Pterodon emarginatus Seed Preparations: Antiradical Activity, Chemical Characterization, and In Silico ADMET Parameters of β-caryophyllene and Farnesol

Abstract

The study of medicinal plants and their active compounds is relevant to maintaining knowledge of traditional medicine and to the development of new drugs of natural origin with lower environmental impact. From the seeds of the Brazilian plant Pterodon emarginatus, six different preparations were obtained: essential oil (EO), ethanol extract (EthE) prepared using the traditional method, and four extracts using solvents at different polarities, such as n-hexane, chloroform, ethyl acetate, and methanol (HexE, ChlE, EtAE, and MetE). Chemical characterization was carried out with gas chromatography, allowing the identification of several terpenoids as characteristic components. The two sesquiterpenes β-caryophyllene and farnesol were identified in all preparations of Pterodon emarginatus, and their amounts were also evaluated. Furthermore, the total flavonoid and phenolic contents of the extracts were assessed. Successively, the antiradical activity with DPPH and ORAC assays and the influence on cell proliferation by the MTT test on the human colorectal adenocarcinoma (HT-29) cell line of the preparations and the two compounds were evaluated. Lastly, an in silico study of adsorption, distribution, metabolism, excretion, and toxicity (ADMET) showed that β-caryophyllene and farnesol could be suitable candidates for development as drugs. The set of data obtained highlights the potential medicinal use of Pterodon emarginatus seeds and supports further studies of both plant preparations and isolated compounds, β-caryophyllene and farnesol, for their potential use in disease with free radical involvement as age-related chronic disorders.

Keywords: ADMET; ADMETlab web tool; DPPH assay; ORAC assay; antioxidants; essential oil; gas chromatography; medicinal plants; phenols; terpenes; traditional medicine.

Figure 1

Chemical structures of β-caryophyllene and farnesol, two characteristic compounds detected in essential oil and extracts obtained from Pterodon emarginatus seeds.

Figure 2

An example of a gas chromatogram of essential oil obtained from the seeds of Pterodon emarginatus. (IS): internal standard (1,3,5-triisopropylbenzene, Rt = 16.11); (1): β-caryophyllene (Rt = 26.88 min); (2) farnesol (Rt = 39.35 min).

Figure 3

The phenolic (A) and flavonoid (B) contents of various Pterodon emarginatus extracts, including the ethanol extract (EthE), obtained with the method used in traditional Brazilian medicine, and the ethyl acetate and methanol extracts (EtAE and MetE), obtained with sequential extraction. For essential oil (EO), n-hexane, and chloroform extracts, the quantity of phenols and flavonoids was not measurable. The data are the mean ± SEM of 5–6 experiments. GAE: gallic acid equivalents; QE: quercetin equivalents; ^§§: p < 0.01 versus EthE (A); **: p < 0.01 versus EthE (B); °°: p < 0.01 versus EtAE; °°°°: p < 0.0001 versus EthE; ****: p < 0.0001 versus EtAE.

Figure 4

Radical scavenging activity of essential oil (EO), ethanol extract (EthE), hexane extract (HexE), chloroform extract (ChlE), ethyl acetate extract (EtAE), and methanol extract (MetE) of Pterodon emarginatus seeds, and of β-caryophyllene and farnesol detected by DPPH (A) and ORAC (B) assays. Ascorbic acid was the positive control for antiradical activity. Undisclosed SEM fall within the respective symbols (A). The ORAC values are expressed as TEAC (Trolox Equivalent Antioxidant Capacity), μmol of Trolox equivalents per gram of each extract or compound. **: p < 0.01 methanol extract versus each extract or compound; °°: p < 0.01 β-caryophyllene or farnesol versus ascorbic acid and versus each extract; °: p < 0.05 EthE versus ascorbic acid; °°°°: p < 0.0001 MetE versus ascorbic acid.

Figure 5

The effects of essential oil (EO), ethanol extract (EthE), hexane extract (HexE), and methanol extract (MetE) of Pterodon emarginatus seeds, and caryophyllene and farnesol on HT-29 cell viability were detected by the MTT assay. **: p < 0.01, and ***: p < 0.001 versus control (not treated cells). Chloroform and ethyl acetate extracts were not tested due to problems with their solubility in cell medium and the low quantity obtained during the extraction process (EtAE).