Spice plants have a great influence on world history. For centuries, different civilizations have used them to condiment the foods of kings and nobles and applied them as embalming preservatives, perfumes, cosmetics, and medicines in different regions of the world. In general, these plants have formed the basis of traditional medicine and some of their derived substances have been utilized to treat different human diseases. Essential oils (EOs) obtained from these plants have been also used as therapeutic agents and have shown supportive uses in remedial practices. The discovery and development of bioactive compounds from these natural products, based on their traditional uses, play an important role in developing the scientific evidence of their potential pharmaceutical, cosmetic, and food applications. In the present review, using recent studies, we exhibit a general overview of the main aspects related to the importance of spice plants widely used in traditional medicine: Cinnamomum zeylanicum (true cinnamon), Mentha piperita (peppermint), Ocimum basilicum (basil), Origanum vulgare (oregano), Piper nigrum (black pepper), Rosmarinus officinalis (rosemary), and Thymus vulgaris (thyme); and we discuss new findings of the bioactive compounds obtained from their EOs, their potential applications, as well as their molecular mechanisms of action, focusing on their antioxidant activity. We also exhibit the main in vitro methods applied to determine the antioxidant activities of these natural products.

Nanotechnology is a cutting-edge area with numerous industrial applications. Nanoparticles are structures that have dimensions ranging from 1 – 100 nm, which significantly exhibit different mechanical, optical, electrical, and chemical properties when compared with their larger counterparts. Synthetic routes that use natural sources, such as plant extracts, honey, and microorganisms, are environmentally friendly and low-cost methods that can be used to obtain nanoparticles. These methods of synthesis generate products that are more stable and less toxic than those obtained using conventional methods. Nanoparticles formed by titanium dioxide, zinc oxide, silver, gold, and copper, as well as cellulose nanocrystals, are among the nanostructures obtained by green synthesis that have shown interesting applications in several technological industries. Several analytical techniques have also been used to analyze the size, morphology, hydrodynamics, diameter, and chemical functional groups involved in the stabilization of the nanoparticles as well as to quantify and evaluate their formation. Despite their pharmaceutical, biotechnological, cosmetic, and food applications, studies have detected their harmful effects on human health and the environment, and thus, caution must be taken in uses involving living organisms. The present review aims to present an overview of the applications, the structural properties, and the green synthesis methods that are used to obtain nanoparticles, and special attention is given to those obtained from metal ions. The review also presents the analytical methods used to analyze, quantify, and characterize these nanostructures.

Background: Paullinia cupana Kunth, popularly known as guarana, a native Amazonian shrub cultivated by the Sateré-Mawé ethnic group, has been used in traditional medicine for various purposes, including stimulant and therapeutic actions, due to its chemical composition, which is rich in bioactive compounds. This study explored the reductive potential of guarana with nanobiotechnology and aimed to synthesize silver nanoparticles (AgNPs) using the aqueous extract of leaves collected during the dry and rainy seasons, assessing their biological and catalytic activities. Methods: The AgNPs were synthesized in a water bath at 70 °C for three hours and then characterized using techniques such as UV-Vis spectroscopy, DLS, zeta potential, MET, NTA, and EDX and had their effects on various biological systems assessed in vitro, as well as in catalytic tests aimed at indicating the probable influence of the time when the plant material was collected on the properties of the nanostructures. Results: The AgNPs had an average diameter between 39.33 and 126.2 nm, spherical morphology, absorption bands between 410 and 450 nm, and high colloidal stability over two years. The biological results showed antibacterial activity against all the species tested, as well as remarkable antioxidant action against DPPH and ABTS free radicals, in the same way as the aqueous leaf extracts of P. cupana, in addition to cytotoxic properties against cancerous (A431 and A549) and non-cancerous (HaCaT and HNTMC) cells. The AgNPs were active against promastigote forms of Leishmania (Leishmania) amazonensis while not affecting the viability of macrophages, and from the LC₅₀ and LC₉₀ values, the AgNPs were more effective than the metal salt solution in controlling Aedes aegypti larvae and pupae. We also reported that the catalytic degradation of the organic dyes methylene blue (MB) and methyl orange (MO) by AgNPs was over 90% after 40 or 14 min, respectively. Conclusions: Thus, our results support the potential of seasonal extracts of guarana leaves to produce AgNPs with diverse application possibilities for the health, industrial, and environmental sectors.

Milk is a very important food for human consumption, mainly due to its content of fat, protein, vitamins and minerals. However, the use of organochlorine pesticides (OCP) for decades has contaminated the soil, water and air, and thus has also contaminated the milk. In this sense, in the present work a review of scientific articles was carried out, between the years 2000 and 2018, related to the evaluation of the degree of contamination of different types of milk by OCPs in different regions of the world. As a result, it was observed that although OCPs have been banned for use in agriculture since the 1980s, these compounds or their metabolites have still been detected in many samples, and in some cases the levels were above the maximum allowed by the World Health Organization. In addition, most of the samples presented contamination, which makes them a great risk to human health due to their bioaccumulation.

This study proposes the preparation, characterization, and evaluation of the antimicrobial activity of silver nanoparticles (AgNPs). AgNPs were synthesized from the leaf extracts of plants from the Arecaceae family, which are abundant in the Amazon region. AgNPs were characterized using UV/Vis spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), dynamic light scattering (DLS), and their minimum inhibitory concentrations (MIC) against the bacteria Escherichia coli and Staphylococcus aureus. AgNPs presented maximum absorbance between 420 and 430 nm, the mean diameter obtained by DLS ranged from 130.43 to 352.93 nm and the polydispersity index (PdI) ranged from 0.523 to 0.689. The surface charge measured by the Zeta potential was negative and ranged from -17.2 to -26.97 mV. FTIR analysis suggests that the phenolic compounds and/or proteins in the chemical composition of the plants studied may have been responsible for the reduction of Ag+ ions and stabilization of AgNPs. The morphology of AgNPs observed was largely spherical and presented some agglomerates. Transmission electron microscopy analyses showed polydispersed AgNPs without the formation of large agglomerates. The synthesized AgNPs presented homogeneity and rapid bioreduction. The concentration of AgNPs required to eliminate microorganisms by up to 90% was lower for Gram-negative bacteria (2.75 μg mL-1) than for Gram-positive bacteria (21.75 μg mL-1). In addition, AgNPs synthesized from plant species that are native to the Amazon proved to be promising, since they showed excellent antimicrobial activity against microorganisms of clinical interest.