Traditionally used for
- Mood & calm
- Blood pressure
☯ TCM Properties
Clears Summerheat, quenches thirst and remove Heat toxin
Traditional Chinese Uses
Xian Cao is the aerial parts of Mesona chinensis (Lamiaceae), the grass-jelly or "immortal grass" plant. Sweet and cold, it clears Summerheat, generates fluids to quench thirst, and resolves Heat toxicity. It is a gentle, food-grade cooling medicinal taken chiefly in the hot season for heat-stroke tendency, irritability and thirst from Summerheat, and mild Heat-toxin patterns; it is also used supportively for high blood pressure and Heat-type diabetes-like thirst in folk practice.
Most commonly the boiled, slightly oxidized stems and leaves are set with a little starch into the cooling black "grass jelly" (liang fen / xian cao dessert) eaten as a summer refreshment, or the herb is decocted as a cooling tea. Being cold, it is best avoided in those with Spleen-Stomach cold or loose stools.
Western Herbalism Properties
Relationships
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Botanical Description
Mesona chinensis Benth. (Lamiaceae), known as Xian Cao or Liang Fen Cao (grass jelly plant), is an annual herbaceous mint relative native to southern China, Taiwan, and Southeast Asia, where it is widely cultivated for both culinary jelly and medicinal use. Plants are 15-100 cm tall, with quadrangular hairy stems often tinged purple, decumbent at the base and erect above. The opposite leaves are ovate to lanceolate, 2-5 cm long, with coarsely serrate margins, an acute tip, and a pubescent dark green surface that becomes blackish on drying. Small bilabiate flowers, white to pale pink with a purple upper lip, are borne in dense terminal one-sided racemes 2-10 cm long during late summer and autumn, subtended by ovate bracts. The fruit consists of four small smooth nutlets. The dried whole herb, when boiled with starch, releases a polysaccharide gel that sets into the well-known black grass jelly; medicinally it clears summer heat, relieves thirst, cools blood, and supports treatment of mild hypertension and diabetes.
Active Constituents
Mesona chinensis polysaccharide
Acidic heteropolysaccharideConcentration: reported molecular weights spanning roughly 44 to 1450 kDa depending on extraction; one preparation gave a 29.36% yield with 16.26% uronic acid
The gelling principle of grass jelly and the constituent most of the pharmacology rests on. It is an acidic heteropolysaccharide of glucose, galactose, galacturonic and glucuronic acid, rhamnose, arabinose and xylose. Its viscosity slows gastric emptying and, with carbohydrase inhibition, blunts the glycaemic response to starchy food; antioxidant, immunomodulatory and gut-microbiota effects are reported in animals.
Rosmarinic acid
Caffeic acid depside (phenolic ester)Concentration: a principal phenolic of ethanolic extracts; content varies with growth stage and with post-harvest processing
The characteristic Lamiaceae phenolic, present here as in most mints. It is antioxidant and anti-inflammatory and contributes to the radical-scavenging capacity of the herb, and it is one of the markers whose level falls when the herb is processed by sweating rather than direct drying.
Caffeic acid
Hydroxycinnamic acidConcentration: identified in methanolic fractions alongside protocatechuic, p-hydroxybenzoic, vanillic and syringic acids
A simple phenolic acid and the biosynthetic precursor of rosmarinic acid. It contributes to antioxidant activity and, with the other benzoic and cinnamic acids of the extract, to the mild antimicrobial activity reported for the herb.
Rutin
Flavonol glycoside (quercetin 3-O-rutinoside)Concentration: reported in ethanolic extracts together with apigenin, 7-hydroxycoumarin, ferulic acid, isoquercetin, kaempferol and quercetin derivatives
One of the flavonoids of the ethanolic extract. Total flavonoid content is the fraction most affected by post-harvest handling — sweating the herb lowers it — so flavonoid-based claims about Xian Cao depend heavily on which processed form is being described.
Kaurane and atisane diterpenoids
DiterpenoidConcentration: eleven novel diterpenoids, including kaurane, atisane and sarcopetalane types, isolated from methanolic extract
A structurally distinctive minor fraction of the herb. Their pharmacology is essentially uncharacterised — they are reported as isolated structures rather than as constituents with established activity — and they are unlikely to be present in meaningful amounts in the aqueous jelly.
