Drug Discovery and Ochiai Germination Method
Why is DAIZ, a soybean business, making drugs?
The Ochiai Germination Method enables us to turn soybeans’ metabolic system into a mega-factory of extremely useful molecules.
In this method, we use a proprietary germination promoter box. We carefully control the temperature and the amounts of oxygen, carbon dioxide and moisture to create a stressful environment for the soybeans that are in the process of germinating. This stress stimulates the seeds’ development, propelling the production of daidzein – a naturally occurring isoflavone found only in soybeans.
In addition to this environmental stress, we are also studying the effects of immune stress and how it induces the productions of defensive chemicals in the plant. We use so-called “elicitors” to create immune stress. The elicitors we use are substances that are proven safe, such as tempeh bacteria, lactic acid bacteria and yeast strains.
The primary stimuli, or the environmental stimuli, can cause "hypermetabolism," while the second stimulus, or immune stress, is for "dysmetabolism.” These primary and secondary stimuli kick the soybeans’ genetics into high gear, causing enzymatic activities to ramp up. A tremendous amount of metabolites result from it. These metabolites all have a daidzein skeleton, but otherwise widely varying characteristics. It is also of note that these metabolites are small molecules that have hydrophobic groups, such as prenyl groups.
We are collaborating with the Graduate School of Agriculture of Kyoto University to take measurements of these metabolites through metabolome analysis. The team from Kyoto University uses an LC-OrbiTrap (analyzer) to measure weight up to three decimal places. We have so far discovered 30,000 different metabolites, which are secondary metabolites called phytoalexins.
While we plan to conduct analysis of each of these 30,000 metabolites to understand their functionalities, at least one metabolite has already proven to have inhibitory effects on cancer. The preliminary tests conducted by the Cancer Research Foundation showed that glyceollins (I-V) inhibited the growth of breast cancer cells to which the daidzein metabolite was added.
What is Phytoalexin? And why is it important in DAIZ’s drug discovery?
Phytoalexins are compounds with a low molecular weight that plants produce when external stress activates certain genes to promote enzyme activities, speeding up biosynthesis. Well-known phytochemicals include isoflavones in soybeans, polyphenols in grapes, lycopene in tomatoes, and catechins in tea. An antimicrobial substance, phytoalexins have strong physiological effects. Little research has been done on the potential use of phytoalexins for drug discovery, however, because it is extremely difficult to collect the substance from plants using today’s technology.
But all that can change, how that we have discovered an easy way to make plants produce phytoalexins! Our patented technology, which focuses on the plants’ amazing immune response capabilities, enables us lead the world in the mass-production of a wide variety of phytoalexins. Phytoalexins found in plants have molecular structures that are suitable for small molecule drug discovery, and we believe we will be successful in a series of seed compounds for drug discovery.
DAIZ has also made an important discovery about a substance called glyceollin, which was published in Nature's sister publication, “Scientific Reports.”
That's right. In a joint study between us and the Cancer Institute of the Japanese Foundation for Cancer Research, we were conducting an "evaluation of the growth inhibition of recurrent breast cancer cells" of “glyceollin derivatives* extracted from sprouted soybeans stressed by the Ochiai germination method. As Dr. Noriko Saito of the Cancer Institute and her colleagues were investigating the effects of glyceollin on recurrent breast cancer cells (LTED) to which glyceollin I was added and cultured, they found that it inhibited the proliferation of the cancer cells, leading to cell death. The study was published in Nature's sister publication, Scientific Report.
It has been shown that LTED cells are vulnerable to cell death induced by low molecular weight compounds with similar molecular weight and specific structure to female hormones, and one of the molecular mechanisms has been elucidated. Thus, glyceollin I is expected to have potential as a new treatment for recurrent breast cancer that is resistant to hormone therapy.
※Derivatives of Daidzein
Glyceollin I, Glyceollin II, Glyceollin III, Glyceollin IV, Glyceollin V, Glyceollin VI, Prenyl Daidzein
What are the advantages of using natural compounds in drug discovery?
Around 2000, the industry began routinely conducting high-throughput screening (HTS) of synthetic compound libraries. HTS is a rapid automated testing of a massive number of samples for drug discovery. Thanks to the advancement in IT-driven combinatorial synthesis technology, robotics and supercomputers, exploring synthetic compounds became much easier. In some science journals, people even claimed that medical and pharmaceutical people were no longer needed to develop new drugs; the West Coast, namely Silicon Valley, were going to replace the East Coast as the new epicenter of drug discovery.
But this “new era” of drug discovery didn’t last long. As it turned out, synthesized compounds and derivatives were not as diverse in their structures as initially hoped. Since then, people have grown more aware of the unlimited potential that natural compounds have as drugs.
For example, an alkaloidal anti-cancer drug called Taxol was derived from the yew plant, and the drug now has an annual sales of more than 300 billion yen.
Taxol has a very unique and complex structure that could not be easily replicated using synthetic technology. Plant leaves are good source of useful compounds, and there are many excellent cancer drugs that are derived from leaves.
Now, we discovered a way to extract even more compounds from seeds than from leaves. In fact, our technology turns seeds into a mega-factory of novel compounds that are amazingly diverse in their structures. We have successfully developed a cultivation method that works on soybeans to create almost any compound structure we want. This cultivation method, the Ochiai High Pressure Method, is named after the inventor – that is me (laughter). We have a patent on the method. (Patent number 5795676)
So, what is your next step? What’s your vision for the future?
The next step is studying the efficacy of thousands of phytoalexins extracted from isoflavones (daidzein). I think these phytoalexins may have effects that are useful in the field of epigenomics, such as histone modification. We hope to produce an encompassing variety of phytoalexins from soybeans, including terpenoids, steroids, alkaloids and lipids as well as flavonoids.
The Ochiai Germination Method enables us to make any plant seed to produce as many as 30,000 novel compounds. We used the state-of-the-art LC-OrbiTrap to take precise molecular weight measurements of these compounds. In addition, we have already successfully identified the chemical elements that comprise each of these compounds. We are now working with an AI mathematician from Massachusetts Institute of Technology (MIT) to understand the three-dimensional structure of each compound based on the information about the chemical elements. We are optimistic that we will be able to solve these difficult puzzles before long to discover new drugs from soybeans.