The chemical composition and biological activity of essential oils isolated from the leaves of Siparuna aspera, Siparuna macrotepala, Piper leticianum, Piper augustum and the rhizome of Hedychium coronarium were evaluated. These species are used medicinally in different ways by the Amazonian communities that live near the Kutukú mountain range. Chemical studies revealed that the main components for the two Siparuna species were germacrene D, bicyclogermacrene, α-pinene, δ-cadinene, δ-elemene, α-copaene and β-caryophyllene; for the two Piper species β-caryophyllene, germacrene D, α-(E,E)-farnesene, β-elemene, bicyclogermacrene, δ-cadinene and for H. coronarium 1,8-cineole, β-pinene, α-pinene and α-terpineol. The antioxidant activity of all essential oils was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), photochemiluminescence (PCL) quantitative assays, and DPPH and ABTS bioautographic profiles, with different results for each of them. Antimicrobial activity studies were carried out on three yeasts, six Gram positive and four Gram negative bacteria, by means of the disc diffusion method. The essential oil of H. coronarium showed the most relevant results on L. grayi, K. oxytoca and S. mutans, P. augustum and P. leticianum on S. mutans. An antibacterial bioautographic test for H. coronarium was also carried out and highlighted the potential activity of terpinen-4-ol and 1,8-cineole.

This study evaluates the antimicrobial and antifungal potential of the essential oil extracted from a species located in the Andes of Ecuador, Piper barbatum Kunth, known as “cordoncillo” or “allupa”, used by the Quichua people as an antibacterial plant for washing female genitalia in cases of infection. The most abundant molecules in the essential oil were: α- phellandrene (43.16%), limonene (7.04%); some oxygenated sesquiterpenes such as: trans-sesquisabinene hydrate (8.23%), elemol (7.21%) and others. The evaluation of antimicrobial activity showed activity in all the strains analyzed; however, those in which MIC values are considered to be very strong (less than 500 µg/mL) are: Staphylococcus aureus 264 µg/mL, Streptococcus mutans 132 µg/mL, Candida albicans 132 µg/mL and Candida tropicalis 264 µg/mL. Antimicrobial bioautography defines which molecules are responsible for the activity; thus, it was possible to establish the chromatographic regions of = 0.02 and Rf = 0.04, as those with active molecules. It was established that 4 hydroxylated sesquiterpene molecules are involved: elemol (7.21%), trans-sesquisabinene hydrate (8.23%), β–eudesmol (3.49%) and 10-epi-γ-eudesmol (1.07%); the last two being the most active. The aim of this manuscript is to analyze both the ancestral knowledge of the Quichua people of Ecuador, and the chemical-biodiversity of the Andean forest ecosystem, in order to provide new raw materials of pharmaceutical interest.

Secondary metabolites from plant organisms have always been excellent options for the pharmaceutical, cosmetic, and food industries. Essential oils are a type of metabolites found in vegetables, and their chemical composition is diverse; however, monoterpenes and sesquiterpenes are inside the most abundant molecules. These terpenes have a diverse chemical composition that range from a simple molecule with carbon and hydrogen to more complex molecules with oxygenated organic groups, such as alcohols, aldehydes, ketones, and ethers. Many of these molecules with 10 and 15 carbon atoms have an especially important biological activity, being important the antimicrobial, antifungal, antioxidant, anti-inflammatory, insecticide, analgesic, anticancer, cytotoxic, among others. Some of these substances are potentially toxic, and hence, they should be handled with caution, especially when they are pure. They are easily obtained by different methods, and their industrial value grows every year, with a market of several million dollars. This chapter seeks to provide a better understanding of this type of bioactive molecules, with an emphasis in those whose information is remarkable in the scientific literature and whose value for health and human well-being makes them extremely important.

