Chu Shi Zi
StarBroussonetia papyrifera (L.) Vent.
Traditionally used for
- Dizziness
- Eye health
- Ears & hearing
- Digestion
- Urinary & fluids
☯ TCM Properties
Nourishes Liver and Kidney Yin; Clears Liver Heat and Brightens the Eyes; Promotes Urination and Reduces Edema; Strengthens the Sinews and Bones
Traditional Chinese Uses
Chu Shi Zi (paper mulberry fruit) is a gentle, sweet, cool herb that nourishes Kidney and Liver Yin and brightens the eyes. It is used for Kidney-Liver Yin deficiency with premature greying, blurred vision, dizziness, and tinnitus. Its moistening Yin-nourishing properties are gentle and food-safe, making it appropriate for elderly patients or those with sensitive digestion who need sustained Yin supplementation. It is frequently combined with other Kidney and Liver tonics in formulas for age-related deficiency patterns.
Relationships
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Botanical Description
Broussonetia papyrifera, the paper mulberry, is a fast-growing deciduous tree of the family Moraceae, native to East Asia and widely naturalized, often invasively, across the Pacific and southeastern North America. It reaches 10 to 15 meters with smooth gray bark and abundant milky sap. The leaves are notably variable, even on the same plant, ranging from simple ovate-cordate with serrate margins to deeply two- or three-lobed, all rough above and softly pubescent beneath. The species is dioecious; male trees bear pendulous catkins and female trees produce globose, bright orange to red compound infructescences 2 to 3 cm across in summer, composed of numerous fleshy, protruding individual drupelets with conspicuous styles. These soft, sweet fruits, harvested when fully ripe, are the medicinal Chu Shi Zi.
Active Constituents
Linoleic acid
Polyunsaturated fatty acid (omega-6)Concentration: 52.58% of total fatty acids in the fruit, within a crude fat content of 20.51% of fruit dry weight; total unsaturated fatty acids 70.6%
The single most abundant characterised compound in the fruit, which is a genuinely oily drug rather than a watery berry. Oleic acid contributes 16.92% and palmitic acid 16.36% of the fatty acids. Practically, a fat content of a fifth of dry weight means the fruit goes rancid, so storage condition matters more for Chu Shi Zi than for a starchy or fibrous drug.
Total phenolics of the fruit
Phenolic compounds (mixed)Concentration: 5.79 plus or minus 0.12 mg gallic acid equivalents per gram in the aqueous extract and 3.79 plus or minus 0.03 mg/g in the ethanol extract
Modest by comparison with the root bark. In vitro, the ethanol extract scavenged 87.17% of DPPH radicals at 5 mg/mL against 58.11% for the aqueous extract, while the aqueous extract was the better iron chelator at 77.51% against 48.26%; both inhibited lipid peroxidation more than tocopherol or ascorbic acid over 168 hours at equivalent concentration.
7-Hydroxycoumarin (umbelliferone), protocatechuic acid and epicatechin
Simple coumarin and phenolic acids and flavan-3-olConcentration: the phenolic components identified by HPLC in both aqueous and ethanol fruit extracts; ferulic acid was found only in the ethanol extract
These are the phenolics actually identified in the fruit, as opposed to the prenylated flavonoids that dominate the literature on this species but come from other organs. Note that 7-hydroxycoumarin is a simple coumarin, not a furanocoumarin, so it carries no phototoxicity implication.
Prenylated flavonoids (broussochalcone A, broussonins A and B, kazinols, uralenol)
Prenylated flavonoids and diphenylpropanesConcentration: the characteristic class of the species, with more than one hundred flavonoids reported; concentrated in the ROOT BARK, branches and leaves rather than in the fruit
This is the point at which most writing about Broussonetia papyrifera stops being about Chu Shi Zi. The prenylated flavonoids behind the species' tyrosinase-inhibiting, skin-lightening, anti-inflammatory, PTP1B-inhibiting, anti-cholinesterase and antiplatelet reputation were isolated from root bark (Chu Bai Pi), branches and leaves. Most prenylated flavonoids from the root bark show moderate anti-inflammatory activity in LPS-stimulated RAW 264.7 cells via downregulation of COX-2 at 10 to 25 micromolar. None of this can be assumed to apply to the fruit, whose own characterised composition is dominated by fixed oil, minerals and simple phenolics.
Fruit polysaccharides
PolysaccharidesA water-soluble fraction extracted from the fruit specifically, reported to have antioxidant and antibacterial activity in vitro. This is one of the few activity reports genuinely conducted on the fruit rather than on another part of the plant.
