COVID-19 pandemic sheds a new research spotlight on antiviral potential of essential oils - A bibliometric study

Background

Essential oils are thought as potential therapies in managing coronavirus disease 2019 (COVID-19). Many researchers have put their efforts to tackle the pandemic by exploring antiviral candidates which consequently changes the research landscape. Herein, we aimed to assess the effect of COVID-19 pandemic toward the landscape of essential oil research.

Methods

This study employed bibliometric analysis based on the metadata of published literature indexed in the Scopus database. The search was performed on December 15th, 2022 by using keyword 'essential oil' and its synonyms. We grouped the data based on publication year; pre-COVID-19 (2014-2019) and during COVID-19 (2020-2024, some studies have been published earlier). Further, we separated the COVID-19-focused research from COVID-19 (2020-2024) by introducing a new keyword 'COVID-19' during the search. All metadata were processed using VoSviewer and Biblioshiny for network visualization analysis. Selections of frequently occurring keywords, clusters of keyword co-occurrence, and the list of most impactful papers were performed by two independent reviewers.

Results

Metadata from a total of 35,262 publications were included for bibliometric analysis, comprised of three groups of datasets namely pre-COVID-19 (n = 18,670), COVID-19 (n = 16,592), and COVID-19-focused (n = 281). Five research topics clusters were found from pre-COVID-19 dataset, eight - from COVID-19 dataset, and nine - from COVID-19-focused dataset. COVID-19 cluster containing the keyword 'antiviral' emerged in the COVID-19 dataset, whereas none of the previous research topic clusters contained the keyword 'antiviral'. Antiviral, angiotensin-converting enzyme 2 (ACE2) inhibitory, and anti-inflammation activities were among the top occurring keywords in studies covering both essential oil and COVID-19. Studies on essential oil used for managing COVID-19 were most reported by authors from the United States (documents = 37, citations = 405), Australia (documents = 16, citations = 115) and Italy (documents = 23, citations = 366).

Conclusion

A significant increase was found during COVID-19 pandemic for publications covering essential oil themes, but only a small portion was occupied by COVID-19 research. The COVID-19 pandemic does not alter the ongoing progress of essential oil research but rather offers a new spotlight on the antiviral potential of essential oils. Hence, the COVID-19 pandemic has provided an opportunity to investigate deeper the antiviral potential of essential oils.

A Multidimensional Review of Pimpinella anisum and Recommendation for Future Research to Face Adverse Climatic Conditions

Anise, or Pimpinella anisum, has a long history of usage in traditional and alternative medicine, as well as in the pharmaceutical sector. The species is native to Southwest Asia, the Middle East, and the Mediterranean region. The current studies have revealed that wild and cultivated P. anisum are rich in bioactive compounds, such as phenols, tannins, carotenoids, and fatty acids. Different parts of P. anisum plant are used treatment of diseases, the treatment of pathogens for antiviral, antibacterial, and antifungal purposes, and cosmetics. In this paper, we reviewed the current knowledge on geographical distribution, cultivation, chemical compounds, extraction methods, and agronomic and medicinal uses of Pimpinella anisum. Equally, we suggested guidelines for future research to fill the gap in less investigated issues. Data for this paper was gathered via electronic literature search on Google, Google Scholar, and databases counting, Science Direct, Scopus, Springer, PubMed, and Hindawi, from 1930 to 2022. Analyzed data show that Pimpinella anisum is currently recorded from Portugal on the Atlantic Ocean in the west to China in the East. With new extraction methods, such as Ultrasound-Assisted Extraction, scientists have explored the higher quantities of polyphenols, flavonoids, and antioxidants, and revealed new constituents such as trans-anethole and estragole found in essential oil fruits by gas chromatography-mass spectrometry (GC–MS). These compounds showed significant therapeutic benefits against diseases, pathogens, and cosmetic roles. However, with the current impacts of climate change on natural vegetation cover, more investigations are needed to understand how these affect the geographical distribution, metabolic aspects, and chemical properties of Pimpinella anisum. These are suggested to increase the value of the species and ensure its conservation.

Antiviral Potential of Traditional Unani Medicine with Special Emphasis on Dengue: A Review

Dengue fever has become a major public health concern. It is usually related to intravascular leaking, bleeding disorders, and thrombocytopenia and is recognized as a potent threat to humans. The scarcity of anti-dengue medication or vaccine for such a serious disease leads to an upsurge in the usage of traditional medicines for its proper management. India has diverse biodiversity and a long history of using plant-based remedies. Several medicinal plant extracts have been studied for producing anti-dengue viral activity. AYUSH traditional systems provide a plethora of plants that have been reported to be useful in the treatment of fever. Single and compound plant- based formulations in natural form have been used in Unani holistic approaches. This review serves as a new approach to illustrate the most recent evidence regarding the antiviral activity of various plants by providing scientific proof and also to validate the traditional formulations as effective treatments in dengue fever for global acceptance.

Antiviral Activity of Selected Essential Oils against Cucumber Mosaic Virus

The aim of the study was to assess the antiviral activity of selected essential oils (EOs) against Cucumber mosaic virus (CMV), both in vitro and in vivo. The observations were made using Chenopodium quinoa as a local host. The EOs were obtained from Greek oregano, thyme, and costmary. Their chemical composition was determined using GC/FID followed by GC/MS. The dominant compound in oregano EO was carvacrol (59.41%), in thyme EO-thymol (59.34%), and in costmary EO-β-thujone (90.60%). Among the analysed EOs, thyme EO exhibited the most promising effects against CMV. However, its activity was influenced by the time of application. In an in vivo experiment, thyme EO showed protective (pre-inoculation) rather than curative (post-inoculation) activity.

