HKU scientists reveal orally administrated bismuth drug together with N-acetyl cysteine as a potential broad-spectrum anti-coronavirus cocktail therapy
A research team led by Professor Hongzhe SUN, Norman & Cecilia Yip Professor in Bioinorganic Chemistry from the Department of Chemistry, Faculty of Science, the University of Hong Kong (HKU), in collaboration with Dr Shuofeng YUAN, Assistant Professor from the Department of Microbiology, Li Ka Shing Faculty of Medicine, discovered that orally administrated bismuth drug colloidal bismuth subcitrate (CBS) together with N-acetyl cysteine (NAC) could be a broad-spectrum anti-coronavirus cocktail therapy. Oral administration of the cocktail suppresses the replication cycle of the virus, reduces viral loads in the lung and ameliorates virus-induced pneumonia in a hamster infection model. Not only could NAC stabilise bismuth-containing metallodrugs at stomach-like conditions but also enhance the uptake of bismuth drugs in tissues (e.g. lung) and antiviral potency through oral administration. Bismuth subsequently suppressed virus replication of a panel of clinically relevant coronaviruses, including Middle East respiratory syndrome-related coronavirus (MERS-CoV), Human coronavirus 229E (hCoV-229E) and Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its alpha variant (B.1.1.7) by inactivating multiple essential viral enzymes. The findings provided insights into the development of inorganic pharmaceutics and a new therapeutic approach for viral infections. The ground-breaking findings have been published in a leading chemical journal, Chemical Science and a related patent has been filed in the US. Background SARS-CoV-2 is the causative agent of the Coronavirus Disease 2019 (COVID-19) pandemic which leads to around five million confirmed cases, including 323,000 deaths globally. Although several vaccines have been approved for emergency use worldwide, increasing cases of people getting infected with COVID-19 are reported despite being fully vaccinated. The emergence of SARS-CoV-2 variants like Omicron and Delta variants associated with enhanced transmissibility and reduced sensitivity to vaccine-induced protection poses a continuous threat to global health. There is an urgent need for safe and effective therapeutic options for COVID-19 which remain scarce. Remdesivir was the first drug approved by the US Food and Drug Administration (FDA) for the treatment of COVID-19. However, patients can only receive remdesivir treatment via intravenous route as in-patients as the oral formulation of this drug is still not available. For most COVID-19 patients with mild to moderate disease, an orally available anti-SARS-CoV-2 drug would help to facilitate out-patient treatment and reduce the burdens of healthcare facilities. Even though the US FDA issued emergency use authorisation for the oral tablet-form candidates from pharmaceutical giants Pifzer and Merck which reported significant reduction of the risk of hospitalisation or death, their antiviral efficacy, long-term safety and worldwide availability spark uncertainties. Therefore, it is of utmost urgency for renewed efforts to evaluate the existing repertoire of FDA-approved drugs on a wider scale and by a novel strategy. Key findings The research team previously screened a set of metallodrugs and related compounds and identified ranitidine bismuth citrate (RBC, commercial name: Pylorid), a drug in clinical use for the treatment of Helicobacter pylori infection, as a potent anti-SARS-CoV-2 agent both in vitro and in vivo. Pylorid exhibited low cytotoxicity and protected SARS-CoV-2-infected cells with a high selectivity index which demonstrated the high clinical potential of bismuth(III)-drugs or other metallodrugs for the treatment of SARS-CoV-2 infection. The related works were published in Nature Microbiology in 2020. RBC, as well as other related bismuth drug(s), e.g., colloidal bismuth subcitrate (CBS) and bismuth salicylate (BSS), acts to precipitate in gastric juice and form a protective coating on the gastric wall, which leads to a hindered absorption in gastrointestinal tract. The findings revealed that NAC could prevent the hydrolysis of CBS in simulated gastric juice buffer (pH 1.2) and sodium bicarbonate buffer (pH 9.2), which form a highly stable and water-soluble Bi(III) thiolate complex, [Bi(NAC)3]. The combined use of NAC could significantly enhance the permeability of bismuth in parallel artificial membrane model, the human intestinal epithelial cancer cell line (Caco-2) model, and a modified ex vivo everted rat gut sac model. The thiolated bismuth could undergo fast thiol exchange with thiol groups in glycoproteins, which potentially increase both the lipophilicity and membrane permeability of bismuth, thus further enhancing the oral absorption of bismuth