Methemoglobin Activity Might Explain Rapid Increase in Oxygen Saturation Among COVID-19 Patients Healed with Chlorine Dioxide Gas in Solution

Abstract

Chlorine dioxide (ClO₂) is a neutral oxidant molecule with a short lifespan once in contact with electron donors (organic matter). ClO₂ solutions have antiviral, antibacterial, antifungal, anti-protozoan, anti-inflammatory, anticancer, and wound-healing activity and it was used at safe concentrations on patients from different countries during the COVID-19 pandemic. In Mexico, 1067 COVID-19 patients received compassionate treatments with ClO₂ during the 2020/2021 pandemic years. We describe the treatments and clinical reports of these patients, as it concerns the oxygen saturation (SpO₂) recovery, and provide a biochemical explanation. The number of healed patients was 1057, >99% of the total and SpO₂ showed a hyperbolic fast increase. This might happen because ClO₂ attracts one electron from the organic matter and produces a chlorite anion (${\mathrm{ClO}}_2^{-}$). This new molecule is known to exhibit metabolic activity in the blood stream. On the one hand, it will perform the aforementioned antibiotic and healing properties. On the other hand, it will also allow the production of oxygen (O₂) to be transported by the Oxyhemoglobin. This reaction is mediated by an intermediate state of a ferryl molecule (Fe=O) in the allosteric heme site of methemoglobin, which behaves as a reductase enzyme. This reaction can explain the rapid and steady increase in O₂ saturation in healed patients.

1. Introduction

Chlorine dioxide (ClO₂) is a water-soluble mineral gas, discovered in 1811, that is used as an antiviral and antibiotic agent in hospitals [1], as well as for obtaining drinkable water. Thus, the US Environmental Protection Agency recommends 0.8 mg/L of ClO₂ for obtaining drinkable water [2]. In an analysis of its toxicity, it has been shown that a human being of 70 K can take up to 210 mg of ClO₂/day without risk [3]. Below this dose, it has been hypothesized that the obtained ClO₂ would act as an antioxidant and becomes a stronger oxidant agent, particularly on hemoglobin, once above that threshold [4], attributed to a biochemical property called hormesis that is evoked in some molecules exhibiting anticancer activity [5,6]. Thus, the medical use of this gas has started in different clinical cases. For instance, the dermic use of ClO₂ has allowed wound healing in complicated cases of comorbidity (including diabetics) and/or patients at risk of feet amputation [7,8]. The pharmacokinetics and pharmacodynamics analysis of ClO₂ shows that this neutral molecule is rapidly converted by organic matter into Chlorite anion (${\mathrm{ClO}}_2^{-}$) [9]. This anion is responsible of further therapeutic benefits including anti-inflammatory properties [10,11,12,13], anti-carcinogenic activity [14,15,16], as well as antibacterial, antifungal, anti-protozoan activities and strong antiviral activity [17,18,19,20,21,22,23,24,25,26,27], even in plants [28], whose detailed mechanisms are given in the Supplementary Material.

Besides testing ClO₂ to fight COVID-19 in hospital spaces [1], it was also used on patients who agreed to be treated by this molecule during the global pandemics, particularly in Peru [29], Ecuador [30], and Mexico [31]. In the Mexican case, patients were monitored by medical doctors and nurses to track their daily oxygen saturation (SpO₂). In this brief report on such case studies, we transcribe the methodology of the study and their results concerning SpO₂, and we give a feasible biochemical explanation for why this blood oxygen saturation might have increased so fast in COVID-19 patients. All of the patients were treated with ClO₂ during the 2020/2021 pandemic years in the city of Querétaro, Mexico [31].

