Carvacrol has a high therapeutic potential, with in vitro studies showing promising results in different cellular models using a variety of methodological designs. Therefore, the objective of this study was to conduct a systematic review to analyze the pharmacological effects of carvacrol in in vitro studies. A comprehensive search of the literature was made using four databases: Science Direct, Scopus, MEDLINE-PubMed, and Web of Science using different combinations of the following keywords: carvacrol, drug therapy, therapeutic uses, in vitro study. The search of the databases was for studies conducted in the period up to and including September 2016. A total of 3,269 studies were initially identified, with only 31 meeting the inclusion criteria. The included studies contained a variety of in vitro models able to determine the properties of Carvacrol. The following properties of Carvacrol were identified: antimicrobial (7 studies), bactericidal (4), bactericidal and antifungal (1), antiinflammatory (4), anticancer (4), mutagenic (4), antioxidant (3), antifungal (3), antidepressant (1), as a modulator of nerve impulses (1) and an immunological modulator (1). The In vitro studies with Carvacrol included in this review showed a diversity of models and confirmed the therapeutic potential of this product in relation to several diseases.

Carvacrol is a monoterpene present in the essential oil of a number of plants and has been widely used in traditional medicine because it is considered to have a range of therapeutic effects including in relation to respiratory disease. To conduct a systematic review and meta‐analysis to assess the anti‐inflammatory and antioxidant activities of carvacrol when used in the treatment of respiratory disorders. A comprehensive literature search using Scopus, MEDLINE‐PubMed, Cochrane and Web of Science was undertaken. Papers related to the anti‐inflammatory or antioxidant properties of carvacrol in the treatment of an injury in the respiratory system in in vivo studies and published in the period up to and including August 2019. A total of 152 studies were initially identified, with only 17 meeting the inclusion criteria. Five of the studies were performed in humans, and 12 were performed in rodents. Among the 17 studies included in the systematic review, we performed the meta‐analysis with nine of the studies with animals. Carvacrol had a positive effect on the reduction of interleukin (IL)‐1β, IL‐4, IL‐8 and malondialdehyde (MDA); however, the analysis indicated that carvacrol had no effect on IL‐6 and tumor necrosis factor alpha (TNF‐α), probably due to the methodological quality of the studies and their heterogeneity. Current evidence supports the antioxidant and anti‐inflammatory effects of carvacrol, but its relationship with the reduction of some inflammatory mediators in animals with lung injury needs further elucidation.

Introduction: The pulmonary inflammatory response results from exposure to injurious factors and is associated with oxidative stress, which intensifies the pathological reaction. In this context, limonene, a monoterpene found in citrus fruits, can be a therapeutic alternative for the treatment of this pathology, as it presents known anti-inflammatory and antioxidant actions. Objective: The purpose of this article is to provide an overview of the anti-inflammatory activity of limonene and its capacity to prevent and control respiratory system injuries. Search strategy: A comprehensive literature search of the Cochrane, Scopus, MEDLINE-PubMed, Web of Science, and Lilacs databases was performed using the keywords: "limonene", “lung”, “pulmonary”, “airway”, “trachea”, “lung injury”, "respiratory system", “respiratory tract diseases”. Search strategy: A comprehensive literature search of the Cochrane, Scopus, MEDLINE-PubMed, Web of Science, and Lilacs databases was performed using the keywords: "limonene", “lung”, “pulmonary”, “airway”, “trachea”, “lung injury”, "respiratory system", “respiratory tract diseases”. Selection criteria: Studies on the use of limonene in disorders of the respiratory system, published until August 2019, were included. Those that did not use limonene alone or treated lesions in different systems other than the respiratory system, without targeting its anti-inflammatory action were excluded. In addition, review articles, meta-analyses, abstracts, conference papers, editorials/letters and case reports were also excluded. Results: Of the 561 articles found, 64 were in the Cochrane database, 235 in Scopus, 99 in Web of science, 150 in PubMed and 13 in Lilacs. After completing the systematic steps, 25 articles were selected for full reading, after which 7 papers remained in the review. An article was added after a manual literature search, resulting in a total of 8 papers. There was a high level of agreement on inclusion/exclusion among the researchers who examined the papers (Kappa index > 88%). Conclusion: Limonene has effective anti-inflammatory activity in both preventing and controlling respiratory system injuries.

Background: Cancer is a complex, multifactorial disease, and a major public health problem, as it is a leading cause of morbidity and mortality worldwide. Although treatments have significantly improved, there is a still a search for more effective drugs. One source for these are natural products (NPs). One NP that has shown anticancer activity is Limonene. However, the mechanisms of limonene's antiproliferative, anticancer and antineoplastic activity are not fully understood. Objective: The objective of this study is, therefore, to undertake a systematic review and meta-analysis of the literature on this subject. Methods: A comprehensive literature search was performed using the Scopus, MEDLINE-PubMed, Web of Science, and Science Direct databases using the keywords: "limonene", “cancer”, “neoplasm”, “tumor”. The inclusion criteria were: in vivo and in vitro studies on the use of limonene in cancer published in English, Portuguese and Spanish until December 2019. Review articles, meta-analyses, abstracts, conference papers, editorials/letters and case reports were excluded. Results: The search identified 3568 articles. Of which 126 were selected for full reading with 11 papers meeting the review criteria. Six more papers were added from the references of the initial 11 texts, giving a total of 17 papers. There was a high level of agreement on inclusion/exclusion (Kappa index > 80%). Risk of bias I the texts was shown to be high. Conclusion: The meta-analysis suggests that limonene acts mainly on tumor regression induced apoptosis, and is a promising natural product for use in the treatment of several types of cancer.

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