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A Nasal Spray Solution of Grapefruit Seed Extract plus Xylitol Displays Virucidal Activity Against SARS-Cov-2 In Vitro

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Abstract

ABSTARCT The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the ongoing pandemic coronavirus disease 2019 (COVID-19) has triggered worldwide concerted efforts in an attempt to identify effective therapies. In the present study, we have identified two candidate agents with potential activity against SARS-CoV-2 which can be administered intranasally, namely, xylitol and grape seed fruit extract (GSE). A commercially available nasal spray (Xlear) combining xylitol and GSE has been available for years, but the antiviral effects of this solution have not been documented. This in vitro study examined the virucidal effect of Xlear against SARS-CoV-2. To this end, two independent sets of experiments were carried out to test the hypothesis that Xlear is an effective (Experiment I) and replicable (Experiment II) means to deactivate SARS-CoV-2. When tested against SARS-CoV-2, the test compound GSE 0.2% was the only compound effective at reducing >3 log10 CCID50 infectious virus from, 3.67 log10 CCID50/0.1 mL to an undetectable amount of infectious virus. The present results validated by two independent sets of experiments, performed by different labs, on different viral strains, provide early evidence to encourage further pilot and clinical studies aimed at investigating the use of Xlear as a potential treatment for COVID-19
Journal: Draft 1
Type: Original Research (Basic Science) 2
Abstract text: 199 3
Text: 2272 4
5
6
A Nasal Spray Solution of Grapefruit Seed Extract plus Xylitol Displays 7
Virucidal Activity Against SARS-Cov-2 In Vitro 8
9
Gustavo Ferrer, M.D.1,2 Arian Betancourt, M.D. 2; Camille Celeste Go, M.D. 2; Hector Vazquez, 10
MD 2; Jonna B. Westover, Ph.D.3; Valeria Cagno, Ph.D. 4; Caroline Tapparel, Ph.D. 4; Marcos A. 11
Sanchez-Gonzalez, MD, Ph.D.2,5*
12
1 Medical Innovations, Nova Southeastern University, Davie, FL, USA 13
2 Research & Development, Aventura Pulmonary Institute, Miami, FL, USA 14
3 Institute for Antiviral Research, Utah State University, Logan, Utah, USA 15
4Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of 16
Geneva, Geneva, Switzerland 17
5 Lake Erie College of Osteopathic Medicine, Bradenton, FL, USA 18
19
20
21
*Correspondence: 22
Marcos A. Sanchez-Gonzalez, MD, PhD 23
5000 Lakewood Ranch Blvd 24
Bradenton, FL, 34211 25
(850) 559-47676 26
msanchez-gonzalez@LECOM.edu 27
28
Declarations of interest: none 29
30
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ABSTARCT 31
32
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for the 33
ongoing pandemic coronavirus disease 2019 (COVID-19) has triggered worldwide concerted 34
efforts in an attempt to identify effective therapies. In the present study, we have identified two 35
candidate agents with potential activity against SARS-CoV-2 which can be administered 36
intranasally, namely, xylitol and grape seed fruit extract (GSE). A commercially available nasal 37
spray (Xlear) combining xylitol and GSE has been available for years, but the antiviral effects of 38
this solution have not been documented. This in vitro study examined the virucidal effect of 39
Xlear against SARS-CoV-2. To this end, two independent sets of experiments were carried out to 40
test the hypothesis that Xlear is an effective (Experiment I) and replicable (Experiment II) means 41
to deactivate SARS-CoV-2. When tested against SARS-CoV-2, the test compound GSE 0.2% 42
was the only compound effective at reducing >3 log10 CCID50 infectious virus from, 3.67 log10 43
CCID50/0.1 mL to an undetectable amount of infectious virus. The present results validated by 44
two independent sets of experiments, performed by different labs, on different viral strains, 45
provide early evidence to encourage further pilot and clinical studies aimed at investigating the 46
use of Xlear as a potential treatment for COVID-19 47
48
KEYWORDS: severe acute respiratory syndrome coronavirus, xylitol, grapefruit seed extract, 49
intranasal spray 50
51
52
53
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1 Introduction 54
The initial global outbreak of the severe acute respiratory syndrome coronavirus 2 55
(SARS-CoV-2), responsible for the ongoing pandemic coronavirus disease 2019 (COVID-19), 56
was initially identified in Wuhan, China in December 2019. As of July 2020, there were more 57
than 13.3 million confirmed cases worldwide, with total deaths exceeding 573,000 (Dong et al., 58
2020). Worldwide concerted efforts have been made in an attempt to characterize the disease and 59
identify effective therapies targeting SARS-CoV-2 including lines of studies focusing on the 60
route of infection, the potential routes of administration of therapeutic agents as well as the 61
potential efficacy of antiseptics (Meister et al., 2020). In this vein, a landmark study found that 62
the coronavirus infects the nasal cavity via the angiotensin-converting enzyme 2 (ACE2) protein 63
which appears to be the host-cell receptor for SARS-CoV-2 (Hoffmann et al., 2020). Since the 64
nasal epithelium cells have the highest percentage of ACE2 expressing ciliate cells in the 65
proximal airways, it is plausible to suggest that pharmacological agents such as sprays that are 66
used via the intranasal route of administration might be optimal candidates for providing 67
effective therapies against COVID-19 (Jia et al., 2005).
