Table 2.
Clusters formed by keyword co-occurrence indicating the research hotspots.
| Cluster | Comprising keywords | Research hotspot(s) |
|---|---|---|
| Pre-COVID-19 | ||
| I | Essential oils, antifungal activity, antibiotics, edible film, chitosan, encapsulation, food safety, active packaging, biofilm, and nanoemulsion | Utilization of essential oil in food packaging |
| II | Toxicity, repellency, Aedes aegypti, insecticidal activity, larvicidal activity, fumigant toxicity, repellent, phytotoxicity, botanical insecticides, acute toxicity | Essential oils as insecticidal, larvicidal, and fumigant |
| III | Antioxidant activity, GC-MS, hydrodistillation, super critical fluid extraction, extraction, oil, anticholinesterase activity, volatile oil, HPLC, and oxidative stability | Separation and identification methods for essential oils |
| IV | Medicinal plants, lavender, natural products, aromatherapy, anxiety, pain, massage, stress, traditional medicine, and depression | Essential oil as pain, stress, and depression management |
| V | Antimicrobial, flavonoids, anti-inflammatory, polyphenols, DPPH, pharmacology, phytochemistry, biological activity, and terpenoids | Essential oil as antioxidant, anti-inflammatory, and antimicrobial agents |
| During COVID-19 | ||
| I | Antimicrobial activity, nanoemulsion, chitosan, encapsulation, carvacrol, stability, active packaging, edible films, food safety, thymol | Utilization of essential oil in food packaging |
| II | Toxicity, gas chromatography, insecticidal activity, repellency, larvicidal activity, integrated pest management, fumigant toxicity, botanical insecticides, eucalyptus, fungi | Essential oils as insecticidal, insect repellent, larvicidal, and fumigant |
| III | Flavonoids, secondary metabolites, phenolic compounds, antioxidants, oxidative stress, linalool, polyphenols | Antioxidant activities of essential oil |
| IV | Aromatherapy, COVID-19, anti-inflammatory, medicinal plants, pain, molecular docking, phytochemicals, lavender, antiviral, herbal medicine | Essential oils in COVID-19 management and their antiviral activities |
| V | Chemical composisiton, terpenes, lamiaceae, biological activities, phytochemistry, pharmacology, pharmacokinetics, antiproliferative, cytotoxic, bioactive compounds | Essential oils as anticancer agents |
| VI | Essential oil, GC-MS OR GS/MS, hydrodistillation, essentail oil compounds, volatile oil, α-pinene, myrtaceae, LC-MS, metabolomics, and extraction | Separation and identification methods for essential oils |
| VII | Essential oils, oregano, growth performance, poultry, immunity, gut health, thyme, plant extract, bacteria, and antimicrobial resistance | Utilization of essential oil in poultry |
| VIII | Antibacterial, antifungal, antifungal activity, biofilm, Staphylococcus aureus, eugenol, mycotoxins, nanoencapsulation, synergism, and Candida albicans | Antimicrobial activities of essential oils |
| COVID-19-focused | ||
| I | Anti-inflammatory, antibacterial, antimicrobial, antioxidant, antiviral, carvacrol, complementary medicine, phytomedicine, thymoquinone, essential oil | Essential oil as antioxidant, anti-inflammatory, and antimicrobial agents |
| II | 2019-nCoV, immunity, medicinal plants, phytochemicals, SARS-CoV, traditional Chinese medicine, traditional medicine, viral infections | Essential oils as immunomodulator against SARS-CoV-2 |
| III | Anxiety, aromatherapy, depression, mental health, and stress | Essential oils in managing depression and anxiety associated with COVID-19 |
| IV | Antiviral activity, bioactive compounds, COVID-19, docking, eucalyptus oil, herbal medicine, natural product | Antiviral activities of essential oils |
| V | Inflammation, natural compounds, natural products, nigella sativa, oxidative stress, pandemic, and SARS-CoV-2 | Essential oils in controlling inflammatory response associated with SARS-CoV-2 infection |
| VI | Chlorhexidine, mouthwashes, povidone-iodine, viral load, virucidal activity, and virus | Essential oils for mouth rinsing in managing COVID-19 |
| VII | Essential oils, GC-MS, in silico, molecular docking, terpenes, therapeutics | The use of computational approach in predicting antiviral activities of essential oils |
| VIII | Anosmia, olfactory training, SARS-CoV-2 | Essential oil usage in managing COVID-19 neuro symptoms |
| IX | ACE2, eucalyptus | Essential oil as ACE2 inhibitor |
Note: Clusters are ranked based on the size.