drugs. The in vivo pharmacokinetics data also consistently demonstrate that compared with the administration of CBS in the absence of NAC, the co-administration of CBS with NAC led to a remarkably improved bismuth uptake profile in both blood and lung tissues. The studies demonstrated the oral efficacy of CBS+3NAC as well as BSS+3NAC on the suppression of SARS-CoV-2 replication in vivo as evidenced by the substantial reduction of viral loading in the lungs based on viral RNA genome copy number and the ameliorated virus-associated lung pathology after oral administration of CBS+3NAC. The therapeutic dosage of drugs induced only reversible nephrotoxicity and no systematic toxicities. More importantly, CBS+3NAC inhibits the replication of a broad range of epidemic and seasonal CoVs, including SARS-CoV-2 (B.1.1.7), MERS-CoV, and hCoV-229E. The pan-inhibitory activity of bismuth drugs against various CoVs may stem from their abilities to target multiple key viral cysteine enzymes in the viral replication cycles, including papain-like protease (PLpro), main protease (Mpro), helicase (Hel) and angiotensin-converting enzyme 2 (ACE2). Image 1. Combinatorial CBS and NAC exhibit broad-spectrum anti-CoVs potency both in vitro and in vivo. (A) Scheme depicting the therapeutic treatment via oral administration of vehicle, CBS (300 mg/kg) or BSS (300 mg/kg), NAC (370 mg/kg) and CBS (300 mg/kg)+3NAC (370 mg/kg) or BSS (300 mg/kg)+3NAC (405 mg/kg), given at Day -2, -1, 0 and 1 and the hamsters were challenged by virus at Day 0; Tissue samples were collected at two days after infection. (B) Viral yield in lung tissue of hamster receiving treatment of vehicle, CBS, NAC, and CBS+3NAC. (C) Viral yield in lung tissue of hamster receiving treatment of vehicle, BBS, and BSS+3NAC. (D) Cytokine IL-6 gene expression level. (E) CBS+3NAC suppressed replication of human-pathogenic coronaviruses in human cellular models in a dose-dependent manner, specifically for SARS-CoV-2 in Vero E6 cells; SARS-CoV-2 (B.1.1.7 variant) in Vero E6 cells; MERS-CoV in Vero E6 cell and HCoV-229E in HELF cell. Image 2. Proposed mechanism of action for orally administrated colloidal bismuth subcitrate together with N-acetyl cysteine as a broad-spectrum anti-coronavirus cocktail therapy. The pan-inhibitory activity of bismuth drugs against various CoVs may stem from their abilities to target multiple viral enzymes in the viral replication cycles. CBS as well as related metallodrugs could inactivate the viral cysteine protease through either targeting the key cysteine residue in the active site (PLpro and Mpro) or structural zinc-finger domain (PLpro and Hel) or even other zinc metalloproteins in human cells (ACE2) that are tightly associated with viral entry. Image 3. Professor Hongzhe SUN (Norman & Cecilia Yip Professor in Bioinorganic Chemistry and Chair Professor of Chemistry) and his research team. From the right: Miss Suyu WANG (PhD student, Department of Chemistry); Dr Hongyan LI (Senior Research Assistant, Department of Chemistry); Professor Hongzhe SUN, Dr Runming WANG (Postdoctoral Fellow, Department of Chemistry); Dr Shuofeng YUAN (Assistant Professor, Department of Microbiology, HKUMed); Dr Jasper Fuk-Woo CHAN (Clinical Associate Professor, Department of Microbiology, HKUMed). About the research team The research was conducted by a team led by Professor Hongzhe SUN, Chair Professor of Chemistry, Department of Chemistry. Professor Hongzhe SUN and Dr Shuofeng YUAN, Assistant Professor from the Department of Microbiology, Li Ka Shing Faculty of Medicine are co-corresponding authors. Postdoctoral fellow Dr Runming WANG, Clinical Associate Professor Jasper Fuk-Woo CHAN and Miss Suyu WANG are co-first authors. Other HKU scientists contributing to the research included Dr Hongyan Li, Senior Research Assistant (Chemistry), Postdoctoral fellow Dr Jiajia Zhao (Pharmacy, CUHK), Miss Tiffany Ka-Yan Ip, PhD student (Chemistry), Professor Joan Zhong ZUO, Professor (Pharmacy, CUHK), Professor Kwok-Yung YUEN, Chair Professor (Department of Microbiology, HKUMed). The work was supported by Innovation Research Commission, Research Grants Council, Health and Medical Research Fund of Hong Kong SAR, and The University of Hong Kong. About Professor Hongzhe SUN and Dr Shuofeng Yuan Professor Hongzhe SUN is a Norman & Cecilia Yip Professor in Bioinorganic Chemistry and Chair Professor of Chemistry at The University of Hong Kong. His research focuses on metalloproteins, the discovery of antimicrobial agents, and inorganic chemical biology. More information about Professor Hongzhe SUN and his research group can be found from their group’s webpage: https://chemistry.hku.hk/staff/hzsun/labPage/index.html Dr Shuofeng Yuan is an Assistant Professor at the Department of Microbiology and State Key Laboratory of Emerging Infectious Diseases, The University of Hong Kong. More information about Dr Shuofeng Yuan, and his research group can be found from their group’s webpage: http://www.microbiology.hku.hk/02_HKU_Staff_Dr_SY_Yuan.html About the research paper:https://doi.org/10.1039/D1SC04515F