68
In a recent literature review conducted by Higgins et al. it is highlighted that intranasal 69
drug delivery represents an important area of research for viral diseases and COVID-19 (Higgins 70
et al., 2020). They concluded that the intranasal method of drug delivery has potential relevance 71
for future clinical trials in the setting of disease prevention and treatment of SARS-CoV-2 in 72
addition to other viral diseases (Higgins et al., 2020). Subsequently, Siddiqi et.al (2020), in a 73
diagram of COVID-19 disease progression, illustrated that the viral response phase is highest 74
during the early infection of the disease process, of which patients manifest mild constitutional 75
symptoms. Taken together the aforementioned studies support our rationale that therapeutic 76
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strategies should be aimed at reducing the viral load in the nose by targeting this mild-moderate 77
phase of the disease process, and hence the use of a nasal spray might be an effective means to 78
accomplish this therapeutic strategy. 79
In the present study, we have identified two candidate agents with potential activity 80
against SARS-CoV-2 which can be administered intranasally, namely, xylitol and grape seed 81
fruit extract (GSE). Xylitol, a sweetener with antimicrobial and anti-inflammatory properties, 82
has been shown effective in decreasing the incidence of dental caries and improving chronic 83
rhinitis as well as important microbiota and immunological modulatory effects (Akgül et al., 84
2020; Haukioja et al., 2008; Weissman et al., 2011; Xu et al., 2016). Xylitol has been reported to 85
have multiple health benefits as well as is generally safe and well-tolerated for most adults in 86
doses up to 35 grams per day and up to 20 grams per day in children (Salli et al., 2019; Storey et 87
al., 2007; Ur-Rehman et al., 2015). A derivative of grapefruit seeds, GSE, is associated with 88
abundant health benefits due to the presence of antioxidants and proanthocyanidin complexes 89
(Chacón et al., 2009). Also, GSE has been documented to have inhibitory effects against the 90
avian influenza virus, Newcastle disease virus, infections bursal disease virus, as well as other 91
pathogenic enteric viruses (Komura et al., 2019; Su and D'Souza, 2011). A commercially 92
available nasal spray combining xylitol and GSE, marketed as Xlear (American Fork, UT, USA), 93
has been widely used in the United States for several decades, but the antiviral effects of this 94
solution have not been documented. Accordingly, the aim of the present in vitro study was to 95
examine the virucidal effect of Xlear against SARS-CoV-2. To this end, two independent sets of 96
experiments were carried out to test the hypothesis that Xlear is an effective (Experiment I) and 97
replicable (Experiment II) means to deactivate SARS-CoV-2 the causative microorganism of 98
COVID-19. 99
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100
2 MATERIALS AND METHODS 101
2.1 Experiment I: Xlear Virucidal Activity Efficacy 102
2.1.1 Procedure 103
SARS-CoV-2, USA-WA1/2020 strain, virus stock was prepared before testing by 104
growing 2 passages in Vero 76 cells. Culture media for prepared stock (test media) was 105
MEM with 2% fetal bovine serum (FBS) and 50 µg/mL gentamicin. Human rhinovirus 16, 106
strain 11757 purchased from ATCC (Gaithersburg, Maryland, USA), was grown in 3 107
passages of HeLa cells in MEM with 2% fetal bovine serum (FBS), 25 mM MgCl2, and 50
108
µg/mL gentamicin. Test media is the growth media with 5% FBS. 109
2.1.2 Virucidal Assay 110
Test compounds including commercially available Xlear containing purified water, 111
11% Pure Xylitol (Shandon Lujian, Shandong, China), 0.6%NaCL (Saline), and 0.015% 112
GSE (Chemie Research & Manufacturing Co., Casselberry, FL, USA) were obtained from 113
the manufacturer in liquid form and stored at room temperature. The test compound 11% 114
xylitol in saline was diluted 1:2 with water before testing. Each solution was mixed directly 115
with virus stock so that the final concentration was 90% of each test compound and 10% 116
virus stock. A single concentration was tested in triplicate. Test media without virus was 117
added to duplicate tubes of the compounds to serve as toxicity and neutralization controls. 118
