Lipophilic phthalocyanines for their potential interest in photodynamic therapy: synthesis and photo-physical properties

Beneficial effects of a mouthwash containing an antiviral phthalocyanine derivative on the length of hospital stay for COVID-19: randomised trial

The risk of contamination and dissemination by SARS-CoV-2 has a strong link with nasal, oral and pharyngeal cavities. Recently, our research group observed the promising performance of an anionic phthalocyanine derivative (APD) used in a mouthwash protocol without photoexcitation; this protocol improved the general clinical condition of patients infected with SARS-CoV-2. The present two-arm study evaluated in vitro the antiviral activity and cytotoxicity of APD. Additionally, a triple-blind randomized controlled trial was conducted with 41 hospitalized patients who tested positive for COVID-19. All the included patients received World Health Organization standard care hospital treatment (non-intensive care) plus active mouthwash (experimental group AM/n = 20) or nonactive mouthwash (control group NAM/n = 21). The adjunct mouthwash intervention protocol used in both groups consisted one-minute gargling/rinsing / 5 times/day until hospital discharge. Groups were compared considering age, number of comorbidities, duration of symptoms prior admission and length of hospital stay (LOS). The associations between group and sex, age range, presence of comorbidities, admission to Intensive care unit (ICU) and death were also evaluated. The in vitro evaluation demonstrated that APD compound was highly effective for reduction of SARS-CoV-2 viral load in the 1.0 mg/mL (99.96%) to 0.125 mg/mL (92.65%) range without causing cytotoxicity. Regarding the clinical trial, the median LOS of the AM group was significantly shortened (4 days) compared with that of the NAM group (7 days) (p = 0.0314). Additionally, gargling/rinsing with APD was very helpful in reducing the severity of symptoms (no ICU care was needed) compared to not gargling/rinsing with APD (28.6% of the patients in the NAM group needed ICU care, and 50% of this ICU subgroup passed way, p = 0.0207). This study indicated that the mechanical action of the protocol involving mouthwash containing a compound with antiviral effects against SARS-CoV-2 may reduce the symptoms of the patients and the spread of infection. The use of APD in a mouthwash as an adjuvant the hospital COVID-19 treatment presented no contraindication and reduced the hospital stay period.

Trial registration: The clinical study was registered at REBEC—Brazilian Clinical Trial Register (RBR-58ftdj).

Methylsulfonyl Zn phthalocyanine: A polyvalent and powerful hydrophobic photosensitizer with a wide spectrum of photodynamic applications

BACKGROUND

The biomedical photodynamic principle is based on the light-induced and photosensitizer-mediated killing of unwanted or harmful cells by overproduction of reactive oxygen species. Motivated by the success of photodynamic therapy (PDT) against several types of tumors, further applications of this approach are constantly identified which require the design and synthesis of novel photosensitizers with specifically tailored properties for a particular clinical application.

METHODS

Hydrophobic photosensitizers are currently gaining attention and hence a tetramethylsulfonyl Zn(II) phthalocyanine (2) was designed with respect to the desired photoproperties. The photodynamic potential of 2 was assessed by the determination of its photophysical and photochemical properties, and by a large range of biological tests including its phototoxicity against cancer cells and Gram(+) bacteria. Unsubstituted ZnPc was used as a reference compound for comparison purposes.

RESULTS

Phthalocyanine 2 has a better oxygen generation and is more photostable than ZnPc. 2 is a polyvalent and powerful hydrophobic photosensitizer with a wide spectrum of photodynamic applications against cancer (tested on A431 cells) and for Gram(+) PDI. Against Staphylococcus aureus, a maximum photokilling efficiency of more than 6 log10 steps was induced by a 5μM concentration of 2, outperforming the 3 log10 criterion for an antimicrobial effect (according to the recommendation of the American Society for Microbiology) by more than three orders of magnitude.

CONCLUSIONS

Phthalocyanine 2 has attractive photophysical and -chemical characteristics. Initial evaluation of its application in anti-tumor PDT and PDI suggest potential for further pre-clinical and clinical development of this compound.