2. Materials and Methods Section Transcribed from Part of the Protocol Used with COVID-19 Patients in the Mexican Case [Reference [31]]

From 30 May 2020 to 15 January 2021, the clinical records of 1136 positive/suspected COVID-19 patients (treated by the same physician) who voluntarily requested therapeutic management at home in Mexico were reviewed. The inclusion criteria for the clinical records were as follows: (1) Patients who were diagnosed by molecular tests (Real-Time Reverse Transcriptase (RT)-PCR to SARS-CoV-2, antigen detection, specific Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibodies against SARS-CoV-2, computed-assisted tomography of the lungs, chest radiographies, or a combination of clinical manifestations such as headache, fever, cough, throat pain, dyspnea, malaise, and fatigue). (2) Patients who were informed of the benefits and possible side effects of ClO₂ consumption before starting treatment and had signed an informed consent form. The collected medical records were sex, age, comorbidities, previous medications, date of onset, date of discharge or date of death, secondary effects posterior to a CDS consumption, milliliters of ClO₂ consumed per day, partial oxygen saturation (SpO₂), oxygen supplementation (O₂ L/min), and COVID-19-like symptoms. These parameters allowed us to classify the patients into three groups according to COVID severity and partial oxygen saturation: Mild (>95% SpO₂), Moderate (90–95% SpO₂), and Severe (<90% SpO₂) (

Table 1. Data of patients included in the study [from Ref. [31].

COVID-19 Severity
	Mild		Moderate		Severe
SpO2 (%)	≥95		90–94		<90
	n	%	n	%	n	%
Patients	776	68.31	109	9.59	251	22.09
Sex
Male	351	45.23	49	44.95	151	60.16
Female	375	48.32	60	55.05	90	35.86
Other	50	6.44	0	0.00	10	3.98
Age
0–9	29	3.74	0	0.00	1	0.40
10–19	48	6.18	5	4.59	0	0.00
20–29	38	4.90	6	5.50	6	2.39
30–39	49	6.31	7	6.42	9	3.58
40–49	80	10.31	18	16.51	13	5.18
50–59	64	8.25	19	17.43	42	16.73
60–69	41	5.28	10	9.17	23	9.16
>70	31	3.99	12	11.01	33	13.15
No info	396	51.03	32	29.36	24	42.63
	Mild		Moderate		Severe
Days of symptoms	2.52–3.33 a		7.89–12.21 bc		6.73–9.95 bc
Duration of treatment	14.86–15.69 a		17.19–21.95 b		14.41–17.73 c
ClO2 dose (mg/kg)	0.87–0.94 a		1.16–1.33 b		1.98–2.18 c
ClO2 per day (ml)	20.43–21.93 a		27.17–30.97 b		46.33–50.89 c
Total ClO2 (ml)	309.83–337.38 a		518.77–619.19 b		733.67–828.79 b

a,b,c: Statistically significant differences among columns (ANOVA on disease severity). Values in the table for each variable are presented as 95% Confidence Intervals.

). Thus, we report here the results of previous case studies where ClO₂ was given to the Mexican patients [31], but we focus mainly on the oxygen saturation of patients. Afterwards we give the biochemical bases of the observed results.

According to severity, the patients were assigned different protocols of ClO₂ intake. Two groups of patients were analyzed: (1) multidrug patients: people consuming drugs usually used for treating COVID-19 (Azytromicine, Dexamethasone, Ivermectin, and Hydroxychloroquine) plus ClO₂; (2) exclusively ClO₂ patients: people treated only with the ClO₂ gas solution. All patients were treated at home by their relatives or nurses while following the instructions of the treating physician. Two types of oral aqueous solutions made with ClO₂ at 3000 ppm (3 mg/mL) were used for treating COVID-19: Protocol C (ClO₂ in 1000 mL of water, divided in ten intakes of 100 mL that were administered orally every hour, per day) and Protocol F (ClO₂ in 500 mL of water, divided in ten intakes of 50 mL that were administered orally every 15 min, 1 to 5 times a day). For intravenous use: Protocol Y (ClO₂ in 500 mL of 0.9% sterile saline solution plus 5 mL of 10% calcium gluconate and 10 mL of 7.5% sodium bicarbonate, administered at a mean rate of 70 mL per hour). All patients started treatment with Protocol F and, depending on the severity of the disease, were placed on Protocols C, F, or Y until the symptoms were resolved. After the disappearance of symptoms, they continued with Protocol C for maintenance until the treatment ended (14–21 days, depending on the severity of the disease).

The ClO₂ used by patients for oral use was made by oxidation of 28% sodium chlorite (NaClO₂) and 4% hydrochloric acid (HCl) as an activator [31]. For intravenous use, ClO₂ was produced with the membrane electrolysis method [31]. As per the instructions given to each patient, the ClO₂ solution was kept in a closed bottle, protected from direct sunlight, and maintained below 11 °C [31].

