Chemometrics of the Composition and Antioxidant Capacity of Hyptis crenata Essential Oils from Brazil.

Hyptis crenata (Pohl) ex Benth is used in traditional medicine as an analgesic to treat general pain. Six Hyptis crenata samples (Hc-1 to Hc-6) were collected in Pará state, Brazil. The leaf essential oils were obtained by hydrodistillation, and GC-MS and GC-FID were used to analyze their chemical compositions. The antioxidant capacity was measured in vitro using DPPH and carotene/linoleic acid assays. Chemometrics analysis (PCA, HCA, and clustered heat map) were used to identify the sample relationships between those collected in this study and those from the literature (Hc-7 to Hc-16) samples. According to the main chemical constituents identified in the samples described in this work and the literature, the sixteen samples were classified into ten groups. Group I was characterized by 1,8-cineole (31.0%), α-pinene (13.6%), (E)-caryophyllene (7.8%), and ß-pinene (7.6%); and Group IV was characterized by 1,8-cineole (17.4-23.5%), α-pinene (15.7-23.5%), ß-pinene (10.5-13.4%), and limonene (8.5-9.7%). Both groups are described for the first time. The total antioxidant capacity was expressed in Trolox Equivalent Antioxidant Capacity values (TEAC): TEAC of Hc-5 (551.9 mg.TE/g) and Hc-6 (475.1 mg.TE/g). In the ß-carotene/linoleic acid assay, the highest inhibition was from Hc-2 (40.0%), Hc-6 (39.0%), and Hc-3 (29.4%).

Monoterpenes and Sesquiterpenes of Essential Oils from Psidium Species and Their Biological Properties.

Psidium (Myrtaceae) comprises approximately 266 species, distributed in tropical and subtropical regions of the world. Psidium taxa have great ecological, economic, and medicinal relevance due to their essential oils' chemical diversity and biological potential. This review reports 18 Psidium species growing around the world and the chemical and biological properties of their essential oils. Chemically, 110 oil records are reported with significant variability of volatile constituents, according to their seasonality and collection sites. Monoterpenes and sesquiterpenes with acyclic (C10 and C15), p-menthane, pinane, bisabolane, germacrane, caryophyllane, cadinane, and aromadendrane skeleton-types, were the primary constituents. The essential oils showed various biological activities, including antioxidant, antifungal, antibacterial, phytotoxic, larvicidal, anti-inflammatory, and cytotoxic properties. This review contributes to the Psidium species rational and economic exploration as natural sources to produce new drugs.

Essential Oils as Antiviral Agents. Potential of Essential Oils to Treat SARS-CoV-2 Infection: An In-Silico Investigation.

Essential oils have shown promise as antiviral agents against several pathogenic viruses. In this work we hypothesized that essential oil components may interact with key protein targets of the 2019 severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A molecular docking analysis was carried out using 171 essential oil components with SARS-CoV-2 main protease (SARS-CoV-2 Mpro), SARS-CoV-2 endoribonucleoase (SARS-CoV-2 Nsp15/NendoU), SARS-CoV-2 ADP-ribose-1″-phosphatase (SARS-CoV-2 ADRP), SARS-CoV-2 RNA-dependent RNA polymerase (SARS-CoV-2 RdRp), the binding domain of the SARS-CoV-2 spike protein (SARS-CoV-2 rS), and human angiotensin-converting enzyme (hACE2). The compound with the best normalized docking score to SARS-CoV-2 Mpro was the sesquiterpene hydrocarbon (E)-ß-farnesene. The best docking ligands for SARS-CoV Nsp15/NendoU were (E,E)-α-farnesene, (E)-ß-farnesene, and (E,E)-farnesol. (E,E)-Farnesol showed the most exothermic docking to SARS-CoV-2 ADRP. Unfortunately, the docking energies of (E,E)-α-farnesene, (E)-ß-farnesene, and (E,E)-farnesol with SARS-CoV-2 targets were relatively weak compared to docking energies with other proteins and are, therefore, unlikely to interact with the virus targets. However, essential oil components may act synergistically, essential oils may potentiate other antiviral agents, or they may provide some relief of COVID-19 symptoms.