Faculty of Science scoops four awards in 2021/22 Collaborative Research Fund (CRF) Group Research Projects
In the latest announcement of the Research Grants Council (RGC) in the 2021/22 funding exercise, the Faculty of Science has secured exceptional results under the Collaborative Research Fund (CRF). Established by the University Grants Committee (UGC), the award of CRF Group Research Projects is to encourage and support multi-investigators in diverse disciplines to engage in more creative and high-quality cross-disciplinary projects. Among the 25 CRF Group Research Projects funded by the RGC, HKU has been funded with seven projects as coordinating institution, in which four led by the Faculty have secured a funding of over HK$24.8 Million. Among the four awarded projects, two are from Department of Chemistry, one from Earth Sciences and the other one from Physics. Details of the awarded projects are appended below: Department Project Title Project Coordinator RGC Fund Approved Project Period Chemistry Functional supramolecular and metallosupramolecular materials and biomaterials — From synthetic challenges to controlled supramolecular assembly, functions and application studies 超分子和金屬超分子功能材料及生物材料 - 從合成挑戰到超分子可控組裝、功能及應用研究 Professor Vivian Wing Wah YAM HK$7,480,000 3 years Chemistry Active fluid for enhanced thermal transport and energy harvesting 活性流體在傳熱和能源回收中的應用 Dr Jinyao TANG HK$4,559,740 3 years Earth Sciences Characterisation of ancient lake basins on Mars using advanced topographic modelling and innovative spectroscopic techniques 基於先進地形建模與創新光譜技術的火星老湖泊盆地特徵研究 Dr Joseph MICHALSKI HK$4,621,350 3 years Physics Transport and dynamics of correlated quantum matter 關聯量子物態中的輸運和動力學 Professor Shunqing SHEN HK$8,160,000 3 years HKU Vice-President and Pro-Vice-Chancellor (Research) Professor Max Shen congratulated all successful applicants and their research teams. He said: “The grants are clear demonstration of the research competitiveness of the University’s faculties and investigators. Their success in obtaining funding further recognised the University’s excellent performance in teaching, learning, and research, and our researchers’ outstanding achievements and strengths. I hope HKU members will continue to address important problems in their fields with innovative ideas, so as to elevate the University’s research in a wide range of areas to world leading levels.” For more details about the funding results, please click here .
HKU scientists discover activation mechanisms in soybean for adaptation to saline soil in hope of improving agriculture productivity
Farmlands are turning more saline due to climate change, rising sea levels, expanding drylands, and groundwater depletion. This crisis is exacerbated by unsustainable farming practices. The resulting loss in crop yield threatens malnourished populations across the globe. Therefore, scientists are finding ways to boost crop resilience to salt stress to safeguard food security on this planet. Professor Mee-Len CHYE, Wilson and Amelia Wong Professor in Plant Biotechnology, and Dr Terry Shiu-Cheung LUNG, Research Assistant Professor, from the School of Biological Sciences at the University of Hong Kong (HKU) have unveiled the molecular mechanisms activating salt-induced adaptive changes in soybean, bringing hope in providing possible solutions for saline agriculture. The findings, published in the prestigious scientific journal The Plant Cell, offer new strategies to help plants combat soil salinity. Background Plants as sessile organisms strive for survival upon salt-induced stress by prompting actions including the modification of root architecture, generation of ion pumps, and production of specific metabolites. Acclimation requires numerous stress signalling molecules such as those belonging to two important lipid classes, termed ‘phosphatidic acid’ and ‘oxylipins’. Earlier, Professor Chye’s research team had shown that the generation of phosphatidic acid signals could be facilitated by a Class II acyl-CoA-binding protein (ACBP). ACBPs are highly conserved in eukaryotes and bind acyl-CoA esters, the activated form of fatty acids in lipid metabolism. However, the processes that trigger the synthesis of oxylipins, the oxygenated derivatives of polyunsaturated fatty acids, and crosstalk between phosphatidic acid and oxylipin signals had remained elusive until now. Key findings When Professor Chye’s team examined soybean roots in a salt solution, surprisingly Class II ACBP3 and ACBP4 variant proteins smaller than the native forms emerged during