Confirmation of inactivation of COVID-19 by Craft Onsen

In May 2021, with the cooperation of a research group at Gunma University Development & Innovation, we confirmed for the first time in the world the inactivation of a COVID-19 by Craft Onsen*. In addition, by experimentally clarifying the conditions for inactivation, we have academically demonstrated its practicality.

Disinfection to prevent the spread of infection is aimed at “sterilization”, such as alcohol and hypochlorous acid, and the safety and toxicity of these methods have not been discussed. As a means of solving this problem, we conducted an experiment to inactivate the COVID-19 using Craft Onsen, which has both health-promoting and disinfecting properties. We reported that the new coronavirus was inactivated by Onsen components and that the relationship between the concentration of Craft Onsen and the inactivation was experimentally clarified. The following is a report of our experiments.

About Craft Onsen®

Craft Onsen®, a patented technology, is the world’s first hot spring purified by artisans from natural hot spring. Natural hot spring water is brought to a dedicated workshop, where the ore from the volcanic layer called hot spring shale is finely ground, put into a high-pressure pot, and carefully dripped through a high-density filter to dissolve only the hot spring components. Our craftsmen, who are well versed in the quality of hot springs, faithfully refine even the miscellaneous flavors of hot springs from various regions, resulting in a concentrated hot spring with a concentration thousands to ten thousand times higher than that of natural hot springs.

Three types of samples: Craft Onsen diluted 2500 and 5000 times, and tap water as reference.
Virus: New human coronavirus (SARS-CoV-2 WK-521) Virus titer (undiluted): 3.6×104 TCID50 / mL Cells: Vero cells (strain number: JCRB0111, medium composition: 10% serum (FBS) DMEM) Test description: Mix the virus solution with the specimen, and collect the virus solution 1 minute later. After 1 minute, the viral solution was collected and used to infect the cells to determine the amount of infectious virus.

From the results of this study, it was confirmed that the virus infection titer of Craft Onsen diluted 2500 times was reduced to less than 1/10 after 1 minute. Since no decrease in virus was observed in the reference, the evaluation index of the inactivation ability of Craft Onsen diluted 2500 times was about 92% at 1 minute. The evaluation index of the inactivation ability of Craft Onsen diluted 5000 times was about 78% in one minute.

Cytotoxicity test
In order to confirm that the test samples are not toxic to cells, the following cytotoxicity evaluation (MTT assay) was conducted. The results showed that there was no significant decrease in the absorbance values of the Craft Onsen diluted 2500 times and 5000 times compared to the absorbance values of cells exposed to serum-free DMEM medium that had not been exposed to the specimens.

・The inactivation rate of Craft Onsen reached more than 90% in one minute even when it was diluted over 2000 times.
・The correlation between the inactivation rate and the dilution concentration and test time was confirmed.
・It was confirmed that the infectivity of the COVID-19 added to Craft Onsen to cells was greatly reduced.
・It was confirmed that Craft Onsen did not show toxicity to cells.

Future development
Now that the effectiveness of Craft Onsen in inactivating the COVID-19 has been confirmed, we will continue to conduct more detailed research and propose the use of Craft Onsen as an effective means of hygiene measures in cooperation with source owners worldwide.
*Note that the results of this experiment do not mean that the use of Kraft hot springs will prevent or cure infectious diseases.


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