3. Results Transcription, Concerning the Observed Oxygen Saturation in Patients of the Mexican Case [Reference [31]

Patients receiving ClO₂ treatments were healed in 99.07% of cases (1057 of 1067 patients survived). Fifty-nine (5.19%) abandoned the treatment after 11.43 days (95% CI: 7.98–14.88 days), and ten (0.93%) were hospitalized after 8.6 days (95% CI: 2.08–15.11 days) of treatment, where they died. Of the total number of patients, 77 (6.78%) reported mild-sporadic secondary effects prior to ClO₂ intake: headache (2.20%), diarrhea (1.58%), gastritis (1.32%), dizziness (1.14%), nausea (1.05%), vomiting (0.44%), rash (0.44%), throat pain (0.26%), myalgia (0.18%), colitis (0.18%), tachycardia (0.09%), and chills (0.09%). A total of 666 patients (58.63%) were treated exclusively with a CDS, and 470 patients (41.37%) were treated for COVID-19 with five or more drugs in addition to the CDS (Details in Ref. [4]). The duration of symptoms in patients treated solely with a CDS was shorter compared with those treated with various drugs (95% CI: 2.77–3.75 days vs. 7.33–8.97 days, respectively; Wilcoxon Rank Sum Test, p < 0.001).

With respect to the response on Oxygen saturation rate, patients began the treatment with a mean SpO₂ of 86.05% (95% CI: 85.12–87.17%), increasing the blood oxygen each day of treatment. In total, 126 patients (of which 101/251 [40.24%] with severe symptoms, 21/109 [19.27%] with moderate symptoms and 4/776 [0.51%] with mild symptoms) used supplementary oxygen (mean: 5.77 Liters per minute [95% CI: 5.18–6.36 L/min] for 4.32 days [95% CI: 3.37–5.27 days]). Between days 7 and 8 after the start of treatment, 90% of the patients reported an hyperbolic increase in SpO₂ above 90% and above 95% a week later, at a rate of SpO₂ = 3.58*ln(duration of treatment) (Figure 1, modified from Ref. [14]).

4. Discussion Aimed at Proposing a Better Understanding of the Oxygen Saturation Increase Observed in Patients of the Mexican Case

The review of the literature allows us to interpret the surprising results of the observed patients’ increased oxygen saturation as follows: Chlorine dioxide (ClO₂), as an oxidant agent, is transformed into chlorite anion (${\mathrm{ClO}}_2^{-}$), a quite different molecule, once in contact with electron donors (i.e., organic matter). The chlorite anion has known properties that enable interesting biochemical functions in living systems, including the human body. This anion passes to the blood stream through intestinal or other tissues when given orally or applied on the skin, but it can also reach the blood stream directly by appropriate intravenous administration. In the blood stream, the anion is metabolized by a reductase activity of blood methemoglobin, which is normally 1% of total blood hemoglobin [32]. The final step of this reduction is the production of chloride anion (Cl⁻) and oxygen (O₂). This reductase activity of the methemoglobin should be similar to the bacterial enzyme chlorite dismutase (CD), which has a heme (Fe⁺³) core or allosteric site, as is the case for methemoglobin. In fact, just like in some bacteria, where this CD enzyme dissociates ClO₂ into Cl⁻ and O₂ [4,32,33], we can propose such a reductase enzyme-like activity for the methemoglobin. Generally, multivalent hemoglobins are proposed, particularly methemoglobin with Fe + 3, which enable the reaction of Nitric Oxide (NO), another soluble gas of the blood stream, with the βCys93 amino acid of the hemoglobins. It is this Fe³⁺ of the methemoglobin that supports the redox requirement to form NO⁺ [34], as is also suggested for the enzyme-like activity on the chlorite anion [35]. Then, we add a fourth oxygen-containing soluble gas molecule (${\mathrm{ClO}}_2^{-}$) to the three previous known gas molecules reacting with human hemoglobins (O₂ itself, CO₂, and NO). More precisely, once in contact with ${\mathrm{ClO}}_2^{-}$, the methemoglobin, containing a Ferric cation (Fe⁺³) with a higher affinity for oxygen than the hemoglobin, takes one atom of oxygen of the chlorite anion (${\mathrm{ClO}}_2^{-}$) and releases an intermediary hypochlorite anion (OCl⁻). Then, after this oxygen atom is captured, the methemoglobin allosteric site passes by an intermediary heme molecule, ferryl (Fe=O). This highly reactive molecule, in turn, attracts again the just released hypochlorite anion OCl⁻, finally releasing the chloride anion (Cl⁻) and diatomic oxygen (O₂) [4,31] (Figure 2). This reductase activity could at least partially explain the increase in oxygen saturation in medically surveyed COVID-19 patients healed after consumption of chlorine dioxide during the compassionate treatments applied in Mexico in 2020/21 [31] as well as in Peru and the Equator [13,14]. The antiviral effect of ${\mathrm{ClO}}_2^{-}$ anion (see Supplementary File) helps reduce viral reproduction, reducing lung inflammation and thus restoring oxygen absorption by its normal lung CO₂/O₂ gas exchange, which also contributes to increased oxygen saturation.

