INTRODUCTION
Chronic wounds are characterized by a deviation in the normal healing process and typically are associated with systemic impairment or diseases. These wounds are debilitating in their persistence and can lead to functional disability and dependence. Patients with chronic wounds may have mild, moderate, or severe depression.1 Considering this information and the economic and social costs for treatment, chronic wounds represent a serious health problem.
Pressure injuries (PIs) are one such chronic wound and can affect all layers of the body, from the outermost layers of skin to the muscles, cartilage, and bone. In Brazil, it is estimated that PIs, on average, occur in 36.56% of patients in ICUs, in 42.60% of internal medicine patients, and in 39.05% of surgical patients. Pressure injuries have significant economic impact, because it affects millions of patients, which makes this condition a major public health problem to be studied.2 Despite this, there are still no real cost data regarding treatment of this condition in Brazil.
There are more than 2,000 products on market to treat wounds, which makes choosing suitable products difficult.3 Current therapeutic agents can present problems concerning adherence to treatment, mainly because of adverse effects. Medicinal plants have been used to treat illness since ancient times, and some are well known for their abilities to promote wound healing and prevent infection without serious adverse effects. Therefore, herbal therapy may be an attractive alternative strategy for treatment of wounds.
In Brazil, pharmaceutical products based on essential fatty acids (EFAs), derived from vegetable oils, are widely available. These pharmaceutical products may contain one or more EFAs (linoleic and α-linoleic acids), as well as one or more vegetable oils, such as sunflower, calendula, or olive oil. Other vegetable fats rich in EFAs such as shea butter, for example, have demonstrated the ability to close and heal wounds.4
Fatty acids are very important to the formation and maintenance of cell membranes within the stratum corneum, the layer of the skin that provides a barrier to the environment and regulates permeability.4,5 Fatty acids also have lubricant, emollient, and anti-inflammatory properties, which help to restore the natural oils of the skin and protect it from environmental damage.6 Pharmaceutical products made with EFAs from vegetable oils, marketed in Brazil, sometimes contain other components such as vitamin E (tocopherol), which has antioxidant activity; vitamin A (retinoic acid), which can promote healing and epithelialization;7 lanoline and soy lecithin, which promote hydration and aid cicatricial processes of the skin;8,9 and medium-chain triglycerides (MCTs) such as capric and caprylic acids.
The MCTs are a class of lipids in which three saturated fatty acids are bound to a glycerol backbone. What distinguishes MCTs from other triglycerides is that each fatty acid molecule has between 6 and 12 carbons on its chain. These MCTs can treat PIs, help form a protective barrier on the skin, and prevent maceration. Besides being important in inflammatory process, MCTs promote the regeneration of cells and tissues, which improves immune response and wound healing via angiogenesis and epithelization.9,10
In recent years, there has been a growing trend toward the use of natural raw materials in pharmaceuticals and cosmetics. This has caused great interest in oils extracted from native plants of the Amazon forest, promoting a rapid and significant expansion of the national and international markets for these oils. This study aimed to evaluate the fatty acid composition of 21 vegetable oils marketed in Brazil and compare their composition with a commercial lotion used for wound healing to examine potential natural alternatives for wound treatment.
MATERIALS AND METHODS
Researchers analyzed a total of 21 commercial vegetable oils purchased in a Brazilian market as follows: andiroba (Carapa guianensis Aubl.), avocado (Persea americana Mill.), babassu (Attalea speciosa Mart. ex Spreng.), canola (Brassica napus L.), castor (Ricinus communis L.), coconut (Cocos nucifera L.), copaiba (Copaifera langsdorffii Desf.), corn (Zea mays L.), cottonseed (Gossypium hirsutum L.), grapeseed (Vitis vinifera L.), licuri or ouricuri (Syagrus coronata [Martius] Beccari), linseed (Linum usitatissimum L.), olive (Olea europaea L.), palm (Elaeis guineensis Jacq.), passion fruit (Passiflora edulis Sims.), pequi (Caryocar brasiliense Cambess.), pracaxi (Pentaclethra macroloba [Willd] Kuntze), soybean (Glycine max [L.] Merr.), sunflower (Helianthus annuus L.), and two mixed oils (soybean oil mixed with olive oil, and sunflower oil mixed with corn and canola oil). Dersani Original (Saniplan, Rio de Janeiro, Brazil) is a commercial lotion that was used as a reference product.
Basic transesterification was performed by reacting samples of 10 mg of each vegetable oil with 2.5 mL of 1.0 mol/L CH3ONa. Samples were placed in a water bath for 30 minutes at 70° C, and then allowed to stand for approximately 3 hours. Next, a hexane solution (1.0 mL) in water (1.5 mL) was added to the samples. After this, all samples were vortexed for 1 minute; then, the apolar phase (hexane) was withdrawn with the aid of an automatic pipette, and the polar phase was placed in a new hermetically sealed tube. This extraction process was performed in triplicate.