Ethanol (90%) was tested in parallel as a positive control and water only as a virus control. 119
The test solutions were incubated at room temperature (22 ± 2ºC) for 15 minutes with 120
SARS- CoV-2 or Rhinovirus-16. The solutions were then neutralized by a 1/10 dilution in 121
the test media of each specific virus. The virucidal assays were performed in triplicate, then 122
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after neutralization, the triplicate samples were pooled, serially diluted, and assayed for 123
infectious virus. 124
2.1.3 Virus Quantification 125
The surviving virus from each sample was quantified by standard end-point 126
dilution assay. Briefly, the neutralized samples were pooled and serially diluted using 127
eight log dilutions in test medium. Then 100 µL of each dilution was plated into 128
quadruplicate wells of 96-well plates containing 80-90% confluent Vero 76 (SARS-CoV-129
2) or HeLa cells (Rhino-16). The toxicity controls were added to an additional 4 wells of 130
Vero 76 or HeLa cells and 2 of those wells at each dilution were infected with virus to 131
serve as neutralization controls, ensuring that the residual sample in the titer assay plate 132
did not inhibit growth and detection of the surviving virus. Plates were incubated at 37 ±
133
2ºC with 5% CO2 for 5 days and at 33 ± 2ºC with 5% CO2 for 4 days for the SARS-CoV-2
134
assay and the Rhinovirus-16 assay, respectively. Each well was then scored for the
135
presence or absence of an infectious virus. The titers were measured using a standard 136
endpoint dilution 50% cell culture infectious dose (CCID50) assay calculated using the
137
Reed-Muench (1948) equation and the log reduction value (LRV) of each compound 138
compared to the negative (water) control was calculated. 139
2.2 Experiment II: Xlear Virucidal Activity Replication 140
2.2.1 Procedure 141
SARS-CoV2/Switzerland/GE9586/2020 virus stock was amplified and titrated in 142
Vero E6 cells by plaque assay cultured in DMEM HG with 5% fetal bovine serum (FBS) 143
and 1% penicillin/streptomycin. 144
Dose-response Assay 145
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Xlear nasal spray was serially diluted in DMEM HG and incubated with SARS-CoV2 146
(MOI 0.003 corresponding to 200 pfu/well) for 1 hour at 37°C and subsequently added on Vero 147
E6 cells for 1 hour at 37°C. The inoculum was then removed, cells were washed and overlaid 148
with DMEM HG with 5% FBS and Avicel 0.8%. 48hpi cells were fixed with PFA 4% and 149
stained with crystal violet. Plaques were counted and percent of infection calculated in 150
comparison with untreated wells. The experiments were performed twice independently, and 151
each was performed in duplicate. 152
Virucidal Assay 153
Xlear spray was mixed in different concentrations with SARS-CoV2 stock (105pfu). The 154
compound was mixed directly with the virus solution with a final concentration of respectively 155
90%, 80%, 60%, or 20%. PBS was used as control. The solution and virus were incubated at 37 156
°C for 1 hour. The solution was then neutralized by a 1/10 dilution in test media. A 60% 157
condition was repeated in two independent experiments while the other dilutions were performed 158
in a single experiment in duplicate. 159
The infectious virus from each sample was quantified by standard end-point dilution 160
assay. 100 µL of each dilution were plated into quadruplicate wells of 96-well plates containing 161
80-90% confluent Vero 76 cells. Plates were incubated at 37ºC with 5% CO2 for three days. 162
Each well was then scored for the presence or absence of the virus. The end-point titers 163
(TCID50) values were calculated using the Reed- Muench (1948) equation. 164
2.2.2 Toxicity assay 165
Vero-E6 (13000 cells per well) were seeded in 96-well plate. Xlear was serially diluted in 166
DMEM supplemented with 5% FBS and added on cells for 1h, followed by a washout, addition 167
of DMEM supplemented with 5% FBS for additional 48h hours. MTT reagent (Sigma Aldrich) 168
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was added on cells for 3h at 37°C according to manufacturer instructions, subsequently cells 169
were lysed with pure DMSO and absorbance read at 570 nm. Percentages of viability were 170
calculated by comparing the absorbance in treated wells and untreated. 171
