Nutraceuticals of nano-betel (Piper betle L.) leaves: prevent COVID-19 and oral cavity disease

Introduction:  Betel leaf is very popular in Asia and known to have a function as traditional medicine. And is often referred to as the "Golden Heart of Nature". This is because the betel leaf has an effect such as antimicrobial, antiviral, radioprotective, antioxidant, antiseptic, bactericidal, anti-inflammatory, antiallergic, wound healing, antiplatelet, antibacterial, antifungal, and immunomodulatory activity. Nutraceutical nano-betel leaf extract contains rich in minerals, vitamins, antioxidants, phenolic compounds, and essential oils. Effectively protects the mouth from pathogens. This research aims to review the nutraceuticals of nano-betel leaf extract to prevent COVID-19 and oral cavity disease. Methods:  This systematic review study was conducted through six steps: (1) framing the questions (based on theory); (2) Run a search (on Scopus, Google Scholar, EBSCO, ProQuest, and Science Direct publishing articles from 2020 to 2022); (3) Determine the relevant research; (4)  Determine the articles come from diverse backgrounds; (5) Extraction of data from individual studies; (6) Synthesis of results using the narrative method. Results:  Betel leaf contains nutrients for oral health, immunomodulators, and COVID-19, namely protein, amino acids, vitamins A, B, C, and K, as well as minerals such as Mg, K, Ca, Fe, I, P, Zn, essential oil (eugenol, hydroxylchavicol, allylpyrocatechol, quercetin, etc). Betel leaf nano extract has a significant role as antioxidants, anti-inflammatory, antimicrobial, and antivirus, which act as anti-oral cavity disease and anti-COVID-19. Betel leaf nano extract has a significant role in curing various oral cavity diseases related to COVID-19, including fungal infections, toothache, conjunctivitis, re-current HSV, oral ulcerations, xerostomia or decreased salivary flow, and gingivitis. Conclusion:  Betel leaf nano extract has a significant role in curing oral cavity disease and COVID-19. It is recommended that research into the oral disease and COVID-19 drugs combined with viable ingredients substances from betel leaf.