⚠ Drug Interactions
Insulin and oral hypoglycaemic drugs (metformin, sulfonylureas, acarbose)
In a human crossover study, co-ingesting Mesona chinensis grass jelly reduced the glycaemic response to complex carbohydrate but had no effect on the response to monosaccharide glucose — a pattern that points to inhibition of gut carbohydrase and to the physical effect of the hydrocolloid, rather than to a systemic insulin-like action. Mesona polysaccharide also improved glycaemic control, beta-cell damage and oxidative stress in type 2 diabetic mice. The mechanism overlaps directly with acarbose.
Clinical note: Xian Cao eaten as jelly with a meal is a reasonable adjunct, but a diabetic patient on insulin or a sulfonylurea who starts taking it regularly should monitor capillary glucose for the first two weeks; the effect appears only when it is taken with starchy food.
Orally administered drugs taken at the same time (narrow-therapeutic-index drugs in particular)
The active fraction is a high-molecular-weight viscous hydrocolloid, and the human glycaemic data are consistent with it slowing carbohydrate digestion and absorption in the gut lumen. Soluble viscous fibres as a class can delay the absorption of co-administered drugs, but no absorption study has been done with Mesona chinensis and any medicine.
Clinical note: No evidence of a real problem, but as with any viscous fibre it is sensible to separate a narrow-therapeutic-index drug from a large serving of grass jelly by a couple of hours.
Statins and other lipid-lowering drugs
Mesona chinensis extract lowered lipids in high-fat-diet-fed mice and rats, an effect the authors attributed to modulation of the gut microbiota rather than to HMG-CoA reductase inhibition. There are no human lipid data for the herb, so any additive effect is inferred from rodent work.
Clinical note: No action needed. If lipids fall further than expected on a stable statin dose, regular grass jelly consumption is a benign explanation to consider rather than a reason to change therapy.
Evidence Tier
Moderate evidence · 3 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
0
Randomized controlled trial
1
0 verified · 1 unverified
Other clinical trial
0
Observational / case report
0
In vitro / animal
2
0 verified · 2 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
Effects of grass jelly on glycemic control: hydrocolloids may inhibit gut carbohydrase.
A human crossover study of Mesona chinensis grass jelly co-ingested with different carbohydrate loads. Grass jelly reduced the glycaemic response to complex carbohydrate but had no effect on the response to monosaccharide glucose, which the authors read as inhibition of gut carbohydrase by the hydrocolloid rather than a systemic hypoglycaemic action. This is the only human evidence for the herb and it concerns the food form, not a concentrated extract. The article carries a publisher DOI that is not registered with Crossref, so it is cited here by its PubMed record.
Mesona chinensis Benth. Extract Ameliorates Hyperlipidemia in High-Fat Diet-Fed Mice and Rats by Regulating the Gut Microbiota
Mesona chinensis extract improved the lipid profile of high-fat-diet-fed mice and rats, with the benefit tracked to changes in gut microbial composition rather than to a direct effect on hepatic lipid synthesis. Rodent work only; it supports the traditional use of Xian Cao as a cooling summer food with metabolic benefit but does not establish a human dose or a lipid-lowering claim.
Integrating LC-MS and HS-GC-MS for the metabolite characterization of the Chinese medicinal plant Platostoma palustre under different processing methods
An analytical comparison of post-harvest processing of the herb under its accepted name Platostoma palustre. Sweating the herb promoted polysaccharide accumulation and stability and raised 51 differential metabolites, but reduced total flavonoid content, while direct drying raised amino acids and flavour compounds. Practically, this means the sweated and the sun-dried drug are not chemically interchangeable: the sweated material is the better source of the gelling polysaccharide on which the glycaemic effect depends, while the dried material retains more flavonoid.
References
- Pan J, Shi Y, Zou J, Zhang X, Xin B, Zhai B, Guo D, Sun J, Luan F. Preparation technologies, structural features, and biological activities of polysaccharides from Mesona chinensis Benth.: A review . Journal of Ethnopharmacology (2024) [DOI]
- Seah R, Siripongvutikorn S, Wichienchot S, Usawakesmanee W. Functionality and Health-Promoting Properties of Polysaccharide and Plant-Derived Substances from Mesona chinensis . Foods (2024) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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