3 RESULTS 172
3.1 Experiment I 173
Virus titers and LRV of Rhinovirus-16 and SARS-CoV-2 when incubated with a 174
single concentration of the Xlear solutions are shown in Table 1. After a 15-minute contact 175
time, the Xlear nasal spray was not effective at reducing the infectious Rhino-16 virus. 176
When tested against SARS-CoV-2, the test compound GSE 0.2% was the only compound 177
effective at reducing >3 log10 CCID50 infectious virus from, 3.67 log10 CCID50/0.1 mL
178
to an undetectable amount of infectious virus (Table 1). The Xlear nasal spray and the 179
GSE 0.2% had some toxicity in the top rows (1/10 dilution of the test sample) which may 180
have contributed to the virucidal effect of the GSE. The 11% xylitol and 11% erythritol 181
had no cytotoxicity. The positive control and neutralization control performed as expected. 182
3.2 Experiment II 183
SARS-Cov2 is inhibited in the dose-response assay (Figure 1) by different concentrations of 184
Xlear spray. However, the dilution 1:2 in medium evidenced damage to the cells with almost 185
complete loss of the cells, while with the dilution 1:6 a partial damage to the cell was evidenced, 186
while no morphologic changes in cells were visible from dilution 1:12 onwards. These results 187
were further confirmed with toxicity assays (Figure 1b). 188
In the virucidal assays (Figure 2), Xlear showed virucidal activity at the different 189
concentrations tested. Complete inhibition of viral infectivity was observed for the 90%, 80%, 190
60% condition, and a reduction of 2.17 log of viral titer in the 20% condition. In this assay, the 191
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mixture of virus and Xlear was neutralized by a 1/10 dilution before addition on cells, therefore 192
diluting the compound below the toxic doses determined in the toxicity assay (Figure 1b). 193
194
4 DISCUSSION 195
The present study sought to evaluate the in vitro virucidal effects of a solution combining 196
xylitol and GSE in a nasal spray formulation known as Xlear. The novel results of this study 197
support our hypothesis that Xlear displays virucidal activity against SARS-CoV-2. The present 198
results validated by two independent sets of experiments, performed by different labs, on 199
different viral strains, provide early evidence to encourage further pilot and clinical studies 200
aimed at investigating the use of Xlear as a potential treatment for COVID-19. 201
Xlear is a solution of xylitol and GSE, in line with previous reports, the latter displayed 202
antiviral activity. Komura et al. demonstrated the efficacy of GSE as an antimicrobial agent on 203
avian pathogens including avian influenza virus, Newcastle disease virus, infectious bursal 204
disease virus, Salmonella Infantis, and Escherichia coli (Komura et al., 2019). Also, GSE has 205
shown similar antiviral activities against human enteric pathogens including Hepatitis A virus in 206
a dose-dependent manner (Su and D'Souza, 2011). Interestingly, GSE antiviral activity seems to 207
be particularly effective on enveloped viruses. Since SARS-CoV-2 is an enveloped virus the 208
GSE characteristics to induced or target the viral envelope should not be overlooked as candidate 209
therapies for COVID-19 emerge (Schoeman and Fielding, 2019). On the other hand, xylitol did 210
not show in vitro virucidal properties in the present study. However, it seems that the viral 211
protective effects of xylitol are evident in vivo a suggested by studies demonstrating ameliorating 212
effects against human respiratory syncytial virus and changes in the microbiota when consumed 213
orally (Uebanso et al., 2017; Xu et al., 2016). 214
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The precise mechanism of action of GSE is poorly understood. However, according to 215
the present virucidal tests, the active component of the spray is the GSE, which is in line with 216
previous reports demonstrating that the extract was is effective to inactivate different enveloped 217
and non-enveloped viruses (Su and D'Souza, 2011). 218
219
Moreover, it seems that the mechanism of action of GSE targets the viral adsorption (or viral 220
binding) to a greater extent than viral replication. It is worth mentioning that studies of the 221