The Amazonian region of Ecuador has an extremely rich vegetal biodiversity, and its inhabitants have proven to have a millennial ancestral knowledge of the therapeutic and medicinal use of these resources. This work aimed to evaluate the chemical composition and biological activity of the essential oil obtained from the medicinal plant Clinopodium brownei (Sw.) Kuntze, which is widely spread in tropical and subtropical America. This species is traditionally used for treating respiratory and digestive diseases and is also known for its analgesic properties. Most of the molecules detected on a non-polar column were ethyl cinnamate 21.4%, pulegone 20.76%, methyl cinnamate 16.68%, caryophyllene 8.17%, β-selinene 7.92% and menthone 7.51%, while those detected on a polar column were: pulegone 29.90%, ethyl cinnamate 18.75%, methyl cinnamate 13.82%, caryophyllene 10.0% and menthone 8.04%. The antioxidant activity by the assays, DPPH (2.2-diphenyl-1-picrylhydrazyl) and ABTS (2.2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)), shows the following values of 50% inhibition of oxidation, IC50 DPPH 1.77 mg/mL, IC50 ABTS 0.06 mg/mL, which, compared to the essential oil of Thymus vulgaris (natural positive control), turn out to be less active. Bioautography indicates that the molecules responsible for the antioxidant activity are derived from cinnamic acid: ethyl cinnamate and methyl cinnamate, and caryophyllene. The antimicrobial activity on the nine microorganisms evaluated shows bacterial growth inhibitory concentrations ranging from 13.6 mg/mL for Staphylococcus epidermidis ATCC 14990 to 3.1 mg/mL for Candida albicans ATCC 10231; the results are lower than those of the positive control. Bioautography assigns antimicrobial activity to caryophyllene. The results indicate a very interesting activity of the essential oil and several of its molecules, validating the traditional use and the importance of this medicinal plant from Ecuador.

Magnolia pugana (Iltis & A. Vazquez) A. Vázquez & Carvajal, an endemic Mexican species of the Magnoliaceae family, has received limited phytochemical and pharmacological attention. This study reports, for the first time, the chemical composition and in vitro bioactivities of essential oils (EOs) obtained from its leaves, flowers, and seeds. EOs were analyzed by gas chromatography–mass spectrometry (GC-MS) and flame ionization detection (GC-FID), revealing cyclocolorenone, a sesquiterpene, as the major compound (38–40%) across all plant parts. Antioxidant activity was evaluated using DPPH• and ABTS• radical scavenging assays, complemented by bioautographic thin-layer chromatography (TLC). Antibacterial activity was determined by minimum inhibitory concentration (MIC) against human pathogenic bacteria, while cytotoxicity was assessed in MCF-7 (breast) and HT-29 (colon) cancer cell lines. Seed and flower EOs exhibited the highest antioxidant activity, with IC₅₀ values of 21.5 mg/mL and 9.04 mg/mL, respectively. Strong antibacterial effects were observed against Gram-positive strains, particularly Staphylococcus epidermidis (MIC = 355.11 µg/mL) and S. aureus (MIC = 710.23 µg/mL). Leaf EO showed selective cytotoxicity toward MCF-7 cells (IC₅₀ = 27.25 µg/mL), while seed EO was most active against HT-29 cells (IC₅₀ = 54.01 µg/mL). These results suggest that M. pugana EOs, especially those from seeds, are a promising source of natural antioxidant, antimicrobial, and anticancer agents.

The present research evaluated the chemical composition as well as the antioxidant and antimicrobial properties of the essential oil from the bark of Ocotea quixos (Lam.) Kosterm. The major components of the essential oil were cinnamaldehyde <(E)-> (30.69%), methoxy cinnamaldehyde <(E)-o-> (16.29%), cinnamyl acetate <(E)-> (12.18%), and methyl cinnamate <(E)-> (5.72%). The antioxidant capacity showed to be superior to that of the essential oil of Tymus vulgaris. The results show low half maximal inhibitory concentration (IC50) values, which means that the essential oil has a high activity: 2,2-diphenyl-1-picrylhydrazyl (DPPH) IC50, 2.786 ± 0.150 mg mL−1; 2,2′-azino-di-(3-ethylbenzthiazoline sulfonic acid (ABTS) IC50, 0.240 ± 0.034 mg mL−1; and IC50 β-carotene test, 0.496 ± 0.017 mg mL−1. The essential oil was active with all the microorganisms evaluated, being very active against: Escherichia coli ATCC (American type culture collection) 25922, Staphylococcus aureus ATCC 29213, Listeria grayi ATCC 19120, M...