After this step, 1.0 mL of each sample was placed in vials and taken for gas chromatography-mass spectrometry and flame ionization detector analysis. Samples were injected twice. The gas chromatograph-mass spectrometer was a Shimadzu Model QP-2010; parameters included the following: column: ZB-WAX (30 m × 0.25 mm × 0.25 μm), split: 1:30, injection temperature: 240° C, column flow: 1.40 mL/min-1, carrier gas: helium. The oven temperature program was 50° C for 3 minutes and then 200° C for 8 minutes at a rate of 12° C/min-1 and then 240° C for 10 minutes at a rate of 5° C/min-1 with a total running time of 41.5 minutes. The solvent cut time was 3 minutes, the ion source temperature was 250° C, the ionization mode was electron ionization, and voltage was set to 70 V, scanning 35 to 500 m/z. Quantifications were expressed in mean percentage with SD.
RESULTS
Twelve fatty acids were identified in the commercial lotion (reference product). The Figure shows chromatograms of the identified fatty acids, and Table 1 shows their retention times. The reference product’s datasheet reports that the lotion’s composition includes triglycerides of capric and caprylic acids, clarified sunflower oil, lecithin, retinol palmitate, tocopherol acetate, and alpha-tocopherol,11 but it does not provide quantities. The main fatty acids found in the reference product were capric acid (18.8% ± 0.8%), caprylic acid (17.4% ± 0.4%), palmitic acid (3.8% ± 0.0%), stearic acid (2.7% ± 0.0%), oleic acid (27.5% ± 0.5%), and linolenic acid (28.1% ± 0.5%).
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Figure: CHROMATOGRAM OF THE FATTY ACIDS IN THE REFERENCE PRODUCT
Table 1.: RETENTION TIMES OF FATTY ACIDS FOUND IN THE REFERENCE PRODUCT
Table 2 lists the 11 most abundant fatty acids found in the analyzed oils. There are saturated fatty acids between C8:0 to C18:0; monounsaturated fatty acids C16:1, C18:1, and C18:1OH; and polyunsaturated fatty acids C18:2 and C18:3. The most abundant fatty acids found were caprylic acid (10.45% ± 0.07%), capric acid (5.8% ± 0.75%), lauric acid (45.63% ± 0.93%), and myristic acid (16.33% ± 2.23%). These fatty acids are all present in coconut and licuri oils. The presence of caprylic acid in babassu oil was not detected.
Table 2.: THE MOST ABUNDANT FATTY ACIDS FOUND IN ANALYZED OILS, %
The omega 9 oleic acid (52.94% ± 12.54%) is more abundant in andiroba (57%), avocado (51.7%), canola (65.9%), copaiba (42.7%), olive (75.8%), palm (42.9%), pequi (46.7%), and pracaxi (40.8%) oils. The omega 6 linoleic acid (57.09% ± 8.47%) is present in corn, cottonseed, grape seed, copaiba, passion fruit, soybean, and sunflower oils. It is also present in mixed oils (soybean and olive oil, 48.5%; sunflower with corn and canola oil, 53.2%). The omega 3 linolenic acid (46.55%) is present in linseed oil.
DISCUSSION
Most Brazilian plants from the Amazon river basin and Cerrado (Brazilian savanna) used in this study have medicinal properties, as demonstrated in biologic or ethnopharmacologic studies discussed here.
Licuri, also known as ouricuri, is a palm tree fruit commonly found in the semiarid Cerrado. Its high concentration of caprylic, capric, and lauric acids provides excellent spreadability and skin penetration.12 This oil has a low melting point (~30° C), so despite its solid appearance, it melts as soon as it comes into contact with human skin. It also has low acidity and high stability. Medium-chain length fatty acids such as lauric acid (C12:0) derived from babassu, coconut, and licuri oils are excellent surfactants that are extensively used in the production of soaps and detergents.13,14 The market for lauric acid alone is estimated to be worth more than US $1.4 billion annually.15 These results show that the composition of licuri oil is very similar to that of coconut oil, and licuri oil is significantly cheaper than coconut oil.
Monounsaturated fatty acids include oleic acid, an omega 9 fatty acid, which can be synthesized by all mammals, including humans, and thus represent important EFAs to be considered for drug formulations for use in wound healing.16 Both omega 3 and 6 essential oils have been shown to have properties that enhance wound closure and improve healing in several wound models.17–20
Copaiba is a characteristic Amazonian plant popularly used in Brazil for therapeutic purposes;21 its composition includes palmitic (11.9%), stearic (4.6%), oleic (42.7%), and linoleic (32.8%) acids.