the first few hours of treatment. “These proteins were truncated because their pre-mRNAs were cut and rejoined in an atypical way, commonly known as ‘alternative splicing’. Luckily, we caught them at the right moment to discover this phenomenon never before seen in plant ACBPs,” commented Professor Chye. Her research team found that the overexpression of the native and truncated ACBP4 rendered soybean hairy roots more salt-sensitive and salt-tolerant than the control, respectively (see Figure 1). Similarly, transgenic Arabidopsis overexpressing truncated ACBP3 were more salt-tolerant than the control, while transgenic Arabidopsis overexpressing native ACBP3 and ACBP4 were more salt-sensitive (see Figure 2). From microscopy, molecular and biochemical analyses, a model (see Figure 3) was formulated to illustrate the mechanistic role of ACBP3 and ACBP4 in activating the generation of oxylipin signals, as well as crosstalk between oxylipins and phosphatidic acid during signalling. Professor Chye briefly explained, “Oxylipin signals are generated by lipoxygenases. Under normal conditions, the enzymes are inactive when they complex reversibly with ACBPs and acyl-CoAs. Under salinity, the enzymes are activated when phosphatidic acid and truncated ACBPs compete for binding with the components of this complex, which eventually dissociates.” Professor Chye hopes to unveil other components in the oxylipin signalling mechanism to further understand the salinity response. Apart from that, her team is currently exploring the potential of enhancing salt tolerance in soybean and other plant crops by a genetic engineering approach. If this innovation is successfully implemented, crop yield will be less impacted by soil salinity to promote food production in view of climate change. Professor Chye also expressed that there is no greater honour than receiving an endowed professorship established with a generous donation from Dr Wilson and Mrs Amelia Wong for using plant biotechnology to ensure food supply for a sustainable future. Figure 1. Overexpression of truncated ACBP4 variant promotes salt tolerance in soybean hairy roots. Soybean hairy roots overexpressing the native (bottom middle) and truncated (bottom right) forms of ACBP4 were more salt-sensitive and salt-tolerant than the vector-transformed control (bottom left), respectively. Under normal conditions, the hairy roots of all genotypes grew similarly (top panels). Scale bar = 1 cm. Figure 2. Overexpression of truncated ACBP3 variants promotes salt tolerance in Arabidopsis. Transgenic Arabidopsis overexpressing the native Class II ACBPs and truncated ACBP3 variants were more salt-sensitive and salt-tolerant than the vector-transformed control, respectively. Scale bar = 1 cm. Figure 3. Model for ACBP3/ACBP4-regulated generation of oxylipin signals during the salinity response. Under normal conditions, ACBP binding with acyl-CoAs (C18:2 and C18:3-CoAs) facilitates sequestration of an inactive lipoxygenase. High salinity triggers dissociation of this complex by a dual mechanism. First, phosphatidic acid signals compete with acyl-CoAs for ACBP binding. Second, pre-mRNAs are cut and rejoined in an unusual way (known as alternative splicing) to produce ACBP variants lacking the lipoxygenase-interacting domain. Thus, the lipoxygenase is activated to generate oxylipin signals for adaptive responses. About the research team The research team was led by Professor Mee-Len CHYE, Wilson and Amelia Wong Professor in Plant Biotechnology from the School of Biological Sciences at HKU. This project was conducted in collaboration with Professor Hon-Ming LAM, Choh-Ming Li Professor of Life Sciences at The Chinese University of Hong Kong and Director of the State Key Laboratory of Agrobiotechnology (CUHK). Dr Terry Shiu-Cheung LUNG, Research Assistant Professor from the School of Biological Sciences at HKU, is the first and co-corresponding author of the journal paper. Other HKU scholars who contributed to this research include Ms Sze Han LAI, Dr Haiyang WANG, Ms Xiuying ZHANG, Dr Ailin LIU, and Dr Ze-Hua GUO. This work was supported by the Wilson and Amelia Wong Endowment Fund, Hong Kong Research Grants Council Areas of Excellence Scheme (AoE/M-403/16), and Innovation and Technology Fund (Funding Support to State Key Laboratory of Agrobiotechnology). About the paper The journal paper entitled “Oxylipin signaling in salt-stressed soybean is modulated by ligand-dependent interaction of Class II acyl-CoA-binding proteins with lipoxygenase” was published by Shiu-Cheung Lung, Sze Han Lai, Haiyang Wang, Xiuying Zhang, Ailin Liu, Ze-Hua Guo, Hon-Ming Lam and Mee-Len Chye in The Plant Cell. The full text of this paper is open for free access from here. For details on Wilson and Amelia Wong Professorship in Plant Biotechnology, please visit here.