Hermetica Superfood Encyclopedia
The Short Answer
Cucurbitacin B is a tetracyclic triterpenoid compound found in plants of the Cucurbitaceae family that demonstrates potent anti-cancer properties in laboratory studies. This bioactive compound works primarily by suppressing NF-κB signaling pathways and modulating MAPK/ERK cascades to inhibit tumor cell proliferation and metastasis.
CategoryNamed Bioactive Compounds
GroupCompound
Evidence LevelModerate
Primary Keywordcucurbitacin B benefits
Synergy Pairings3
Cucurbitacin B (Triterpenoid) — botanical close-up
Health Benefits
Origin & History
Natural habitat
Cucurbitacin B is a highly oxidized tetracyclic triterpenoid with molecular formula C32H46O8, naturally occurring in plants of the Cucurbitaceae family, including traditional Chinese medicinal herbs. It features a lanostane skeleton multi-substituted with hydroxy, methyl, and oxo groups, with unsaturation at positions 5 and 23, and an acetylated hydroxy at C-25.
“Cucurbitacin B is produced by plants in the Cucurbitaceae family, which comprise numerous traditional medicinal Chinese herbs. However, specific historical uses, durations, or traditional indications for isolated Cucurbitacin B are not documented in the available sources.”Traditional Medicine
Scientific Research
No human clinical trials, randomized controlled trials, or meta-analyses for Cucurbitacin B were identified in the available research. All evidence comes from preclinical studies including in vitro and animal models demonstrating anti-proliferative effects through mechanisms like NF-κB inhibition.
Preparation & Dosage
Traditional preparation
No clinically studied dosage ranges, forms, or standardization details are available as human trials have not been conducted. Consult a healthcare provider before starting any new supplement.
Nutritional Profile
Cucurbitacin B is a highly oxygenated tetracyclic triterpenoid (molecular formula C32H48O8, MW ~560.7 g/mol) found in cucurbit plants (cucumber, bitter melon, squash). It is not a conventional nutrient and provides no meaningful macronutrient or micronutrient value. As a bioactive secondary metabolite, it occurs in plant tissues at trace concentrations typically ranging from 0.001–0.1% dry weight depending on plant species and tissue type. Concentrations in cucumber fruit are extremely low (<1 mg/kg fresh weight), while roots and leaves may contain higher amounts. Bioavailability is poorly characterized in humans; limited oral bioavailability is suspected due to poor aqueous solubility (log P ~3.5, indicating moderate lipophilicity), potential first-pass metabolism, and rapid plasma clearance observed in rodent pharmacokinetic studies. It is not a source of calories, protein, carbohydrates, fats, vitamins, or minerals in any nutritionally relevant quantity. Its relevance is entirely as a bioactive phytochemical with pharmacological properties. Typical experimental in vitro and in vivo doses range from nanomolar (nM) to low micromolar (µM) concentrations. Toxicity at higher doses is a significant concern, as cucurbitacins are responsible for the bitter taste and toxic properties of certain cucurbit plants. No established Dietary Reference Intake (DRI) or safe upper intake level exists for this compound.
How It Works
Mechanism of Action
Cucurbitacin B exerts its biological effects by suppressing nuclear factor-κB (NF-κB) activation, which reduces inflammatory cytokine production and tumor cell survival signals. The compound also modulates the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway, leading to decreased cellular proliferation and increased apoptosis in cancer cells. Additionally, cucurbitacin B interferes with STAT3 signaling and disrupts actin filament organization, contributing to its anti-metastatic properties.
Clinical Evidence
Research on cucurbitacin B is primarily limited to in vitro cell culture studies and animal models, with no completed human clinical trials available. Laboratory studies have demonstrated IC50 values ranging from 0.1-10 μM against various cancer cell lines, including breast, lung, and colon cancer cells. Animal studies using doses of 1-5 mg/kg have shown tumor growth inhibition rates of 40-70% in xenograft models. However, the compound's high toxicity and lack of human safety data significantly limit its therapeutic potential and clinical translation.
Safety & Interactions
Cucurbitacin B exhibits significant cytotoxicity with narrow therapeutic windows in animal studies, causing gastrointestinal distress, hepatotoxicity, and potential bone marrow suppression at effective doses. The compound may interact with medications metabolized by cytochrome P450 enzymes, though specific drug interactions have not been well characterized. Pregnant and breastfeeding women should avoid exposure to cucurbitacin B due to its potent biological activity and lack of safety data. Currently, no standardized dosing guidelines exist for human use, and the compound is not approved for therapeutic applications.
Synergy Stack
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Frequently Asked Questions
What foods contain cucurbitacin B naturally?
Cucurbitacin B is found in bitter varieties of cucumbers, melons, gourds, and pumpkins, particularly in the stems, leaves, and roots. Wild and ornamental members of the Cucurbitaceae family typically contain higher concentrations than commercially cultivated varieties.
How effective is cucurbitacin B against cancer cells?
In laboratory studies, cucurbitacin B shows IC50 values of 0.1-10 μM against various cancer cell lines, with some studies reporting 50-80% growth inhibition. However, these effects have only been demonstrated in cell cultures and animal models, not human clinical trials.
What is the difference between cucurbitacin B and other cucurbitacins?
Cucurbitacin B differs from other cucurbitacins (A, C, D, E, I) in its specific hydroxyl and acetyl group arrangements, which affect its potency and selectivity. Cucurbitacin B generally shows stronger anti-cancer activity than cucurbitacins A and C but similar potency to cucurbitacin E.
Can cucurbitacin B be taken as a supplement?
Cucurbitacin B is not available as a commercial dietary supplement due to its high toxicity and lack of human safety data. The compound requires careful handling and is primarily used for research purposes in laboratory settings.
What are the side effects of cucurbitacin B exposure?
Animal studies indicate cucurbitacin B can cause severe gastrointestinal upset, liver damage, and bone marrow suppression at biologically active doses. Accidental ingestion of bitter cucurbitaceae plants has caused nausea, vomiting, and diarrhea in humans.
What is the current level of scientific evidence for cucurbitacin B's anti-cancer mechanisms?
Current evidence for cucurbitacin B's anti-cancer effects is primarily limited to in vitro (cell culture) and preclinical animal studies, with no completed human clinical trials published to date. While laboratory research shows promising mechanisms—including NF-κB pathway suppression, MAPK/ERK modulation, and PI3K/Akt/mTOR inhibition—these findings cannot yet be directly translated to human efficacy or safety. Any claims about cucurbitacin B as a cancer treatment would be considered preliminary and unproven without adequate human clinical data.
Does cucurbitacin B interact with chemotherapy or cancer medications?
Due to cucurbitacin B's potential effects on cellular signaling pathways (NF-κB, MAPK, PI3K/Akt/mTOR) and the absence of human clinical studies, possible interactions with chemotherapy agents cannot be ruled out. Patients undergoing cancer treatment or taking prescription medications should consult their oncologist or healthcare provider before considering any cucurbitacin B supplementation. The preclinical evidence alone is insufficient to establish a safe interaction profile with conventional therapeutic drugs.
Who should avoid cucurbitacin B supplementation?
Pregnant and nursing women should avoid cucurbitacin B due to lack of safety data in these populations and cucurbitacin's known toxicity at high doses. Individuals with active cancer or undergoing chemotherapy should not take cucurbitacin B without explicit medical supervision, as potential pathway interactions could be harmful. People with liver or kidney disease should also exercise caution, as the triterpenoid's metabolism and elimination pathways are not fully characterized in clinical populations.
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