Ginkgo in the management of Covid-19

Ginkgo is widely used to treat peripheral vascular diseases, dementia, and age‐related macular degeneration. The beneficial effect of ginkgo on inflammation and microcirculation is well known by herbalists and naturopaths, however, ginkgo also have antiviral effects, which may be beneficial in Covid-19.

Ginkgo contains various phytochemicals with broad‐spectrum antiviral activity that can affect the viral life cycle stages, including viral binding, fusion, viral entry, protein expression, and viral protein assembly and release.

A key mechanism is the blocking of 3-chymotrypsin-like protease, the main protease that is pivotal for the replication of SARS-CoV-2 (Xiong et al. 2021). Ginkgo has also been shown to inhibit fusion of enveloped viruses, thereby preventing the entry of the virus into the host. (Borenstein et al. 2020). SARS-Co-2 is an enveloped virus suggesting ginkgo may be effective in reducing its fusion and entry.

Ginkgo also exert wide‐ranging anti‐inflammatory effects by inhibiting proinflammatory and activating anti‐inflammatory cytokines. These findings suggest that ginkgo improves the innate immune response during viral infections. In mice models of allergy, ginkgo attenuated allergic inflammation of the airways; suggesting a potential use in the treatment of inflammatory conditions of the respiratory system.

The potential activities of ginkgo in Covid-19 are illustrated in the figure below.

Role of Ginkgo biloba (GB) in COVID‐19: GB inhibits replication of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) through inhibition of 3‐chymotrypsin like protease (3CLpro). GB inhibits the release of proinflammatory cytokines via suppression of nuclear factor kappa B (NF‐κB) and node‐like receptor pyrin 3 (NLRP3) inflammasome. Ginkgo inhibits thrombosis and endothelial dysfunction (ED) via inhibition of angiotensin II (Ang II) and mitogen‐activated protein kinase (MAPK). Also, gin reduces the activity of cyclooxygenase (COX) and lipoxygenase (LOX) involved in releasing proinflammatory cytokines. GB antioxidant effects inhibit the expression of toll‐like receptor 4 (TLR4) and myeloid differentiation primary response (MyD88), thereby attenuating proinflammatory cytokines. GB antioxidant effects also inhibit cytokine storm and the development of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). GB blocks the development of the sympathetic storm, which increases the risk of ALI, ARDS, cytokine storm, and release of proinflammatory cytokines (Al-Kuraishy et al. 2022).

The authors conclude that ginkgo may attenuate the acute lung injury and acute respiratory distress syndrome in COVID-19 and that it should be testing in a clinical trial (Al-Kuraishy et al. 2022).

Monograph extract EGb 761

By default, the German ginkgo extract known as EGb 761 has become the monograph standard. This extract has a ratio of 50:1 (dry leaf to final extract) and it is standardised to contain 24% flavone glycosides (primarily quercetin, kaempferol and isorhamnetin) and 6% terpene lactones (2.8-3.4% ginkgolides A, B and C, and 2.6-3.2% bilobalide). Ginkgolide B and bilobalide account for about 0.8% and 3% of the total extract, respectively. The original extract is also known by its trade names Rökan, Tanakan, and Tebonin.

Dosage

The typical dosage of the standardised ginkgo is 120 mg extract of EGb or equivalent extract. However, it is likely that the dose needs to be at the high end of 240 mg daily in the prevention and treatment of Covid-19.

Al-Kuraishy, H. M., A. I. Al-Gareeb, A. Kaushik, M. Kujawska, and G. E. Batiha. 2022. 'Ginkgo biloba in the management of the COVID-19 severity', Arch Pharm (Weinheim): e2200188.

Boozari, Motahareh, and Hossein Hosseinzadeh. 2021. 'Natural products for COVID-19 prevention and treatment regarding to previous coronavirus infections and novel studies', Phytotherapy Research, 35: 864-76.

Borenstein, Ronen, Barbara A. Hanson, Ruben M. Markosyan, Elisa S. Gallo, Srinivas D. Narasipura, Maimoona Bhutta, Oren Shechter, Nell S. Lurain, Fredric S. Cohen, Lena Al-Harthi, and Daniel A. Nicholson. 2020. 'Ginkgolic acid inhibits fusion of enveloped viruses', Scientific Reports, 10: 4746.

Xiong, Yuan, Guang-Hao Zhu, Hao-Nan Wang, Qing Hu, Li-Li Chen, Xiao-Qing Guan, Hui-Liang Li, Hong-Zhuan Chen, Hui Tang, and Guang-Bo Ge. 2021. 'Discovery of naturally occurring inhibitors against SARS-CoV-2 3CLpro from Ginkgo biloba leaves via large-scale screening', Fitoterapia, 152: 104909.