precise mechanism of action of GSE are beyond the scope of this work. 222
As with any research study, the present experimental design is not free from some 223
limitations. The minimum time required for the Xlear solution to exert the virucidal effect was 224
not investigated. Furthermore, to assess the relevance of the time-dependent effect of Xylitol 225
effect in vivo, it will be important to verify if the addition of the spray-on cells previously 226
infected at nontoxic doses would exert a reduction of the viral titer. Also, whether pre-treating 227
the cells with the spray and subsequently adding the virus would decrease the rate of infection 228
would be needed to assess the possible preventive use of the nasal spray. 229
CONCLUSIONS 230
This study demonstrates the strong virucidal effects against SARS-CoV-2 of the Xlear 231
nasal spray compound with xylitol and GSE. Using a virucidal nasal spray could become a 232
cutting-edge element in the prevention and treatment of COVID-19 disease. To further ascertain 233
the impact of this nasal spray in SARS-CoV-2, we propose to perform further a randomized 234
placebo-controlled study of intranasally delivered Xlear in patients with mild to moderate SARS-235
CoV-2 and randomized placebo-controlled preventive trial in healthcare workers. 236
237
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Acknowledgments 238
The authors are grateful to Mr. Nathan Jones for donating the reagents and testing solutions for 239
this study. 240
241
Funding 242
The study was funded thanks to the financial support of the “Fondation privée des HUG” and the 243
Carigest Foundation to CT. 244
245
246
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Table 1. Virucidal efficacy of Xlear compounds against Rhinovirus-16 and SARS-CoV-2 298
after a 15-minute incubation with virus at 22 ± 2ºC. 299
300
301
302
303
a Log10 CCID50 of virus per 0.1 mL. The assay lower limit of detection is 0.67 Log10 304
CCID50/0.1 mL. 305
b LRV (log reduction value) is the reduction of virus compared to the virus control 306
307
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Figure 1. a) SARS-CoV-2 dose-response inhibition. Xlear was incubated at different dilutions 308
with SARS-CoV2 (200 pfu) for 1h at 37 C. At the end of the incubation, mixtures were serially 309
diluted and added for 1h at 37°C on Vero-E6 cells. Mixtures were then removed, and cells 310
overlaid with medium containing 0.8% avicel. Cells were fixed 48hpi and plaques were counted. 311
Results are mean and SEM of 2 independent experiments performed in duplicate. b) Xlear 312
toxicity evaluation. Different dilutions of the nasal spray were incubated for 1h (followed by 313
addition of medium for 47h) or for 48h on cells in DMEM 5% FBS. At the end of the incubation 314
MTT reagent was added on cells and percentages of viability were evaluated by comparing 315
treated and untreated wells. 316
317
318
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Figure 2. SARS CoV-2 virucidal assay. Xlear was incubated with SARS-CoV2 (5*105 pfu) for 319
1h at 37 C. At the end of the incubation, mixtures were serially diluted and added on Vero-E6 320
cells. Cells were fixed 48hpi and scored for presence or absence of cytopathic effect and 321
TCID50/ml was determined. Results are mean and SD of two independent experiments. 322
323
324
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Tested
Concentration Virus Tested Incubation
Time Virus
Titer a
LRV b
Xlear 90% Rhino-16 15-minute 5.0 0
Ethanol 90% Rhino-16 15-minute 1.5 3.17
Virus Control na Rhino-16 15-minute 4.67 na
Xlear 90% SARS-CoV-2 15-minute 3.0 0.67
GSE 0.2% in DI water 90% SARS-CoV-2 15-minute <0.67 3.0
Saline w/ 11% Xylitol 90% SARS-CoV-2 15-minute 3.5 0.17
Saline w/ 11% Erythritol 90% SARS-CoV-2 15-minute 4.3 0
Ethanol 90% SARS-CoV-2 15-minute <0.67 3.0
Virus Control na SARS-CoV-2 15-minute 3.67 na
(which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.
The copyright holder for this preprintthis version posted November 25, 2020. ; https://doi.org/10.1101/2020.11.23.394114doi: bioRxiv preprint
(which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.
The copyright holder for this preprintthis version posted November 25, 2020. ; https://doi.org/10.1101/2020.11.23.394114doi: bioRxiv preprint
(which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.
