(M1130-01-04) Utilizing Hydroxypropyl Methylcellulose (HPMC) and Carrageenan in Nasal Spray Gel with Andrographis paniculata Extract for COVID-19 Prevention

Purpose: Coronavirus disease (COVID-19), a newly emerged respiratory illness, has a profound impact on health across humans and animals worldwide. This disease is triggered by the novel coronavirus SARS-CoV-2. Infection begins when the virus interacts with its host, leading to a series of events that include the virus attaching to host cells, followed by its replication, transcription, translation, assembly, and the release of new viral particles. Given this, there is growing interest in developing preventive strategies that interfere with these initial viral-host interactions. A notable strategy is the formation of a gel barrier on nasal epithelial cells to block viral entry. This study explores the development of an ion-sensitive nasal spray made from hydroxypropyl methylcellulose (HPMC) mixed with carrageenan, infused with Andrographis paniculata extract for its potential anti-SARS-CoV-2 effects. It also examines the impact of varying concentrations of HPMC and carrageenan in the ion-responsive in-situ gel for nasal application.

Methods: An Andrographis paniculata extract at a concentration of 10 µg/ml was tested for cytotoxicity on MTS assay vero E6 cells. Additionally, its anti-SARS-CoV-2 efficacy was evaluated using a TCID50 titration assay on the same cell type. To formulate an anti-SARS-CoV-2 nasal spray, the extract was used at an effective concentration in a prototype formulation. This formulation aimed to exploit the interaction between nasal mucus electrolytes and ion-sensitive polymers to form a protective gel barrier within the nasal cavity. Ion-gelation studies were performed to analyze how well a simulated nasal electrolyte solution interacted with the blended polymers in the nasal spray. The gel formation time was compared between the basic formula without polymers and the formula containing the simulated nasal electrolyte solution. Optimization of each polymer’s concentration was carried out using the "one factor at a time" method. The concentrations of HPMC tested ranged from 0.05% to 0.25% w/v, and for carrageenan, from 0.02% to 0.08% w/v.

Results: At a concentration of 10 µg/ml, Andrographis paniculata extract maintained over 80% cell viability on vero E6 cells, showing no significant changes in cell morphology or signs of cell necrosis. Moreover, at this concentration, the extract inhibited over 90% of SARS-CoV-2 activity in vero E6 cells. Consequently, this concentration was incorporated into a nasal spray formulation for its anti-SARS-CoV-2 properties. The formulated nasal spray effectively interacted with ions present in a simulated nasal electrolyte solution (Ca2+, Mg2+, and Na+). When applied to a membrane absorbing the simulated nasal electrolyte solution and water, the tail lengths of the developed spray were measured at 1.74±0.07 cm and 3.87±0.03 cm, respectively. It also showed a faster gel formation time compared to the base formula, recording 3.37±0.15 cm. Optimization studies applying the one factor at a time method revealed that 0.25%w/v of HPMC significantly reduced the gel formation time to 1.59±0.43 cm compared to higher lengths observed with other concentrations (4.63±0.28 cm to 5.00±0.12 cm). Thus, 0.25%w/v of HPMC was chosen to determine the optimal concentration of carrageenan, which, at concentrations ranging from 0.02 to 0.08%w/v, showed tail lengths of 1.88±0.22 cm, 1.99±0.52 cm, and 1.69±0.18 cm respectively, indicating minimal variation across these concentrations.

Conclusion: The polymer system consisting of HPMC and carrageenan demonstrated effective gel formation through ion-responsive interactions with electrolytes in the nasal cavity mucus. The study highlighted that increasing HPMC concentration directly enhances ion-responsive gel formation, while the contribution of carrageenan concentrations was less variable. Additionally, the promising anti-SARS-CoV-2 properties of Andrographis paniculata extract support its potential as a natural active ingredient in nasal formulations.

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Acknowledgements: The pathogen-related studies were performed in bio-safety laboratory level 3. This study was approved by Institutional Review Board number (NU-IRB 0283 and IRB no. 1066/66) from Research Human Ethic Committee and Institutional Biosafety Committee (Approval no. NUIBC MI 66-06-32 and CU-IBC 005/2023), Faculty of Pharmaceutical Sciences, Naresuan University, Thailand and Faculty of Medicine, Chulalongkorn University, Thailand respectively. The scholarships from Research and researcher for industries (RRI) program under National Research Council of Thailand with Ambrose Asia co., ltd. as co-contributor. The Canada-ASEAN Scholarships and Educational Exchanges for Development (SEED) program. The full knowledge and technical support from Cosmetics and Natural Products Research Center, Center of Excellence in Applied Medical Virology and Drug Development and Innovation Centre.