Mineral fraction (calcium, potassium, phosphorus, magnesium, iron)
Inorganic mineralsConcentration: calcium 17,338.9 mg/kg, potassium 9,098.7 mg/kg, phosphorus 4,644.2 mg/kg, magnesium 3,284.6 mg/kg and iron 414.8 mg/kg of fruit dry weight; ash 9.74%
An unusually mineral-dense fruit, with vitamin E at 7.29 mg per 100 g. The same avid mineral uptake is the reason the manganese contamination question below is not hypothetical.
⚠ Drug Interactions
Manganese burden from fruit harvested on mine-contaminated or phytoremediation land
Broussonetia papyrifera is deliberately planted as a pioneer species on heavy-metal-contaminated ground and manganese mine sites, because it tolerates conditions little else does. The problem for a medicinal fruit is what that tolerance costs. Transcriptomic work on B. papyrifera fruit under manganese stress reports that manganese accumulation in fruit grown on contaminated soils exceeds safe consumption thresholds for livestock, creating a food-chain contamination risk, and that excess manganese suppresses the plant's own flavonoid biosynthesis genes. So the same fruit is simultaneously more contaminated and less phytochemically potent when grown on such land. This is a sourcing hazard, not a pharmacological interaction, but it belongs in a clinical record because the species' role in mine reclamation makes contaminated material genuinely available.
Clinical note: Buy Chu Shi Zi from suppliers who can state the growing region and who test for heavy metals, and do not accept fruit collected from reclamation plantings, mine spoil or roadside invasive stands. The risk concerns prolonged daily use rather than a short course, and it is greatest in patients with impaired hepatobiliary manganese elimination or existing parkinsonism.
Paper mulberry pollen sensitisation in patients with allergic rhinitis or asthma
Recorded because the species-level fact is striking and practitioners in affected regions will meet it. Broussonetia papyrifera is an invasive tree in Islamabad and one of the two dominant pollens behind seasonal allergy there, releasing up to around 40,000 pollen grains per cubic metre in a single peak day in March and April, and its pollen is described as among the most clinically relevant aeroallergens studied. An observational study examined whether pollen concentration tracks asthma exacerbations, against a background of increased attendance at clinics and emergency departments during the pollen season. Whether oral administration of the fruit provokes a reaction in a patient sensitised to that pollen is unstudied; pollen-food syndromes are well recognised in other taxa but have not been demonstrated here, so this is flagged as an open question rather than a known cross-reaction.
Clinical note: Ask a patient with spring-seasonal rhinitis or asthma from an affected region whether paper mulberry is their known trigger. If so, introduce Chu Shi Zi cautiously and outside the pollen season rather than assuming there is no relationship, and stop it if oral or pharyngeal symptoms follow a dose.
Insulin and oral glucose-lowering drugs
Broussonetia papyrifera extracts inhibit alpha-glucosidase, and the prenylated flavonoids uralenol and broussochalcone A inhibit the protein tyrosine phosphatase PTP1B, a negative regulator of insulin signalling. The important qualification is the plant part: these activities were characterised in extracts and compounds from root bark, branches and leaves, not from the fruit, and the fruit's own phenolic content is modest. No animal or human glycaemic study of Chu Shi Zi was found.
Clinical note: No monitoring change is warranted on this evidence. If a patient on insulin or a sulfonylurea is taking a whole-plant Broussonetia preparation rather than the fruit alone, the theoretical basis is stronger and worth a glucose check.
Chu Bai Pi (Broussonetia papyrifera root bark) and Chu Ye (leaf) as different drugs from the same plant
Not a toxicity issue but the main reason a monograph on this herb can go wrong. Broussonetia papyrifera yields several distinct traditional drugs: the fruit (Chu Shi Zi), the root bark (Chu Bai Pi), the leaf and the latex, each with its own indications. The prenylated flavonoid chemistry and the anti-inflammatory, tyrosinase-inhibiting and enzyme-inhibiting pharmacology that fill the review literature belong overwhelmingly to the root bark and branches. A supplier or a secondary source that cites that pharmacology in support of the fruit is misattributing it.
Clinical note: Confirm you are receiving the dried fruit, not bark or mixed plant material, and discount any claim for Chu Shi Zi whose supporting study used root bark. The fruit's own evidence base is compositional and in vitro.