The copyright holder for this preprintthis version posted November 25, 2020. ; https://doi.org/10.1101/2020.11.23.394114doi: bioRxiv preprint
... The small powder size (1.7 um) and reasonably long shelf lifetime allow it to be used as a potential inhaled COVID-19 treatment option. Ferrer et al. evaluated the application of xylitol and grapefruit seed extract (GSE) as nasal sprays to reduce virus attachment to the nasal cells and thus as a preventive measure to curb viral infections not just for SARS-CoV-2 but also for other viral epidemics [19]. ...
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In response to the unmet need for effective treatments for symptomatic patients, research efforts of inhaled therapy for COVID-19 patients have been pursued since the pandemic began. However, inhalation drug delivery to the lungs is sensitive to the lung anatomy and physiology, which can be significantly altered due to the viral infection. The ensued ventilation heterogeneity will change distribution and thus dosimetry of inhaled medications, rendering previous correlations concepts? of pulmonary drug delivery in healthy lungs less reliable. In this study, we first reviewed the recent developments of inhaled therapeutics and vaccines, as well as the latest knowledge of the lung structural variations documented by CT of COVID-19 patients' lungs. We then quantified the volume ratios of the poorly aerated lungs and non-aerated lungs in eight COVID-19 patients, which ranged 2-8% and 0.5-3%, respectively. The need to consider the diseased lung physiologies in estimating pulmonary delivery was emphasized. Diseased lung geometries with varying lesion sites and complexities were reconstructed using Statistical Shape Modeling (SSM). A new segmentation method was applied that could generate patient-specific lung geometries with an increased number of branching generations. The synergy of the CT-based lung segmentation and SSM-based airway variation showed promise for developing representative COVID-infected lung morphological models and investigating inhalation therapeutics in COVID-19 patients. Doi: 10.28991/SciMedJ-2021-0303-1 Full Text: PDF
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Over 2500 years ago Hippocrates said: “Let food be your medicine and medicine be your food”. From this position, a literature review in determining effective preventive and health-improving nutrition during the Covid-19 pandemic was carried out, measures to reduce the risk of a vulnerable viral disease using available foods with specific properties that can accelerate the recovery process and reduce various complications that accompany in case of Covid-19 disease was considered. A wide range of valuable foodstuffs, widely consumed of plant and animal origin, are presented, which to a certain extent help to get out of a serious illness without any complications, supply the human body with the necessary components that can block the spread of a viral infection and create immune resistance in the human body. Attention is paid to Chinese folk medicine, which during the Covid-19 epidemic in China played a role in the treatment of coronavirus among a wide range of people. The role of well-known vitamins in wellness and preventive nutrition in order to improve the general condition of people who survived the Covid-19 disease is shown.
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Introduction Dental caries is an infectious disease with predominantly of cariogenic bacteria such as Streptococcus mutans (S. mutans ). Xylitol is considered as one of the effective agents that can limit this dental infection. In this randomized, placebo‐controlled trial, we aimed to evaluate the potential reflection of short‐term xylitol consumption on pro‐inflammatory cytokines (TNF‐α, IL‐6 and IL‐8) and S. mutans counts by ELISA and qPCR (Quantitative real‐time PCR), respectively. Methods In this study, 154 participants were assigned to two groups, control and xylitol. Dental examination, saliva and swab samples were done at baseline and at 3‐week for clinical and microbiological assessment. Results In xylitol group at the end of 3‐week, gingival and plaque index scores were significantly decreased with respect to baseline values (p<0.001 and p<0.05, respectively). The salivary concentration of TNF‐α, IL‐6 and IL‐8 were statistically declined at 3‐week, more so than those at baseline in xylitol group (p<0.001). S. mutans expression was reduced about 5‐fold at 3‐week use of xylitol and it was a statistically significant difference compared to baseline (p<0.001). Conclusion Intriguingly, even short‐term consumption of xylitol might play a favorable role in maintaining the oral health status, possibly as a result of decreasing the release of pro‐inflammatory cytokines and the counts of S. mutans . Nonetheless, this investigation warrants further endorsement.