Foeniculum vulgare essential oil ameliorates acetic acid-induced colitis in rats through the inhibition of NF-kB pathway

AIM

The aim of the present study is to investigate the protective effects of Foeniculum vulgare essential oil on intestinal inflammation through the inhibition of NF-kB pathway in acetic acid-induced rat colitis.

METHODS

Acute colitis was induced by intra-rectal administration of 2 mL of diluted acetic acid (4%) solution. Two hours after the induction of colitis, 0.2% tween 80 in normal saline, dexamethasone (2 mg/kg) and F. vulgare essential oil (100, 200, 400 mg/kg) were administered to the animals by oral gavage and continued for 5 consecutive days. Assessment of macroscopic and microscopic lesions was done. MPO activity was evaluated by biochemical method. Furthermore, TNF-α activity was detected by immunohistochemistry (IHC) and the expression level of p-NF-kB p65 protein was measured by western blot analysis.

RESULTS

Dexamethasone and F. vulgare essential oil (200, 400 mg/kg) reduced the macroscopic and microscopic lesions compared to the acetic acid group (p < 0.01, p < 0.001). In addition, these agents decreased the activity of MPO (p < 0.01, p < 0.001) and the expression of TNF-α positive cells (p < 0.05, p < 0.01, p < 0.001) in the colon tissue compared to acetic acid group. Furthermore, they inhibited acetic acid-induced expression of p-NF-kB p65 protein (p < 0.05, p < 0.001).

CONCLUSION

It is proposed that the anti-inflammatory activity of F. vulgare essential oil on acetic acid-induced colitis in rats may involve the inhibition of NF-kB pathway.

The Effect of Hydro-Alcoholic Extract of Foeniculum vulgare Mill on Leukocytes and Hematological Tests in Male Rats

BACKGROUND

Medicinal plants have a long history in treating blood disorders, which is one of the most common problems in today's advanced world. Fennel (Foeniculum vulgare) is a medicinal plant with a high content of polyphenols and has antioxidant and immunomodulatory properties.

OBJECTIVES

The aim of this study was to evaluate the effect of hydro-alcoholic extract of fennel on some hematological indices in male rats.

MATERIALS AND METHODS

In this experimental study, thirty male Wistar rats were divided into six groups (five rats in each group). The first group (control) did not receive any dose; the second group (sham) received 1 mL normal saline (extraction solvent); and the experimental groups 1, 2, 3 and 4 respectively received 1 mL hydro alcoholic extract of fennel in four doses of 250, 500, 750 and 1000 mg/kg of body weight every 48 hours for 30 days by gavage. One day after the last gavage following induction of anesthesia and taking blood from the heart of rats, measurement of red and white blood cells, hemoglobin, hematocrit and tests of bleeding and coagulation time (CT) were performed. The data was analyzed by one-way ANOVA test using SPSS15 software.

RESULTS

Fennel increased mean RBC (7.54 ± 0.53 × 106) and WBC (5.89 ± 0.78 × 103) values, especially at a dose of 250 mg/mL and CT (2.45 ± 0.20) at a dose of 500mg/mL compared to the control group (P < 0.05).

CONCLUSIONS

Fennel increased red and white blood cells probably due to the presence of polyphenols and antioxidant activity of fennel and reduced negative effects of free radicals on blood cells.

Review of Pharmacological Properties and Chemical Constituents of Pimpinella anisum

Pimpinella anisum (anise), belonging to Umbelliferae family, is an aromatic plant which has been used In Iranian traditional medicine (especially its fruits) as carminative, aromatic, disinfectant, and galactagogue. Because the wide traditional usage of Pimpinella anisum for treatment of diseases, in this review published scientific reports about the composition and pharmacological properties of this plant were collected with electronic literature search of GoogleScholar, PubMed, Sciencedirect, Scopus, and SID from 1970 to 2011. So far, different studies were performed on aniseeds and various properties such as antimicrobial, antifungal, antiviral, antioxidant, muscle relaxant, analgesic and anticonvulsant activity as well as different effects on gastrointestinal system have been reported of aniseeds. It can also reduce morphine dependence and has beneficial effects on dysmenorrhea and menopausal hot flashes in women. In diabetic patients, aniseeds showed hypoglycemic and hypolipidemic effect and reduce lipid peroxidation. The most important compounds of aniseeds essential oil were trans-anetole, estragole, γ-hymachalen, para-anisaldehyde and methyl cavicol. Due to broad spectrum of pharmacological effects, and very few clinical studies of Pimpinella anisum, more clinical trials are recommended to evaluate the beneficial effects of this plant in human models and synthesis of new drugs from the active ingredients of this plant in future.

Chemomodulatory action of Foeniculum vulgare (Fennel) on skin and forestomach papillomagenesis, enzymes associated with xenobiotic metabolism and antioxidant status in murine model system

The chemopreventive effect of different doses of test diet of Foeniculum vulgare Mill (Fennel) seeds was examined on DMBA-induced skin and B(a)P-induced forestomach papillomagenesis in Swiss albino mice. To the best of our knowledge, this is the first report of Fennel seeds exhibiting a significant reduction in the skin and the forestomach tumor incidence and tumor multiplicity as compared to the control group. Further, biochemical assays showed a significant increase in the content/activities of phase I enzymes especially in the case of 6% test diet. A concomitant increase in the activities of the phase II enzymes were observed with all the doses of test diet under study. A significant enhancement in the activities of antioxidant enzymes were observed especially at 4% and 6% test diets of Fennel. Glyoxalase I activity and the content of reduced glutathione were significantly elevated. Expectedly, the levels of peroxidative damage along with lactate dehydrogenase activity, exhibited a significant reduction at all three doses of test diets. These findings were indicative of chemopreventive potential of Fennel against carcinogenesis.