**1. Introduction**

The Amazonian biodiversity presents a great source of foods and medicinal plants rich in antioxidant compounds whose study and conscious exploration contribute to the region sustainable development [1, 2]. The plants have a great importance due to their medicinal and nutritional properties. About 70–90% of the world population prefers the use of medicinal plants or plant extracts to treat common diseases [3, 4]. Plants have been extensively studied in recent years for their antioxidant activity. The main classes of plant chemicals are phenolic compounds, tocopherols, carotenoids, and alkaloids. Among these compounds, phenolic compounds are the most important. They prevent or delay oxidative stress, acting as free radical scavengers (FRSs), and thus reduce the onset of different chronic diseases [5–8].

Antioxidants are a set of substances that can delay or inhibit oxidation reactions and act as a defense mechanism to neutralize the harmful effects of oxidation in biological systems and foods [6, 9, 10]. Oxidative stress is considered a state of imbalance where excessive amounts of reactive oxygen and nitrogen species (ROS/RNS, for example, superoxide anion, hydrogen peroxide, hydroxyl radical, peroxynitrite) exceed the capacity of endogenous antioxidants (uric acid, superoxide dismutase, catalase, glutathione peroxidase), leading to the oxidation of a biomacromolecule variety such as enzymes, proteins, DNA, and lipids. Exogenous antioxidants (phenolic compounds, carotenoids, tocopherols, and ascorbates) are consumed in the diet mainly of fruits, leaves, seeds, vegetables, and cereals, they have the function of increasing or protecting the antioxidant defense in biological systems and, therefore, they are important for endogenous oxidative stability [11–13].

It is conflicting that oxygen and nitrogen, considered essential for biological processes, are also cofactors for toxic and degenerative processes. In this sense, the antioxidant compounds act through different chemical mechanisms in order to minimize or maintain redox balance in vivo [9, 14]. There are several mechanisms by which oxidation can be inhibited. In general, the mechanisms involved include FRSs, ester bond enzymatic hydrolysis, transition metal ion sequestration, and enzyme-catalyzed peroxide reduction. The last three mechanisms mentioned do not cease reactive species action, but prevent the formation of molecules capable of promoting free radical chain reactions [15].

There is a growing interest in new sources of natural antioxidant compounds due to synthetic antioxidants such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ ) in the food industry being severely restricted, since they may show carcinogenic effects on living organisms [16–18]. In this sense, the scientific community and consumers are looking for new bioactive compounds of natural origin that can be used to develop new treatments against diseases. In addition, they may be employed in the food industry as functional food ingredients.

*Cissus sicyoides* L., which belongs to the Vitaceae family, is also known as vegetal insulin, anil-trepador, bejuco-caro, cipó-pucá, or puci. It is considered a plant from the Neotropical region and is usually found in the Amazon region [19, 20]. According to studies on *C. sicyoides* extract composition, the presence of bioactive compounds with high antioxidant activity as carotenoids and phenolic compounds (flavonoid, resveratrol, coumarins, and tannins) was found [21–23]. Therefore, it is a plant traditionally used by Brazilian popular medicine to treat rheumatism, epilepsy, stroke, abscesses, arthritis, and diabetes [23, 24].

*Rosmarinus officinalis* is an aromatic plant of the Lamiaceae family, native to the Mediterranean region. Today, it has been grown in many parts of the world and is known as rosemary [25, 26]. It has been recognized as one of the plants with great antioxidant activity. Among the most effective antioxidant constituents, cyclic diterpene diphenols, carnosic acid, rosmarinic acid, and carnosol have been identified. *R. officinalis* extracts have been used in the treatment and/or prevention of diseases such as cancer, Alzheimer's disease, urinary and gastrointestinal infections, diabetes, ischemia, and atherosclerosis [17, 25–32]. *R. officinalis* extract has been commercially exploited as a natural antioxidant [5, 16].

Supercritical fluid extraction (SFE) has already been studied to obtain bioactive compounds from natural sources. Salazar et al. and Carvalho et al. showed that the application of SFE technology is successful in obtaining extracts from *C. sicyoides* and *R. officinalis*, respectively, with high antioxidant capacity [24, 33]. SFE is based on the use of solvents with temperatures and pressures above their critical points, which have a high solvency power. One of the most commonly used solvents in SFE is carbon dioxide (CO2) since its critical points are moderate, nontoxic,

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**Figure 1.**

*Antioxidant and Biological Activity of* Cissus sicyoides and Rosmarinus officinalis *Extracts*

non-flammable, affordable, chemically inert, and apolar and has an ideal behavior for thermosensitive compound extraction. In SFE it is possible to obtain totally solvent-free extracts without compound thermal degradation due to the low operat-

Supercritical CO2 (Sc-CO2) has a limitation in dissolving polar molecules. However, this disadvantage can be solved by polar solvent addition, called modifiers or cosolvents, which modify the supercritical fluid polarity and, consequently, improve polar fraction extraction rich in bioactive substances, such as phenolic compounds related to high antioxidant activity [37, 38]. The aim of this chapter is to describe the antioxidant and biological activity of *Cissus sicyoides* and *Rosmarinus officinalis* leaf extracts that represent an important natural source of antioxidants. In addition to providing an overview of the SFE that is currently presented as a modern and environmentally safe extraction technology for antioxidant compound extraction.

*Cissus sicyoides* L. or *Cissus verticillata* L., which belongs to the Vitaceae family, is also known as vegetal insulin, cipó-pucá, or puci. It is considered a plant of the Neotropical region and is usually found in the Amazon region. It is a climbing plant, which can reach up to 6 m in length, and presents fleshy articulated branch, alternating leaf of ovate format, pale or yellowish-green flowers, and round fruit, with

The bioactive compounds present in the leaf and stem are represented by carotenoids (α-carotene and β-carotene) [39] and phenolic compounds such as

*Description of C. sicyoides parts and the main chemical structure of the antioxidant compounds.*

variations of color from violet to black (**Figure 1**) [19, 20].

*DOI: http://dx.doi.org/10.5772/intechopen.83733*

ing temperatures applied [34–37].

**2.** *Cissus sicyoides*

**2.1 Botanical description**

**2.2 Chemical composition**

*Antioxidant and Biological Activity of* Cissus sicyoides and Rosmarinus officinalis *Extracts DOI: http://dx.doi.org/10.5772/intechopen.83733*

non-flammable, affordable, chemically inert, and apolar and has an ideal behavior for thermosensitive compound extraction. In SFE it is possible to obtain totally solvent-free extracts without compound thermal degradation due to the low operating temperatures applied [34–37].

Supercritical CO2 (Sc-CO2) has a limitation in dissolving polar molecules. However, this disadvantage can be solved by polar solvent addition, called modifiers or cosolvents, which modify the supercritical fluid polarity and, consequently, improve polar fraction extraction rich in bioactive substances, such as phenolic compounds related to high antioxidant activity [37, 38]. The aim of this chapter is to describe the antioxidant and biological activity of *Cissus sicyoides* and *Rosmarinus officinalis* leaf extracts that represent an important natural source of antioxidants. In addition to providing an overview of the SFE that is currently presented as a modern and environmentally safe extraction technology for antioxidant compound extraction.