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Objective To provide a state of the art review of intranasal antiviral drug delivery and to discuss current applications, adverse reactions, and future considerations in the management of coronavirus disease 2019 (COVID-19). Data Sources PubMed, Embase, and Clinicaltrials.gov search engines. Review Methods A structured search of the current literature was performed of dates up to and including April 2020. Search terms were queried as related to topics of antiviral agents and intranasal applications. A series of video conferences was convened among experts in otolaryngology, infectious diseases, public health, pharmacology, and virology to review the literature and discuss relevant findings. Conclusions Intranasal drug delivery for antiviral agents has been studied for many years. Several agents have broad-spectrum antiviral activity, but they still require human safety and efficacy trials prior to implementation. Intranasal drug delivery has potential relevance for future clinical trials in the settings of disease spread prevention and treatment of SARS-CoV-2 and other viral diseases. Implications for Practice Intranasal drug delivery represents an important area of research for COVID-19 and other viral diseases. The consideration of any potential adverse reactions is paramount.
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Xylitol has been widely documented to have dental health benefits, such as reducing the risk for dental caries. Here we report on other health benefits that have been investigated for xylitol. In skin, xylitol has been reported to improve barrier function and suppress the growth of potential skin pathogens. As a non-digestible carbohydrate, xylitol enters the colon where it is fermented by members of the colonic microbiota; species of the genus Anaerostipes have been reported to ferment xylitol and produce butyrate. The most common Lactobacillus and Bifidobacterium species do not appear to be able to grow on xylitol. The non-digestible but fermentable nature of xylitol also contributes to a constipation relieving effect and improved bone mineral density. Xylitol also modulates the immune system, which, together with its antimicrobial activity contribute to a reduced respiratory tract infection, sinusitis, and otitis media risk. As a low caloric sweetener, xylitol may contribute to weight management. It has been suggested that xylitol also increases satiety, but these results are not convincing yet. The benefit of xylitol on metabolic health, in addition to the benefit of the mere replacement of sucrose, remains to be determined in humans. Additional health benefits of xylitol have thus been reported and indicate further opportunities but need to be confirmed in human studies.
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Background Coronaviruses (CoVs) primarily cause enzootic infections in birds and mammals but, in the last few decades, have shown to be capable of infecting humans as well. The outbreak of severe acute respiratory syndrome (SARS) in 2003 and, more recently, Middle-East respiratory syndrome (MERS) has demonstrated the lethality of CoVs when they cross the species barrier and infect humans. A renewed interest in coronaviral research has led to the discovery of several novel human CoVs and since then much progress has been made in understanding the CoV life cycle. The CoV envelope (E) protein is a small, integral membrane protein involved in several aspects of the virus’ life cycle, such as assembly, budding, envelope formation, and pathogenesis. Recent studies have expanded on its structural motifs and topology, its functions as an ion-channelling viroporin, and its interactions with both other CoV proteins and host cell proteins. Main body This review aims to establish the current knowledge on CoV E by highlighting the recent progress that has been made and comparing it to previous knowledge. It also compares E to other viral proteins of a similar nature to speculate the relevance of these new findings. Good progress has been made but much still remains unknown and this review has identified some gaps in the current knowledge and made suggestions for consideration in future research. Conclusions The most progress has been made on SARS-CoV E, highlighting specific structural requirements for its functions in the CoV life cycle as well as mechanisms behind its pathogenesis. Data shows that E is involved in critical aspects of the viral life cycle and that CoVs lacking E make promising vaccine candidates. The high mortality rate of certain CoVs, along with their ease of transmission, underpins the need for more research into CoV molecular biology which can aid in the production of effective anti-coronaviral agents for both human CoVs and enzootic CoVs.
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The inhibitory activities of grapefruit seed extract (GSE) on avian influenza virus (AIV), Newcastle disease virus (NDV), infectious bursal disease virus (IBDV), Salmonella Infantis (SI) and Escherichia coli (EC) were evaluated. Original GSE contained 0.24% benzalkonium chloride (BZC), however, 0.0025% BZC solution could not inactivate bacteria. The activity of diluted GSE (×100, ×500 and ×1,000 with redistilled water) against selected viruses and bacteria was evaluated in this study. The GSE solutions were incubated with the pathogens over a period of time after which the remaining viruses were titrated and the bacterial colonies were counted. In the presence of organic material—5% fetal bovine serum (FBS), the test solutions were sprayed at 1 cm and 30 cm distances to test the efficacy of GSE in a spray form. Furthermore, the efficacy of GSE against bacteria on clothes was tested using non-woven cloth. GSE×100 reduced the viral titer of both AIV and NDV even in 5% FBS condition. IBDV showed high resistance to GSE. GSE×1,000 inactivated both SI and EC within 5 sec, even in the presence of 5% FBS. The disinfectant was able to maintain its efficacy in the spray form at 30 cm distance. GSE was also effective against SI and EC inoculated on fabric. GSE is a potential novel disinfectant against viruses and bacteria, effective even within a short contact time.
