Propolis and its potential against SARS-CoV-2 infection mechanisms and COVID-19 disease: Running title: Propolis against SARS-CoV-2 infection and COVID-19.

Propolis, a resinous material produced by honey bees from plant exudates, has long been used in traditional herbal medicine and is widely consumed as a health aid and immune system booster. The COVID-19 pandemic has renewed interest in propolis products worldwide; fortunately, various aspects of the SARS-CoV-2 infection mechanism are potential targets for propolis compounds. SARS-CoV-2 entry into host cells is characterized by viral spike protein interaction with cellular angiotensin-converting enzyme 2 (ACE2) and serine protease TMPRSS2. This mechanism involves PAK1 overexpression, which is a kinase that mediates coronavirus-induced lung inflammation, fibrosis, and immune system suppression. Propolis components have inhibitory effects on the ACE2, TMPRSS2 and PAK1 signaling pathways; in addition, antiviral activity has been proven in vitro and in vivo. In pre-clinical studies, propolis promoted immunoregulation of pro-inflammatory cytokines, including reduction in IL-6, IL-1 beta and TNF-α. This immunoregulation involves monocytes and macrophages, as well as Jak2/STAT3, NF-kB, and inflammasome pathways, reducing the risk of cytokine storm syndrome, a major mortality factor in advanced COVID-19 disease. Propolis has also shown promise as an aid in the treatment of various of the comorbidities that are particularly dangerous in COVID-19 patients, including respiratory diseases, hypertension, diabetes, and cancer. Standardized propolis products with consistent bioactive properties are now available. Given the current emergency caused by the COVID-19 pandemic and limited therapeutic options, propolis is presented as a promising and relevant therapeutic option that is safe, easy to administrate orally and is readily available as a natural supplement and functional food.

The effect of propolis supplementation on clinical symptoms in patients with coronavirus (COVID-19): A structured summary of a study protocol for a randomised controlled trial.

OBJECTIVES: This study aims to assess the effect of propolis supplementation on clinical symptoms in patients with coronavirus (COVID-19). TRIAL DESIGN: This is a Double-Blind, Placebo-Controlled, Parallel Arm, Randomized Phase ΙΙ Clinical Trial. PARTICIPANTS: Patients with the confirmed COVID-19 based on the PCR test are eligible to participate in the trial if they are 18 to 75 years of age and have no history of the current use of warfarin or propolis supplement and presence of sensitivity to bee products. Patients will be recruited from the Al-Zahra hospital in Isfahan city, Isfahan, Iran. INTERVENTION AND COMPARATOR: Participants (N=40) in the intervention group will receive an identical propolis tablet (containing 300 mg Iranian green propolis extract) three times a day for a period of 2 weeks. Participants (N=40) in the control group will receive an identical placebo tablet (containing 300 mg microcrystalline cellulose) three times a day for 2 weeks. All tablets are prepared by the Reyhan Naghsh Jahan Pharmaceutical Co., Isfahan, Iran. MAIN OUTCOMES: The main outcomes are changes in the coronavirus disease's clinical symptoms including duration and severity from baseline to the end of 2 weeks. RANDOMIZATION: Eligible patients will be randomly allocated in a 1:1 ratio to the intervention or control group. Randomization will be performed on the basis of permuted block sizes of 4 and will be stratified according to sex categories. Randomization sequences will be prepared by the trial's pharmacist with the use of random-number tables. BLINDING (MASKING): The trial-group assignment will be concealed from all participants, clinicians, and investigators throughout the trial. To ensure blinding, randomization sequences will be kept in identical, opaque, sealed, sequentially numbered envelopes. Only the trial's pharmacist has access to the randomization list. Also, the placebo tablet will be similar to the propolis tablet in terms of texture, taste, color, odor, and weight. Both tablets will be provided in containers that are completely identical in weight, shape, labelling, and packaging. NUMBERS TO BE RANDOMIZED (SAMPLE SIZE): The calculated total sample size is 80 patients, with 40 patients in each group. TRIAL STATUS: The protocol is Version 1.0, October 10, 2020. Recruitment began August 22, 2020, and is anticipated to be completed by March 21, 2021. TRIAL REGISTRATION: The name of the trial register: The effect of propolis supplementation on clinical symptoms in patients with coronavirus (COVID-19): A randomized, double-blind, placebo-controlled clinical trial. IRCT registration number: IRCT20200802048267N1 . Date of trial registration: 20 October 2020, retrospectively registered. FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest of expediting the dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol.

Optimization and evaluation of propolis liposomes as a promising therapeutic approach for COVID-19.

The present work aimed to develop an optimized liposomal formulation for enhancing the anti-viral activity of propolis against COVID-19. Docking studies were performed for certain components of Egyptian Propolis using Avigan, Hydroxychloroquine and Remdesivir as standard antivirals against both COVID-19 3CL-protease and S1 spike protein. Response surface methodology and modified injection method were implemented to maximize the entrapment efficiency and release of the liposomal formulation. The optimized formulation parameters were as follow: LMC of 60 mM, CH% of 20% and DL of 5 mg/ml. At those values the E.E% and released % were 70.112% and 81.801%, respectively with nanosized particles (117 ± 11 nm). Docking studies revealed that Rutin and Caffeic acid phenethyl ester showed the highest affinity to both targets. Results showed a significant inhibitory effect of the optimized liposomal formula of Propolis against COVID-3CL protease (IC50 = 1.183 ± 0.06) compared with the Egyptian propolis extract (IC50 = 2.452 ± 0.11), P < 0.001. Interestingly, the inhibition of viral replication of COVID-19 determined by RT_PCR has been significantly enhanced via encapsulation of propolis extract within the liposomal formulation (P < 0.0001) and was comparable to the viral inhibitory effect of the potent antiviral (remdesivir). These findings identified the potential of propolis liposomes as a promising treatment approach against COVID-19.