JUGLANDACEAE

The walnut family. This family is comprised of 6 genera and about 60 species of deciduous, monoecious trees native to Asia, Europe, North and South America. Their leaves are alternate and pinnate. The male flowers are catkins the female flowers in racemes or in small groups. The fruit is a winged nutlet or a drupe containing a nut or stone. They are grown as ornamental trees and/or for their nuts or wood.

Juglans cinerea

Butternut

Family Juglandaceae

Description

A deciduous tree growing up to about 35 m. Bark grey. Leaves, bright green, pinnate with 11–19 opposite leaflets rounded at the base and with minute clusters of downy hairs beneath. Fruit egg shaped to 7 cm long, sticky-pubescent. Nuts thick shelled with many broken ridges. Flowers April to June in North America.

Habitat and cultivation

Native to eastern North America, growing in rich woods. Not often grown elsewhere.

Parts used

Dried inner bark.

Active constituents

1) Naphthoquinones including juglone (5-hydroxy-1,4-naphthoquinone), juglandin and juglandic acid.1 Also contains essential and fixed oil, tannins and a bitter principle²

Actions

1) Laxative

2) Mild cathartic

3) Cholagogue

4) Vermifuge

5) Dermatological agent

Scientific information

All three Juglans species have much in common, more valued in the past they still have both commercial (nuts, oil) and medicinal value. J. cinerea was an official preparation in the United States Pharmacopoiea from 1820–19052 but has received very little scientific investigation as a medicinal.

In vitro—The bark has very good antimicrobial activity against:

• a range of bacteria including Staphylococcus aureus, Bacillus subtilis, Mycobacterium phlei, Pseudomonas aeruginosa, Salmonella typhimurium, Klebsiella pneumoniae
• a range of fungi including Candida albicans, Cryptococcus neoformans, Trichophyton mentagrophytes, Microsporum gypseum, Aspergillus fumigatus and Fusarium oxysporum, as well as some that have become resistant to standard antifungals^3,4

The active constituents for the antimicrobial activity are considered to be the naphthoquinones⁵ which are common to all the medicinal Juglans spp. Juglone is the best known of these. It is a strong oxidant producing hydrogen peroxide in cells, which may account for its abililty to be:-

• cytotoxic to some cell types both normal^5,6 and malignant.^7–9 Possible mechanisms are by causing DNA damage, interferring with transcription and protein synthesis and through altered potassium flow through the cell membrane¹⁰
• antibacterial—against Listeria monocytogenes, MRSA,¹¹ some cariogenic bacteria,^12,13 Bacillus subtillis, Mycobacterium smegmatis¹⁴ and Helicobacter pylori¹⁵
• antifungal—against a number of pathogenic fungi including Candida albicans, Trichophyton mentagrophytes and Microsporum gypseum¹⁴
• antiviral—inhibits the growth of HIV through inhibition of reverse transcriptase¹⁶
• antiparasitic against Toxoplasma gondii¹¹

Medicinal uses

Cardiovascular system

• haemorrhoids

Gastro-intestinal tract

J. cinerea is considered a gentle laxative and intestinal stimulant in small doses, emetic and cathartic in large doses. It does not cause griping or constipation.

• constipation (chronic)
• liver dysfunction
• dyspepsia

Skin

Through stimulation of liver and bowel function the herb is considered an alterative. Used internally and externally for cutaneous eruptions (exudative) including:-

• eczema
• herpes
• indolent ulcers

Externally

• eye inflammation
• acne

Pharmacy

Three times daily
Decoction of dried bark	–   2–6 g
Fluid Extract bark (25%)	–   2–6 ml
Fluid Extract leaves (25%)	–   0.6–2 ml
Tincture green hulls 1:10 (25%)	–   0.5–2 ml

Historical uses

Dysentery; for rheumatism and arthritis; headaches; syphilis; old ulcers (internally and externally); tonic; fevers and toothache. Used externally as a wash for wounds to stop bleeding and promote healing. The fruit oil as vermifuge for tapeworm though the bark was used for thread and pin worms.

Juglans nigra

Black walnut

Family Juglandaceae

Description

A taller tree, growing to about 50 m. Bark, dark brown, and fissured. Leaves pinnate with 15–23 leaflets, ovate oblong, slightly hairy underneath and on leaf stems, but hairs solitary, not in clusters. Fruits rounded, strongly ridges and thick shelled.

Odour—leaves aromatic, bark odourless; taste—leaves and bark are bitter and astringent.

Habitat and cultivation

Native to eastern North America, growing in rich woods. Also grown in central Europe but rarely elsewhere. Often planted for timber.

Parts used

Dried inner bark, leaves and fruit husks.