Xanthones from the roots of Moutabea guianensis Aubl.

The phytochemical investigation of Moutabea guianensis roots led to the isolation of five polyoxygenated xanthones, including two new ones named moutabeone B (1,8-dihydroxy-4,5,6,7-tetramethoxyxanthone) and moutabeone C (1-hydroxy-4,5,6,7,8-pentamethoxyxanthone), along with the three known xanthones, 1,8-dihydroxy-4,6-dimethoxyxanthone, 1,8-dihydroxy-4,5,6-trimethoxyxanthone and augustin A (1,8-dihydroxy-4,6,7-trimethoxyxanthone). Structural characterization of all compounds was established on the basis of spectroscopic methods, mainly 1D and 2D nuclear magnetic resonance (NMR) and comparison with literature data. The antioxidant activity of compounds was tested through a thin layer chromatography (TLC) bioautography assay using 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH·) as detection reagent. All tested compounds were more active (DL < 0.13-0.03 µg) than Trolox (DL < 0.15 µg), used as reference standard.

Antioxidant capacity and biological activity of essential oil and methanol extract of Hyptis crenata Pohl ex Benth / Capacidade antioxidante e atividade biológica do óleo essencial e extrato metanólico de Hyptis crenata Pohl ex Benth

O óleo essencial das folhas e ramos finos frescos e secos de Hyptis crenata forneceu os seguintes rendimentos, 1,4 por cento e 0,9 por cento. Os constituintes voláteis principais foram ±-pineno (22,0 por cento; 19,5 por cento), 1,8-cineol (17,6 por cento; 23,2 por cento), ²-pineno (17,0 por cento: 13,8 por cento), cânfora (4,7 por cento; 11,6 por cento), limoneno (5,4 por cento; 4,4 por cento) e ³-terpineno (3,5 por cento; 2,4 por cento), totalizando mais de 70 por cento nos óleos. A atividade de seqüestro do radical DPPH para o extrato metanólico (CE50, 16,7 + 0,4 µg/mL) foi comparável ao do BHT (19,8 ± 0,5 µg/mL) mostrando uma significante atividade antioxidante. Os óleos apresentaram baixa atividade. O teor de fenólicos totais (TP, 373,0 + 15,9 mg GAE/g) e equivalente trolox (TEAC, 226,8 + 0,5 mg TE/g) confirmaram a atividade antioxidante do extrato metanólico, que pode ser atribuída à presença de compostos fenólicos polares. No teste com larvas de camarão as concentrações letais para o óleo e extrato metanólico foram 6,7 + 0,2 µg/mL e 13,0 + 3,7 µg/mL, respectivamente, fornecendo importante evidência de suas atividade biológicas.

The essential oils of fresh and dried leaves and fine stems of Hyptis crenata furnished the following yields: 1.4 percent and 0.9 percent. The main volatile constituents were ±-pinene (22.0 percent; 19.5 percent), 1,8-cineole (17.6 percent; 23.2 percent), ²-pinene (17.0 percent; 13.8 percent), camphor (4.7 percent; 11.6 percent), limonene (5.4 percent; 4.4 percent) and ³-terpinene (3.5 percent; 2.4 percent), totalizing more than 70 percent in the oils. The DPPH radical scavenging activity (EC50, 16.7 + 0.4 µg/mL) of the methanol extract was comparable to BHT (19.8 ± 0.5 µg/mL) showing a significant antioxidant activity. The oils showed low activities. The amount of total phenolics (TP, 373.0 + 15.9 mg GAE/g) and trolox equivalent (TEAC, 226.8 + 0.5 mg TE/g) confirmed the antioxidant activity of the methanol extract that can be attributed to the presence of polar phenolic compounds. In the brine shrimp bioassay the lethal concentrations (LC50) for the oil and methanol extract were 6.7 + 0.2 µg/mL and 13.0 + 3.7 µg/mL, respectively, providing important evidence of their biological activities.