2023 Activity Report vol.1:University of Toyama

Activity Report of Open Application Program 2023 vol.1 (Course B)

Exploring anti−AspH inhibitory activity in natural resources from Cameroon with the aim of developing tumor−specific anti−cancer drugs

Report from the Institute of Natural Medicine, University of Toyama

 Through the Sakura Science Program, two graduate students and one young faculty member from the Faculty of Sciences, University of Dschang in Cameroon came to Japan from June 1 to June 20, 2023, together with an Associate Professor from the same university who acted as the supervising faculty member. This program aimed to obtain compounds derived from natural resources in Cameroon that demonstrate specific inhibitor activity against the cancer−specific enzyme AspH, which is deeply involved in cancer growth, etc. It also aimed for researchers from Cameroon to participate in international joint research with the goal of developing AspH inhibitors, being carried out by the people running this program and ASEAN researchers.

 On the first day, June 1, the participants arrived in Toyama and went directly to the Natural Products Chemistry Lab in the Institute of Natural Medicine, where the program was held. They have stored fractions and extracts of plants brought from Cameroon in the laboratory and after that, attended an explanation on the equipment and devices to be used the following days. The participants were excited to prepare some reagents and book some equipment to be used in the next days, since uses of those machines have been greatly limited in Cameroon.

Activity Report Photo 1
Arriving at the Institute of Natural Medicine

 On the next day, June 2, the participants joined a meeting about the experiments for this project, then engaged in carrying out the biological assay of the fractions and crude extracts of the plants they brought from Cameroon. They were able to confirm activity in the crude extracts from several plants, although those were weak. Therefore, they started purifying continuously compounds from these samples every day from early in the morning until late at night, and till their last day. The invited researchers had never used HPLC equipment in Cameroon, so they were excited when they used it here, and ended up delighted when the purity of the compounds improved as they repeated the HPLC operation. In parallel, the researchers were also separated compounds from the fractions and the mixtures of compounds, in which later one has been partially purified before they came to Japan. This included some samples that were not able to purify into a single compound in Cameroon, even they tried the best to purify before coming in Japan. As a result, they were able to separate a mixture of three compounds by using HPLC, making them very satisfied.

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Experiment on AspH inhibitory activity of crude extracts
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Top left: Collecting partially pured compounds
Top right: purifying compounds using HPLC
Bottom left: Analyzing compounds contained in crude extract
Bottom right: Removal of solvent from sample using rotary evaporator

 The researchers checked the purity and masses of the purified compounds by using LC−MS, which combines HPLC and mass spectrometry. To determine the chemical structures, they carried out measurements of NMR spectra, which enabled the researchers to obtain more detailed information. LC−MS and NMR equipment are particularly expensive, and using them made a particularly deep impression on the invited researchers. They carried out NMR spectra measurements when the compounds were purified, and have been obtain a good spectra data on their compounds before returning to Cameroon. A new compound was also obtained through this program, which weas the greatest result during this program. The researchers are expected to report this outcome in an international academic journal after preparing more detailed data. However, while they did estimate the chemical structure based on the data from the spectra analysis, it takes time to obtain this data, so they were not able to obtain complete spectra data for the compounds obtained while they were in Japan. From now on, the people running the program will continue with this in the lab, and the remaining challenge for the future is to consider ways for the researchers to effectively obtain different spectra data.

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Analysis using LC−MS
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Organizing the pure compounds

 On June 19, the researchers carried out AspH inhibitory assay of the compounds they had obtained. Unfortunately, there was no activity in any of the compounds investigated at this time. They were not able to measure the activity in the remaining isolated compounds during the program, and it was decided that researcher members of the lab would investigate this after the program has finished. The supervising faculty member also gave a report on the outcomes of their research on the same day.

 On the final day, June 20, the participants finished up their experiments and handed over samples to the program organizers to continue measuring their activity even the program has finished. They then each received a certificate of attendance from Professor Morita at the completion ceremony. In the survey, all of the researchers said that they were extremely satisfied with this visit to Japan. We are sincerely grateful to the Sakura Science Program for giving us the opportunity to carry out this highly significant international exchange.

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At the completion ceremony