Yu Mi Xu (Corn Silk or Stigma Maydis)

What Is Yu Mi Xu

Yu Mi Xu commonly known as Corn Silk or Stigma Maydis is the shiny fibers at the top of an ear of Zea mays L., which is an annual herb blonging to the family Gramineae. It is a relatively practical and common Chinese herbal medicine, which first appeared in <Dian Nan Ben Cao> (Yunnan Materia Medica) in the first year of Zhengtong in the Ming Dynasty (1,436 AD).

There are 6 species of Zea. Zea diploperennis and Zea perennis are perennial, and the other species are annual. Among them, the most famous species is Zea mays L..

Zea mays L. is also known as Maize, Corn, or Indian Corn and is an important grain. They are a staple food in many parts of the world. They are used in many fields such as food, medical and health, aquaculture, light industry, chemical industry, and so on. The total world corn production in 2021 was about 1.2 billion tonnes.

This plant is indigenous to Mesoamerica and was domesticated in Mexico some 9,000 years ago, then it spread throughout the American continents [1]. Now, it is widely grown in tropical and temperate regions all over the world.

Maize

From summer to autumn, people gather the ripe fruits of Zea mays L., take out the long fibers at the top of their ears, remove impurities, use them directly, or dry them in the sun, and make them into Chinese herbal medicines.

Yu Mi Xu contains maysin, 3′-methoxymaysin, apimaysin, ax-4″-OH-maysin, eq-4″-OH-maysin, ax-4″-OH-3′-methaxymaysin, isoorientin, 2″-O-α-L-rhamnosyl-6-C-quinovosylluteolin, 2″-O-α-L-rhamnosyl-6-C-fucosylluteolin, 2″-O-α-L-rhamnosyl-6-C-fucosyl-3′-methoxyluteolin, 2″-O-α-L-rhamnosyl-6-C-3″-deoxyglucosyl-3′-methoxyluteolin, 6,4′-dihydroxy-3′-methoxyflavone-7-O-glucosides, ax-5″-methane-3′-methoxymaysin, ax-4″-OH-3′-methoxymaysin, 7,4′-dihidroxy-3′-methoxyflavone-2″-O-α-L-rhamnosyl-6-C-fucoside, isoorientin-2-2″-O-α-L-rhamnoside, onocerin, isorhamnetin, werecis-α-terpinol, citronellol, 6,11-oxidoacor-4-ene, trans-pinocamphone, eugenol, neo-iso-3-thujanol, cis-sabinene hydrate, polysaccharides, amino acids, sterols, saponins, fats, proteins, crude fibers, and some trace elements.

Generally, the soft and shiny Yu Mi Xu is preferred.

According to <Dian Nan Ben Cao>, the medicinal property of Yu Mi Xu is relatively neutral, with a sweet taste. It has a certain therapeutic effect on the pathological changes of the bladder, liver, and gallbladder meridians.

In traditional Chinese medicine, it is often used to induce diuresis and remove edema, drain dampness and relieve jaundice, and treat edema, dysuria, scanty dark urine, difficulty and pain in micturition, gonorrhea, kidney stones, gallstones, cholecystitis, icteric hepatitis, chronic hepatitis, nephritis, cystitis, prostatitis, urinary tract infection, gout, nephrotic syndrome, diabetes, hypertension, hyperlipidemia, obesity, and metabolic syndrome. It is an important ingredient in Xiao Ke Wa and Jie Shi Tong Pian.

Benefits

  • Anti-oxidation, scavenging DPPH free radicals, ABTS free radicals, and hydroxyl free radicals.
  • Inhibiting the formation of calcium oxalate crystals and reducing joint swelling in gouty arthritis model rats.
  • Anti-depression, reducing the immobility period during force swimming tests and tail suspension tests assays in mice [2].
  • Inhibiting the activities of α-amylase and α-glucosidase and reducing blood glucose levels in diabetic mice induced by streptozotocin or alloxan.
  • Reducing serum total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels and increasing high-density lipoprotein cholesterol levels in hyperlipidemia model rats.
  • Reducing the whole blood viscosity and plasma viscosity of rats with the blood stasis model (stimulated by epinephrine and ice water), and improving the blood circulation.
  • Promoting the urine volume of saline-loaded rats and the excretion of K+ and Cl-.
  • Inducing diuresis and treating edema and dysuria.
  • Treating scanty dark urine, difficulty and pain in micturition, urolithiasis caused by damp-heat in the urinary bladder.
  • Draining dampness, and treating jaundice caused by damp-heat or cold-dampness.
  • Inhibiting the growth of H22 tumor-bearing and liver cancer HepG2 cells, and inducing apoptosis of liver cancer SMMC-7721 cells.
  • Studies have found that its crude flavonoids can prolong the swimming exhaustion time of mice, reduce the blood lactate and blood urea nitrogen concentrations, and increase the liver glycogen concentrations. This confirms that it can elevate the exercise tolerance and has anti-fatigue activity [3].
  • In the gentamicin-induced nephrotoxicity experiment, corn silk administration (200 and 300 mg/kg) with gentamicin injection significantly decreased serum creatinine levels, reduced interstitial nephritis, and ameliorated nephropathy during prolonged therapeutic use of gentamicin and related aminoglycosides [4].

Combinations

  • It can be used in combination with Ze Xie (Rhizoma Alismatis), Dong Gua Pi (Exocarpium Benincasae), and Chi Xiao Dou (Adzuki Bean) to treat edema and dysuria.
  • It can be used in combination with Bai Zhu (Rhizoma Atractylodis Macrocephalae) and Fu Ling (Poria) to treat edema caused by spleen deficiency.
  • It can be used in combination with Che Qian Cao (Plantago Asiatica) and Ye Xia Zhu (Phyllanthus Urinaria) to treat scanty dark urine, difficulty and pain in micturition caused by damp-heat in the urinary bladder.
  • It can be used in combination with Hai Jin Sha (Spora Lygodii) and Jin Qian Cao (Lysimachia Christinae) to treat urolithiasis.
  • It can be used in combination with Fu Zi (Radix Aconiti Lateralis Preparata), Gan Jiang (Dried Ginger), and Yin Chen (Capillary Wormwood) to treat jaundice caused by cold-dampness.

Side Effects

Animal experiments have confirmed that it is non-toxic in nature. There were no histopathological and adverse effects observed at a corn silk concentration of 8.0% (w/w) consumed for 90 days [5].

At present, there are no reports of serious adverse reactions caused by taking it in prescribed doses.

Precautions and Warnings

  • The dosage of Yu Mi Xu should be controlled at 15-30g.
  • When using fresh Yu Mi Xu, the dosage should be doubled.
  • It can be made into decoctions, pills, or teas.
  • People allergic to corn should not take it.
  • Pregnant and breastfeeding women should take it under the guidance of a doctor.