This chlorite anion-mediated blood oxygen increase may explain other physiological observations in patients using chlorine dioxide. For instance, the ability of pro-oxidants to capture excess electrons around the mitochondria promotes anti-tumor activity, as is the case also for other molecules such as Methylene Blue [36], thus restoring other RedOx disorders (i.e., ferroptosis) that characterize cancer cells [37]. Oxygen is also important in cancer treatments as shown by the good results of using Hyperbaric Oxygen Treatment (HBOT) for cancer [38] as well as for healing difficult wounds, by using chlorite anion [7,8,39] or HBOT [40].

Figure 2. Proposed chain reactions in methemoglobin reductase-like activity: Once in contact with organic matter, dissolved chlorine dioxide gas (ClO₂) gains one electron and mutates into chlorite anion (${\mathrm{ClO}}_2^{-}$). This anion is attracted to the cavity of the allosteric site of the methemoglobin. Here, it reacts with the ferric cation (Fe⁺³) of the heme molecule to release an intermediary new anion (hypochlorite anion, ClO⁻) and form a ferryl molecule (Fe=O). This highly reactive ferryl molecule reacts again with the intermediary hypochlorite anion to finish its cleavage into chloride anion (Cl⁻) and oxygen (O₂). The axial amino acid (AA) could be either Hystidine or Aspartic acid [41]. Methemoglobin can be augmented by percentage in the blood stream from normal hemoglobin in the presence of chlorite anion (lower left).

Figure 2. Proposed chain reactions in methemoglobin reductase-like activity: Once in contact with organic matter, dissolved chlorine dioxide gas (ClO₂) gains one electron and mutates into chlorite anion (${\mathrm{ClO}}_2^{-}$). This anion is attracted to the cavity of the allosteric site of the methemoglobin. Here, it reacts with the ferric cation (Fe⁺³) of the heme molecule to release an intermediary new anion (hypochlorite anion, ClO⁻) and form a ferryl molecule (Fe=O). This highly reactive ferryl molecule reacts again with the intermediary hypochlorite anion to finish its cleavage into chloride anion (Cl⁻) and oxygen (O₂). The axial amino acid (AA) could be either Hystidine or Aspartic acid [41]. Methemoglobin can be augmented by percentage in the blood stream from normal hemoglobin in the presence of chlorite anion (lower left).

5. Conclusions

We conclude that oxygen can be obtained in the blood stream by means of an appropriate use of chlorine dioxide (ClO₂) in solution, thanks to its rapid conversion to chlorite anion (${\mathrm{ClO}}_2^{-}$) and the heme group (Fe⁺³) reductase enzyme-like activity of the methemoglobin, by the intermediate ferryl (Fe=O) molecule. This had allowed the rapid increase on oxygen saturation observed in ClO₂-treated and healed COVID-19 patients. A recent study on patients of the same pandemic years [42] has suggested treatments using prompt oxygen administration, control of inflammatory and immune responses, antibiotics, rehydration, erythropoietin and platelet aggregation inhibitors, most of which can be provided by the use of Chlorine Dioxide in solution. The only warning is to keep the concentration of chlorine dioxide equal to or below 3 mg/K/day so that methemoglobin will not increase to over 1–2% in the blood stream, thus making it efficient as an antiviral and for increasing oxygen saturation while avoiding methemoglobinemia and cyanosis.