Essential oils are potential therapeutics for coronavirus disease 2019 (COVID-19), in which some of the volatile compounds of essential oils have been well known for their broad antiviral activities. These therapeutic candidates have been shown to regulate the excessive secretion of pro-inflammatory cytokines, which underlies the pathogenesis of severe COVID-19. We aimed to identify molecular targets of essential oils in disrupting the cell entry and replication of SARS-CoV-2, hence being active as antivirals. Literature searches were performed on PubMed, Scopus, Scillit, and CaPlus/SciFinder (7 December 2022) with a truncated title implying the anti-SARS-CoV-2 activity of essential oil. Data were collected from the eligible studies and described narratively. Quality appraisal was performed on the included studies. A total of eight studies were included in this review; four of which used enzyme inhibition assay, one—pseudo-SARS-CoV-2 culture; two—whole SARS-CoV-2 culture; and one—ACE2-expressing cancer cells. Essential oils may prevent the SARS-CoV-2 infection by targeting its receptors on the cells (ACE2 and TMPRSS2). Menthol, 1,8-cineole, and camphor are among the volatile compounds which serve as potential ACE2 blockers. β-caryophyllene may selectively target the SARS-CoV-2 spike protein and inhibit viral entry. Other interactions with SARS-CoV-2 proteases and RdRp are observed based on molecular docking. In conclusion, essential oils could target proteins related to the SARS-CoV-2 entry and replication. Further studies with improved and uniform study designs should be carried out to optimize essential oils as COVID-19 therapies.

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. This study employed bibliometric analysis based on the metadata of published literature indexed in the Scopus database. The search was performed on December 15^th, 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. 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). 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.