT: Natural products and their biotransformation procedures are a powerful source of new chromophores with potential applications in fields like biology, pharmacology and materials science. Thus, this work discusses about the extraction procedure of 1-nitro-2-phenylethane (1N2PE) from Aniba canelilla, its biotransformation setup into 2-phenylethanol (2PE) using four fungi, Lasiodiplodia caatinguensis (phytopathogenic fungus from Citrus sinensis), Colletotrichum sp. (phytopathogenic fungus from Euterpe oleracea), Aspergillus flavus and Rigidoporus lineatus isolated from copper mining waste located in the interior of the Brazilian Amazon. A detailed experimental and theoretical vibrational analysis (IR and Raman) have allowed us to perform some charge transfer effects on the title compounds (push-pull effect) by monitoring specific vibrational modes of their electrophilic and nucleophilic molecular sites. The solvent interactions promote molecular conformations that affect the vibrational spectra of the donor and acceptor groups, as can be seen comparatively in the gas and aqueous solution spectra, an effect possibly related to the bathochromic shift in the calculated optical spectrum of the compounds. The nonlinear optical behavior shows that while the solvent reduces the response of 1N2PE, the response of 2PE increases the optical parameters, which presents low refractive index (n) and first hyperpolarizability. ([Formula: see text]) is almost eight times that reported for urea (42.79 a.u.), a common nonlinear optical material. Furthermore, the bioconversion goes from an electrophilic to a nucleophilic compound, affecting its molecular reactivity. METHODS: 1N2PE was obtained from Aniba canelilla, whose essential oil is constituted of [Formula: see text] of 2PE. The A. canelilla essential oil was extracted under hydrodistillation. The biotransformation reactions were performed in autoclaved liquid media (100 mL) composed of malt extract (2%) in 250 mL Erlenmeyer flask. Each culture was incubated in an orbital shaker (130 rpm) at [Formula: see text]C during 7 days and after that, 50 mg of 1N2PE (80%) were diluted in 100 [Formula: see text]L of dimethylsulfoxide (DMSO) and added to the reactions flasks. Aliquots (2 mL) were removed using ethyl acetate (2 mL) and analyzed by GC-MS (fused silica capillary col1umn, Rtx -5MS 30 m [Formula: see text] 0.25 mm [Formula: see text] 0.25 [Formula: see text]m) in order to determine the amount of 1N2PE biotransformation. FTIR 1N2PE and 2PE spectra were obtained by attenuated total reflectance (ATR), using a Agilent CARY 630 spectrometer, in the spectral region 4000-650 cm[Formula: see text]. The quantum chemical calculations were carried out in the Gaussian 09 program while the DICE code was used to perform the classical Monte Carlo simulations and generate the liquid environment using the classical All-Atom Optimized parameters for Liquid Simulations (AA-OPLS). All nonlinear optical properties, reactive parameters, and electronic excitations were calculated using the Density Functional Theory framework coupled to the standard 6-311++G(d,p) basis set.
