Biological assessment (antiviral and antioxidant) and acute toxicity of essential oils from Drimys angustifolia and D. brasiliensis

Chemical Profiling of Drimys granadensis (Winteraceae) Essential Oil, and Their Antimicrobial, Antioxidant, and Anticholinesterase Properties

A complete and comprehensive chemical and biological study of Drimys granadensis, a native Ecuadorian aromatic plant, was conducted. By conventional steam distillation from dried leaves, a yellowish, translucent essential oil (EO) with a density of 0.95 and a refractive index of 1.5090 was obtained. The EO was analyzed by gas chromatography coupled to a mass spectrometer (GC/MS) and an FID detector (GC/FID), respectively. Enantiomeric distribution was also carried out by GC/MS using a chiral selective column (diethyl tert-butylsilyl-BETA-cyclodextrin). The microdilution broth method was employed to assess the antibacterial and antifungal activity of the EO against a panel of opportunistic microorganisms. Antioxidant capacity was measured using diphenyl picryl hydrazyl (DPPH) and azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radicals. Finally, the inhibitory potential of the EO against acetylcholinesterase was also valued. Sixty-four chemical compounds, constituting 93.27% of the total composition, were identified, with major components including γ-muurolene (10.63%), spathulenol (10.13%), sabinene (5.52%), and δ-cadinene (4.22%). The characteristic taxonomic marker of the Drimys genus, Drimenol, was detected at very low percentages (<2%). Two pairs of enantiomers ((1S,5R)-(+)-α-pinene/(1S,5S)-(-)-α-pinene; (1S,5R)-(+)-β-pinene/(1S,5S)-(-)-β-pinene) and one pure enantiomer (1R,4S)-(-)-camphene were identified. Regarding antimicrobial potency, the EO exhibited a significant moderate effect on Listeria monocytogenes with a minimal inhibitory concentration (MIC) value of 250 µg/mL, while with the remaining microorganisms, it exerted less potency, ranging from 500 to 2000 µg/mL. The EO displayed moderate effects against the ABTS radical with a half scavenging capacity of 210.48 µg/mL and no effect against the DPPH radical. The most notable effect was noticed for acetylcholinesterase, with a half inhibition concentration (IC50) of 63.88 ± 1.03 µg/mL. These antiradical and anticholinesterase effects hint at potential pharmacological applications in Alzheimer's disease treatment, although the presence of safrole, albeit in low content (ca. 2%), could limit this opportunity. Further in vivo studies are necessary to fully understand their potential applications.

Oral acute and subchronic toxicity studies of the oil extracted from pequi (Caryocar brasiliense, Camb.) pulp in rats

The Caryocar brasiliense (pequi) is a Brazilian fruit of important geographic distribution and of broad popular use for nutritional purposes. This study aimed to evaluate the toxicological potential of pequi through the acute and subchronic toxicity tests. For the acute toxicity test, female Wistar rats received, orally, a single dose of 2000 mg/kg/bw of pequi oil and were observed for 14 days. In subchronic toxicity test, Wistar male and female rats received, orally, repeated doses of 125, 250, 500 or 1000 mg/kg/bw of the oil, being treated and observed for 28 days. In the acute toxicity test, no changes as well as no mortality were observed, indicating that the LD₅₀ is higher than 2000 mg/kg/bw. In the subchronic toxicity test, the tested doses produced no significant changes in behavioral, physiological, biochemical or histopathologic parameters in animals. Some hematological abnormalities were found after subchronic exposure and need to be clarified. These results demonstrate the low toxicity of acute and subchronic to the oil of pequi in rats. However, additional studies are required in order to verify if the hematological abnormalities have any relation to the oil exposure and also provide sufficient safety evidence for the use of the oil in humans.

Acute and subacute (28 days) oral toxicity assessment of the oil extracted from Acrocomia aculeata pulp in rats

Acrocomia aculeata, popularly known as “bocaiúva”, is a species used for nutritional purposes and for the treatment of various diseases, as it has, among other things, high levels of antioxidant compounds. This study aimed to assess the toxicological profile of A. aculeata, through acute and subacute toxicity tests. Male and female rats (Wistar) received by gavage 2000 mg/kg of oil extracted from the pulp of A. aculeata (OPAC) for the acute toxicity test and 125, 250, 500 or 1000 mg/kg of OPAC for subacute toxicity test. In the acute toxicity study no mortality or behavioral changes were observed in rats treated with 2000 mg/kg, indicating that the LD50 is higher than this dose. In the subacute toxicity test, the tested doses produced no significant changes in hematological, biochemical or histopathological parameters in the animals exposed. These results demonstrate the absence of acute and subacute toxicity after oral exposure to A. aculeata oil in rats. However, further studies in animals and in humans are needed in order to have sufficient safety evidence for its use in humans.