Know Your Orchid Medications (Part 3): Getting to Know Allicin

Humankind went through a long passage of time in moving from primitive civilization to modern civilization. With the continuous advancement of science, humankind has achieved most gratifying results in preventing and treating diseases, and all kinds of antibacterial and therapeutic drugs emerge in an endless stream. As the saying goes, "Every medicine is three parts poison," and that is not at all false. Modern pharmacology is also constantly exploring new drugs that are highly effective, low in toxicity, and low in side effects, and so people have thought of green, environmentally friendly bionic drugs. Yaoyuan here introduces to everyone a plant we are relatively familiar with in daily life - garlic. In Chinese folk legend, garlic is the key substance used to ward off evil. In botany, garlic belongs to the Liliaceae family, with the scientific name Allium sativum L. Like other vegetables, it is rich in vitamins, minerals, and dietary fiber. What makes it rather different from other vegetables, however, is that it contains 17 kinds of amino acids and 33 kinds of sulfur-containing organic substances, and this is also the source of garlic's pungent odor. Allicin is a volatile oily substance extracted from the spherical bulb of garlic. It is a mixture of diallyl trisulfide, diallyl disulfide, and methyl allyl disulfide, among others; the trisulfide has a relatively strong inhibitory and killing effect on pathogenic microorganisms, and the disulfide also has a certain antibacterial and bactericidal effect. Allicin can be extracted directly from fresh garlic. About 3 kg of garlic oil can be extracted from one ton of dry garlic. Nowadays, garlic oil with diallyl trisulfide as its main component can also be chemically synthesized, with a purity greater than 98%. When garlic oil is diluted by adding a carrier and made into powder form, it can become an allicin preparation of a certain content. Allicin is a natural antibacterial substance, basically has no cumulative effect, and will not produce residues; allicin generally does not produce drug resistance either. The mechanism of action of allicin: allicin's unique molecular structure gives it a strong garlic odor. The bactericidal effect of allicin is mainly because the diallyl sulfide in it has unique physiological activity. Allyl is a conjugated structural group, and its electronegativity is relatively high, so it can partially supply electrons to the adjacent sulfur atom, reducing the electron deficiency of sulfur and increasing its activity. Therefore, after allicin is absorbed in the body, it can produce a certain amount of physiologically active sulfur-containing groups, and many sulfur-containing groups are known effective bactericides that can disrupt physiological processes such as bacterial protein synthesis. Allicin is a magical substance that is volatile, extremely foul-smelling, and has a relatively strong inhibitory ability against fungi and molds, able to keep pests, fungi, and bacteria in the soil away from garlic. As for allicin's ability to prevent and controlorchiddiseases and pests, its application arose in a casual conversation. At the time, an article said that planting some garlic or scallions in an orchid garden could inhibit the occurrence of true bacteria, so Yaoyuan planted a few cloves of garlic in the orchid garden as an environmental bacteria-repelling organism, and later a friend recommended allicin to Yaoyuan. Most of the allicin currently used on the market is a type intended for aquaculture, and this type uses starch as a carrier, accounting for about eighty-five percent or so of the allicin. Because starch is used as a carrier, allicin is not suitable for direct spraying onorchidleaf surfaces. If directly sprayed onorchidleaves, it easily causes starch to accumulate on the leaf surface, and over time the starch is very easily contaminated by true bacteria and causes trouble. Yaoyuan uses allicin as an environmental sterilizing agent. Whenever spring warmth or the moldy rainy season arrives and air humidity increases and true bacteria are produced in large numbers, after using allicin the entire orchid garden is surrounded in every possible way by the gas volatilized by the allicin; when the true bacteria smell the gas, they flee one after another or are killed, and in this way the living environment of the true bacteria can be effectively inhibited and destroyed. In addition, allicin can also be used as a pot-surface spray without spraying it onto the leaves, to shoot and kill the true bacteria on the surface of the growing medium. (Gao Haiyong)