The pequi oil is a kind of edible oil extracted from pequi seeds (Caryocar brasiliense), which grow abundantly in Brazil. Pequi oil is used for culinary, cosmetic, and medicinal purposes, and it can help heal cracked skin, psoriasis, and eczema.22 Many fatty acids were found in pequi oil, such as palmitic (36.3%), stearic (2.2%), oleic (46.7%), linoleic (10.7%), and linolenic (2.3%) acids.22 Pequi oil also contains vitamin E, vitamin A, and several antioxidants such as quercetin, gallic acid, quercetin 3-O-arabinose, and quinic acid. Its main carotenoids are violaxanthin, lutein, and zeaxanthin, with smaller amounts of β-cryptoxanthin, β-carotene, and neoxanthin.23 Sá24 studied the effect of pequi oil on PI healing and found better results when compared with Dersani.
Andiroba (Carapa guianensis) is used by indigenous Amazonians, particularly the Caboclos, to treat coughs, convulsions, skin diseases, arthritis, rheumatism, ear infections, wounds, and bruises, and as an insect repellent. The andiroba oil is a rich source of EFAs, including oleic, palmitic, myristic, and linoleic acids, and contains no lipids (triterpenes, tannins, or alkaloids). Andiroba oil has been shown to be effective in the treatment of actinic dermatitis and PIs, among other uses.25
Pracaxi oil (Pentaclethra macroloba) is used by several indigenous Amazonian communities for health applications such as treating ulcers and bacterial infections.26,27 Pracaxi oil contains high amounts of oleic, linoleic, and behenic acids, which are frequently used in the cosmetic industry26 because of their ability to keep skin moist. Studies have found different concentrations of behenic acid in pracaxi oil, from 5%,28 16.1%,26 to 19.67%.29 The concentration of behenic acid found in pracaxi oil in this study was 13.3%. These variations may occur naturally among plant varieties and could depend on climate and soil conditions. Pracaxi oil is an excellent choice for wound healing because of its lipids, which are a vital component of cell membranes and the epidermis; lipids can also protect the skin by preventing dehydration.30
Castor oil is obtained by pressing the seeds of the castor plant (Ricinus communis). Castor oil contains ricinoleic (84%), oleic (5.5%), linoleic (6.4%), and α-linolenic acids (6.5%). There is no other commercially produced vegetable oil that has these components, although plants of the Lesquerella genus also produce ricinoleic acid. Lesquerella species were proposed as a valuable source of ricinoleic acid (up to 70% concentrations in the oil) but also of lesquerolic acid, the C20 homolog of ricinoleic acid (14-hydroxy-11-eicosenoic acid).31 One of the most studied species is Physaria fendleri, formerly Lesquerella fendleri, or Brassicaceae. This plant corresponds to a new crop of industrial oil seeds produced in the southwestern region of the US, which has similar uses to castor oil.31
Because castor oil is composed of 80% to 90% ricinoleic acid, it has a high viscosity and alcohol solubility at low temperatures. It can be used as a raw material for biodiesel, but almost all of the castor oil produced in the world is used by the chemical industry for manufacturing products with a higher market value, such as for the antiseptic Ricinus Assept, a product containing 10% castor oil indicated for wound treatment in veterinary care.32
The Supplemental Table provided at the end of the article presents several studies that show vegetable oils, fatty acids, and commercial product potential to promote improvement in closure and treatment of wounds using different wound models.
In recent years, there has been a trend toward using natural raw materials in pharmaceuticals and cosmetics. This caused a rush to extract and study the oils from native Amazonian plants, leading to a quick and significant expansion of the national and international markets for these products. The Brazilian National Agency of Health Surveillance (Anvisa) provides data on registered medicines, cosmetics, foods, sanitizers, and healthcare products.33 Disposable health products for wound treatment made from EFA are registered at Anvisa, including health products and cosmetics (Tables 3 and 4). Currently, there is no EFA-based product registered as a medicine. Some articles and websites mention other vegetable oil-based products for treatment of wounds, for example, HIG-MED, which includes castor oil.34,35
Table 3.: COMMERCIAL HEALTH PRODUCTS THAT INCLUDE STUDIED OILS
Table 4.: COMMERCIAL COSMETICS THAT INCLUDE STUDIED OILS
New products based on these EFAs may be useful in clinical practice, especially considering some of these oils have already been tested in treating wounds and/or PIs. Data suggest that it may be possible to obtain a product by mixing two or more natural oils without adding any industrially processed components.33,36,37
CONCLUSIONS
Many of the oils included in this study have a similar fatty acid profile to the reference commercial lotion, which would suggest that these oils could be an alternative, natural source of fatty acids for wound care applications. Licuri and coconut oils may be a good source of caprylic and capric acids, and copaiba, corn, sunflower, soybean, and some combinations of these may be a good source of oleic and linoleic acids.
Most of these vegetable oils are products of tropical climates, where these plants are abundant and easy to cultivate, suggesting a promising economic potential for these plants. These results would support the development of a new product using a balanced composition of fatty acids from natural sources as an alternative method for the treatment of wounds. Additional study is warranted.
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