Dosage
| Form | Amount | Frequency | Duration | Population | Notes |
|---|---|---|---|---|---|
| decoction | 6–12 g | Daily | — | — | 中国药典 2020 【用法与用量】6～12g。 【性味与归经】甘，寒。归肝、肾经。 — Chinese Pharmacopoeia 2020, quoted verbatim; route and cautions preserved. Replaces a cleared category-filler value. |
Evidence Tier
Moderate evidence · 4 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
0
Other clinical trial
0
Observational / case report
2
1 verified · 1 unverified
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
Chemical Composition and Antioxidant Activities of Broussonetia papyrifera Fruits
The reference compositional study of the fruit itself. On a dry-weight basis the fruit was 36.09% carbohydrate, 20.51% crude fat, 15.71% crude protein, 14.20% crude fibre and 9.74% ash. Linoleic acid made up 52.58% of the fatty acids, oleic 16.92% and palmitic 16.36%, with total unsaturated fatty acids at 70.6%; essential amino acids were 40.60% of total amino acids. Minerals were high, calcium at 17,338.9 mg/kg and potassium at 9,098.7 mg/kg, with vitamin E at 7.29 mg per 100 g. Total phenolics were 5.79 plus or minus 0.12 mg gallic acid equivalents per gram in the aqueous extract and 3.79 plus or minus 0.03 mg/g in the ethanol extract, with 7-hydroxycoumarin, protocatechuic acid and epicatechin identified in both and ferulic acid only in the ethanol extract. At 5 mg/mL the ethanol extract scavenged 87.17 plus or minus 0.18% of DPPH radicals against 58.11 plus or minus 0.11% for the aqueous extract, while the aqueous extract chelated iron better (77.51% against 48.26%); both outperformed tocopherol and ascorbic acid on lipid peroxidation inhibition at 168 hours. All in vitro.
Transcriptomic Analysis of Broussonetia papyrifera Fruit Under Manganese Stress and Mining of Flavonoid Synthesis Genes
A plant-science paper with a direct safety implication for this drug. B. papyrifera is confirmed as a pioneer species for heavy-metal-contaminated ground and is used on manganese mining sites for ecological restoration, but the authors report that manganese accumulation in fruit from contaminated soils surpasses safe consumption thresholds for livestock, making the fruit a food-chain contamination route. Under excessive manganese stress the fruit's flavonoid biosynthesis genes were suppressed, so contaminated material is also phytochemically weaker. Taken together this argues for provenance control on Chu Shi Zi rather than for any change in dosing.
Association of asthma exacerbations with paper mulberry (Broussenetia papyrifera) pollen in Islamabad: An observational study
Observational study of the relationship between airborne paper mulberry pollen concentration and asthma exacerbations in Islamabad, where the invasive tree is one of the two dominant seasonal allergens and pollen peaks around 40,000 grains per cubic metre in March and April. The context the authors set out is that the pollen's role in allergic rhinitis is established while its association with asthma exacerbation had not been demonstrated, despite consistently increased clinic and emergency department attendance during the pollen season. Relevant to this record as species-level allergen evidence; it says nothing about oral use of the fruit.
Assessment of the health impact of paper mulberry (Broussonetia papyrifera L.), an invasive plant species in Islamabad, Pakistan
Geospatial assessment of pollen allergy risk from the invasive paper mulberry population of Islamabad, mapping the health burden associated with the species' spread. It documents that this is a public-health-scale aeroallergen problem rather than an incidental sensitivity, which is the context for treating pollen sensitisation as a real consideration when prescribing any part of the plant to a patient from an affected region.
⚠ Safety & Contraindications
Contraindications
Its use is cautious in patients with deficiency-cold of the spleen and stomach.
Source: Xi S, Gong Y. Essentials of Chinese Materia Medica and Medical Formulas. Academic Press/Elsevier, 2017, pp. 368–376.
Historical Texts
Ben Cao Gang Mu
Ming dynasty (1596)References
- Chen Yueru; Wang Lu; Liu Xue; Wang Fulin; An Ying; Zhao Wei; Tian Jinli; Kong Degang; Zhang Wenru; Xu Yang; Ba Yahui; Zhou Honglei. The Genus Broussonetia: An Updated Review of Phytochemistry, Pharmacology and Applications . Molecules (2022) [DOI]
- Wang Guo-Wei; Huang Bao-Kang; Qin Lu-Ping. The Genus Broussonetia: A Review of its Phytochemistry and Pharmacology . Phytotherapy Research (2011) [DOI]
- Han Qiaohong; Wu Zili; Huang Bo; Sun Liangqi; Ding Chunbang; Yuan Shu; Zhang Zhongwei; Chen Yanger; Hu Chao; Zhou Lijun; Liu Jing; Huang Yan. Extraction, antioxidant and antibacterial activities of Broussonetia papyrifera fruits polysaccharides . International Journal of Biological Macromolecules (2016) [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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