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The sugar alcohol xylitol inhibits the growth of some bacterial species including Streptococcus mutans. It is used as a food additive to prevent caries. We previously showed that 1.5-4.0 g/kg body weight/day xylitol as part of a high-fat diet (HFD) improved lipid metabolism in rats. However, the effects of lower daily doses of dietary xylitol on gut microbiota and lipid metabolism are unclear. We examined the effect of 40 and 200 mg/kg body weight/day xylitol intake on gut microbiota and lipid metabolism in mice. Bacterial compositions were characterized by denaturing gradient gel electrophoresis and targeted real-time PCR. Luminal metabolites were determined by capillary electrophoresis electrospray ionization time-of-flight mass spectrometry. Plasma lipid parameters and glucose tolerance were examined. Dietary supplementation with lowor medium-dose xylitol (40 or 194 mg/kg body weight/day, respectively) significantly altered the fecal microbiota composition in mice. Relative to mice not fed xylitol, the addition of medium-dose xylitol to a regular and HFD in experimental mice reduced the abundance of fecal Bacteroidetes phylum and the genus Barnesiella, whereas the abundance of Firmicutes phylum and the genus Prevotella was increased in mice fed an HFD with medium-dose dietary xylitol. Body composition, hepatic and serum lipid parameters, oral glucose tolerance, and luminal metabolites were unaffected by xylitol consumption. In mice, 40 and 194 mg/kg body weight/day xylitol in the diet induced gradual changes in gut microbiota but not in lipid metabolism.
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Xylitol is a pentahydroxy sugar-alcohol which exists in a very low quantity in fruits and vegetables (plums, strawberries cauliflower pumpkin). On commercial scale xylitol can be produced by chemical and biotechnological processes. Chemical production is costly and extensive in purification steps. However, biotechnological method utilizes agricultural and forestry wastes which offer the possibilities of economic production of xylitol by reducing required energy. The precursor xylose is produced from agricultural biomass by chemical and enzymatic hydrolysis and can be converted to xylitol primarily by yeast strain. Hydrolysis under acidic condition is the more commonly used practice influenced by various process parameters. Various fermentation process inhibitors are produced during chemical hydrolysis that reduce xylitol production, a detoxification step is therefore necessary. Biotechnological xylitol production is an integral process of microbial species belonging to Candida genus which is influenced by various process parameters such as pH, temperature, time, nitrogen source and yeast extract level. Xylitol has application and potential for food and pharmaceutical industries. It is a functional sweetener as it has prebiotic effects which can reduce blood glucose, triglyceride and cholesterol level. This review describes recent research developments related to bio-production of xylitol from agricultural wastes, application, health and safety issues.
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To determine the tolerability of xylitol mixed with water as a nasal irrigant and to evaluate whether xylitol nasal irrigation results in symptomatic improvement of subjects with chronic rhinosinusitis. A prospective, randomized, double-blinded, controlled crossover pilot study. Twenty subjects were instructed to perform sequential 10-day courses of daily xylitol and saline irrigations in a randomized fashion, with a 3-day washout irrigation rest period at the start of each treatment arm. Collected data included patient characteristics, along with Sino-Nasal Outcome Test 20 (SNOT-20) and Visual Analog Scale (VAS) scores reported at the beginning and end of each irrigation course. Fifteen of the 20 subjects (75%) returned their SNOT-20 and VAS data for analysis. There was a significant reduction in SNOT-20 score during the xylitol phase of irrigation (mean drop of 2.43 points) as compared to the saline phase (mean increase of 3.93 points), indicating improved sinonasal symptoms (P = .0437). There was no difference in VAS scores. No patient stopped performing the irrigations owing to intolerance of the xylitol, although its sweet taste was not preferred by three subjects (21%). One patient reported transient stinging with xylitol. Xylitol in water is a well-tolerated agent for sinonasal irrigation. In the short term, xylitol irrigations result in greater improvement of symptoms of chronic rhinosinusitis as compared to saline irrigation.