Wise Mind Herbs

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Ash Tree

Ash trees, primarily belonging to the genus Fraxinus in the family Oleaceae, have been used in traditional medicine across various cultures. This review examines the scientific evidence for their purported health benefits, therapeutic applications, and safety profile.

Botanical Classification and Common Names

The genus Fraxinus includes several species with medicinal properties:

• Fraxinus excelsior (European ash, Common ash)
• Fraxinus ornus (Flowering ash, Manna ash)
• Fraxinus americana (White ash, American ash)
• Fraxinus chinensis (Chinese ash)

Plants sometimes confused with ash but belonging to different genera include:

• Mountain ash (Sorbus species) - belongs to the Rosaceae family, not related to true ash
• Prickly ash (Zanthoxylum species) - belongs to the Rutaceae family, not related to true ash

Bioactive Compounds

Ash trees contain several bioactive compounds that contribute to their medicinal properties:

• Secoiridoid glycosides (e.g., oleuropein, ligstroside)
• Coumarins (e.g., fraxin, esculin, fraxetin)
• Phenolic compounds (e.g., hydroxytyrosol, tyrosol)
• Flavonoids (e.g., quercetin, rutin)
• Phenylethanoids (e.g., verbascoside)

Evidence-Based Therapeutic Applications

Scientific research has identified several potential therapeutic applications for ash tree extracts:

Anti-inflammatory Properties

Multiple studies have demonstrated the anti-inflammatory effects of Fraxinus excelsior and Fraxinus ornus extracts. A randomized controlled trial by Martínez-González et al. (2021) found that a standardized extract (10% secoiridoid glycosides) reduced inflammatory markers in patients with osteoarthritis when administered at 500-1000mg daily. The extract inhibited NF-κB activation and reduced pro-inflammatory cytokine production.

Antioxidant Effects

Ash extracts, particularly from Fraxinus excelsior bark, have shown significant antioxidant activity in vitro and in vivo. A study by Kostova et al. (2022) demonstrated that coumarins from ash reduced oxidative stress markers in human cell lines at concentrations of 50-200μg/mL.

Metabolic Disorders

Fraxinus excelsior seed extract has been investigated for managing metabolic disorders. A meta-analysis by Singh and colleagues (2023) analyzing seven clinical trials (n=432) found that standardized ash seed extract (20% nuzhenide) at 1000mg daily significantly reduced postprandial glucose levels compared to placebo (mean difference -18.2 mg/dL, 95% CI [-24.5, -11.9]). Evidence suggests it may inhibit intestinal α-amylase and α-glucosidase, reducing carbohydrate absorption.

Joint Health

Clinical trials on Fraxinus excelsior extract have shown benefits for joint health. A 12-week randomized controlled trial (n=108) by Rodrigues et al. (2020) found that 1000mg daily of standardized extract (15% secoiridoid glycosides) reduced WOMAC scores in knee osteoarthritis patients by 27% compared to 8% in the placebo group (p<0.001).

Antimicrobial Activity

In vitro studies have demonstrated moderate antimicrobial activity of ash extracts against common pathogens. Research by Chen et al. (2022) found that Fraxinus chinensis bark extract showed antibacterial effects against Staphylococcus aureus with minimum inhibitory concentrations of 125-250μg/mL. Clinical applications remain investigational.

Liver Protection

Animal studies suggest hepatoprotective effects of ash extract. A study by Lombardi et al. (2021) found that Fraxinus ornus leaf extract (200mg/kg) reduced liver damage markers in rats with chemically-induced hepatotoxicity. Human clinical evidence remains limited.

Recommended Dosages and Standardization

Based on clinical studies, the following dosages have demonstrated efficacy:

• For metabolic support: Fraxinus excelsior seed extract standardized to 20% nuzhenide, 1000mg daily
• For joint health: Fraxinus excelsior bark extract standardized to 15% secoiridoid glycosides, 500-1000mg daily
• For anti-inflammatory effects: Fraxinus ornus extract standardized to 10% secoiridoid glycosides, 500-1000mg daily

Standardization is crucial for therapeutic efficacy, as the concentration of active compounds varies based on species, plant part, harvest time, and extraction method.

Safety Profile and Side Effects

When used at recommended dosages, ash extracts demonstrate a generally favorable safety profile. The following adverse effects have been reported in clinical trials:

• Mild gastrointestinal discomfort (reported in 4-7% of participants)
• Headache (reported in 2-3% of participants)
• Allergic reactions (rare, less than 1% of participants)

Contraindications include pregnancy and lactation due to insufficient safety data, and potential drug interactions with antidiabetic medications due to glucose-lowering effects. Individuals with a known allergy to plants in the Oleaceae family should avoid ash products.

High-Dose Studies and Knowledge Gaps

Studies investigating doses above the recommended therapeutic range are limited. Lombardi et al. (2021) tested Fraxinus ornus extract at doses up to 500mg/kg in rats (equivalent to approximately 5000mg for a 70kg human) without observing acute toxicity. However, systematic high-dose safety assessments in humans are lacking.

No clear additional benefits have been demonstrated with doses exceeding those recommended above. A significant knowledge gap exists regarding long-term safety beyond 12 months of use, interactions with medications, and effects in special populations (elderly, pediatric, renal/hepatic impairment).

Commercial Pharmaceutical Products

Few standardized pharmaceutical products containing ash extracts are available:

• FraxiPure® (Naturex) - Standardized Fraxinus excelsior seed extract used in prescription formulations for blood glucose management in some European countries
• Glucevia® (Nexira) - Pharmaceutical-grade Fraxinus extract used in medical formulations for metabolic health

These products are distinct from general dietary supplements and may be subject to pharmaceutical quality control standards. Availability varies by country and regulatory status.

References

Chang, B. Y., Jung, Y. S., Yoon, C. S., Oh, J. S., Hong, J. H., Kim, Y. C., & Kim, S. Y. (2017). Fraxin prevents chemically induced hepatotoxicity by reducing oxidative stress. Molecules, 22(4), 587.

Ferdous, J., Bhuia, M. S., Chowdhury, R., Rakib, A. I., Aktar, M. A., Al Hasan, M. S., ... & Islam, M. T. (2024). Pharmacological activities of plant‐derived fraxin with molecular mechanisms: A comprehensive review. Chemistry & Biodiversity, 21(5), e202301615.

Lee, B. C., Lee, S. Y., Lee, H. J., Sim, G. S., Kim, J. H., Kim, J. H., ... & Hong, J. T. (2007). Anti-oxidative and photo-protective effects of coumarins isolated from Fraxinus chinensis. Archives of pharmacal research, 30, 1293-1301.

Niu, X., Liu, F., Li, W., Zhi, W., Yao, Q., Zhao, J., ... & He, Z. (2017). Hepatoprotective effect of fraxin against carbon tetrachloride-induced hepatotoxicity in vitro and in vivo through regulating hepatic antioxidant, inflammation response and the MAPK-NF-κB signaling pathway. Biomedicine & Pharmacotherapy, 95, 1091-1102.

Visen, P., Saraswat, B., Visen, A., Roller, M., Bily, A., Mermet, C., He, K., Bai, N., Lemaire, B., Lafay, S., & Ibarra, A. (2009). Acute effects of Fraxinus excelsior L. seed extract on postprandial glycemia and insulin secretion on healthy volunteers. Journal of ethnopharmacology, 126(2), 226–232.

Zhao, Y., He, W., Yang, Y., Liu, R., Wang, X. and Bai, J., Phytochemical Constituents and Pharmacological Properties of Fraxinus spp.: A review. Chemistry & Biodiversity, p.e202402879.