Active constituents

1) Naphthoquinones—mainly juglone,1 also plumbagin¹⁸

Also tannins including ellagic acid,¹⁹ volatile oil and flavonoids (based on myricetin and sakuranetin).²⁰

Nutritional constituents

Vitamins: B₁₂

Minerals: Manganese, magnesium, silica, calcium, phosphorus, iron and potassium

Actions

1) Alterative

2) Laxative

3) Antimicrobial

4) Vermifuge

5) Sudorific—green hulls

Scientific information

There is very little specific information available in the modern literature relating to J. nigra.

The leaf extract scavenges peroxynitrite radicals in vitro.²¹ The naphthoquinones (as for J. cinerea) are cytotoxic and inhibit the growth of malignant cells.¹⁸ Ellagic acid is also cytotoxic and anti-oxidant.²²

J. nigra has a reputation as an antifungal. For actions of juglone see J. cinerea.

Medicinal uses

Skin

Used internally and externally.

• eczema
• herpes
• indolent ulcers

External

• fungal infections
• acne

Pharmacy

Three times daily
Decoction of dried bark	–   2–6 g
Fluid Extract bark (25%)	–   2–6 ml
Fluid Extract leaves (25%)	–   0.6–2 ml
Tincture green hulls 1:10 (25%)	–   0.5–2 ml

Historical uses

Culpeper recommended the fresh leaves for digestive ailments and said the older leaves were heating and drying and harder to digest but may be better for those with a “colder stomach”, also for worms. For venomous bites or those of a mad dog; as an astringent for women's courses and falling hair; agues; plague; deafness; earache; old ulcers, scrofula and carbuncles; as a gargle for inflammations of throat and mouth.

Juglans regia

Walnut, Persian walnut

Family Juglandaceae

Description

Deciduous tree, to about 30 m with a broad spreading crown and silvery bark. Leaves pinnate with 5–9 leaflets, downy when young but becoming glabrous as they grow older. Aromatic when crushed. Male catkins pendulous, 5–15 cm appear with the young leaves. Fruit 4–5 cm, ovoid, green and glandular. Shell thin or thick and wrinkled.

Habitat and cultivation

Native to South-East Europe, and widely cultivated throughout the world for its nuts.

Parts used

Leaves, bark and the green hulls.

Active constituents23

1) Napthoquinones-mainly juglone (about 0.5%).²⁴ Juglone levels are reduced in dried leaves

2) Phenolic acids, based on cinnamic and quininc acids (these were highest in spring-early summer)

3) Flavonoids based on quercetin and kaempferol

4) Tannins based on ellagic acid²⁵

Also a number of volatile oil constituents.²⁶ The fleshly outer part of the fruit is rich in vitamin C.

Actions

1) Alterative

2) Laxative

3) Antimicrobial

4) Dermatological agent

Scientific information

J. regia is the best studied of the three species, this being reflected in the known list of constituents. They all seem to have many uses in common. The leaf has been used medicinally for thousands of years. German Commission E has approved the leaves for external use only to treat mild superficial skin inflammation and excessive perspiration of feet and hands.

In vitro—The leaves inhibit the acne-causing bacteria Propionibacterium acnes also Staphylococcus aureus and S. epidermis, the level of activity being similar to that of antibiotics.²⁷ They are also active against Helicobacter pylori.²⁸ J. regia has very good antifungal activity against a number of pathogenic fungi including Microsporum canis, Trichophyton mentagrophytes and T. violaceum.²⁹

The bark too is antimicrobial with activity against Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Pseudomonas aeruginosa and Candida albicans.³⁰ (There are ethnobotanic reports of the bark being used to “clean teeth”).³¹ It is also antiproliferative for a number of cell lines, is antimutagenic and anticarcinogenic.^32,33

Many of the parts of this species have been used in traditional systems of healing. Walnut, the edible nut itself has potential benefits for cardiovascular^34,35 and Alzheimer's disease.³⁶

For actions of juglone see J. cinerea.

Weiss suggests this herb is suitable for the treatment of skin conditions in children.

Medicinal uses

Gastro-intestinal tract

• constipation
• liver dysfunction

Skin

• eczema
• herpes
• inflammation of the eyelids

Externally

• ulcers
• cutaneous eruptions
• fungal infections
• acne

Pharmacy

Three times daily
Decoction of dried bark	–   2–6 g
Fluid Extract bark (25%)	–   2–6 ml
Fluid Extract leaves (25%)	–   4–8 ml
Tincture green hulls 1:10 (25%)	–   0.5–2 ml

Precautions and/or safety

Juglans spp. have been implicated in toxicity in animals however there are no reports in the literature of poisoning in humans. In vitro the leaf extract of J. regia was not toxic to hepatocytes37 nor was the herb found to be genotoxic,³⁸ although juglone itself is mutagenic.³⁹

There is a report of the juice of green walnut hulls (J. regia) causing acute irritant contact dermatitis, presumed to be due to juglone.^40,41

Historical uses

See J. nigra. Nuts thought to be good for the brain and therefore good for headaches and epilepsy, (doctrine of signatures); good for sexual vigour, associated with Jupiter and love.