Cornus species / Kornoeljesoorten

Japanse kornoelje / Cornus kousa Cornaceae (Kornoeljefamilie) Plantenfuncties: fruit, groentes, vers eetbaar, verwerkt eetbaar, bijenplant, meerjarig,

Bloeitijd: mei - juni

Oogsttijd: september - oktober

Cornus kousa wordt in Europa als sierplant aangeboden. De struik is inheems op Honshu in Japan, de bergen van Sichuan in China en in Korea. In de natuurlijke situatie komt de struik voor langs randen van bossen en als struikvegetatie.

Cornus kousa is een langzaam groeiende, bladverliezende struik. Na veel jaren kan de struik een hoogte van zes meter bereiken. Pas dan is de struik mooi. Wie zo'n struik wil aanschaffen, moet er rekening mee houden dat de struik even breed als hoog wordt. Plant deze kornoelje op een tegen wind beschutte plaats in de zon. De struik komt uiteindelijk als solitair het beste tot zijn recht. In het najaar heeft deze kornoelje een rozerode met groene herfstkleur.

Wat het meest opvalt aan een bloeiende struik zijn de vier stervormig geplaatste, witte gegolfde bloemomwindselbladen (bracteeën). Centraal staat de eigenlijke bloem. Bleekgroen van kleur en weinig imponerend. Wanneer de bloem bevrucht is, verkleurt deze naar fel rozerood en lijkt dan nog het meeste op een rijpe framboos. De vruchten verschijnen niet altijd. Vorming ervan is sterk afhankelijk van de hoeveelheid zonneschijn. De vruchten zijn erg lekker in kleine hoeveelheden. Ook zde jonge bladeren zijn eetbaar.

Cornus kousa Japanese Dogwood

This article originally appeared in the July 1998 edition of the Friends of PFAF newsletter.

Japanese Dogwood is a deciduous tree growing up to 10 metres tall and 6 metres wide. It is very ornamental, especially when in flower in early summer, but also when heavily laden with fruit and when it colours up in the autumn. It belongs to a genus that contains many species that produce tasty fruits, though this species is by far the nicest according to my taste-buds.

An easily grown plant, it prefers a rich well-drained loamy soil and a position that is at least partially sunny. However, it will succeed in any soil of good or moderate fertility, ranging from acid to slightly alkaline though it dislikes shallow chalky soils. It grows well in heavy clay soils. It is hardy to about -20°c and so should succeed in most parts of the country. The plant is fairly resistant to honey fungus and so can be grown in land where these fungi have killed other trees.

Plants are slow-growing when young, they speed up somewhat after a few years but then soon slow down again. The sub-species C. kousa chinensis grows more freely, flowering and fruiting better in Britain though it barely differs in appearance from the species.

The fruit, which is about 2cm in diameter, is absolutely delicious and can be eaten raw or cooked. The skin is rather tough and unpleasant with a bitter flavour, but the pulp inside has an exquisite flavour that has a hint of banana and a custard-like texture - this is far and away one of our favourite late summer fruits. We find the best way of eating it is to take a small bite out of the skin and spit this out. Then you suck out the inner flesh and just enjoy it. There are quite a few moderately sized seeds in the flesh, though we do not find that they detract in any way from the pleasure of eating this fruit.

Propagation can be a bit slow. Try to obtain fresh seed and so it immediately in a cold frame - it should then germinate in the spring. Be sure to wash all the fruit flesh off the seed since it contains germination inhibitors. Stored seed should be cold stratified for 3 - 4 months (soak it in warm water for 24 hours, then put it in a plastic bag with some compost and store it in the salad compartment of the fridge) and sown as early as possible in the year. Scarification (removing some of the woody seed case so that water can reach the seed more easily) may also help as may storing the soaked and bagged up seed for a few weeks in a warm position before the cold stratification. Germination, especially of stored seed, can be very slow often taking 18 months or more. Prick out the seedlings into individual pots as soon as they are large enough to handle and grow the plants on for their first winter in a greenhouse, planting out in the spring after the last expected frosts.

The plant can also be propagated by cuttings, though these are not as vigorous as seedlings. However, if you know of a particularly good fruiting form then cuttings are the best way of increase. Half-ripe side shoots 10 - 15cm long and preferably with a heel can be taken in July or August. Put them in a sandy compost and place them in a lightly shaded place in a greenhouse or polytunnel. It is important to keep the shoots in a fairly humid atmosphere and preferably with some bottom heat to encourage rooting. Rooting should take place within a few weeks, though we usually get quite poor results. We get a much better take with hardwood cuttings in late autumn once the leaves have fallen. These should be 15 - 20cm long of the current years growth and preferably with a heel. We put them straight into the ground in a polytunnel and usually get good results.

Cornus species monograph

Cornus controversa, Cornus kousa, Cornus macrophylla, Cornus nuttallii, Cornus officinalis, Cornus officinalis Sieb et Zucc, Cornus officinalis Sieb. et Zuce, Cornus stolonifera, Cornus stolonifera Michx, dandi tablet, dogwood fruit, red-osier dogwood, zuo-gui-wan.

Dogwood (Cornus spp.) is a deciduous tree that has showy, four-petal flowers in early spring. The indigenous peoples of the boreal forest in Canada traditionally used Cornus stolonifera for diabetes or its complications. Elders of the Saanich and Cowichan Coast Salish people of the southern Vancouver Island used Cornus nuttallii bark to treat respiratory ailments.

There is limited human evidence about the use of dogwood for use in cancer and as an antioxidant. However, future studies may investigate these areas further. Dogwood has been studied with other herbs to see its effects on hormone levels in postmenopausal and infertile women, although currently, there is a lack of strong evidence for these conditions.

SCIENTIFIC EVIDENCE

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Fertility

A traditional Chinese combination of herbs seems to have helped a woman with postmenopausal levels of follicle stimulating hormone and luteinizing hormone to become pregnant. Although this result is interesting, further research is needed in this area. C

Postmenopausal symptoms

There is currently insufficient available evidence to recommend dogwood for or against the treatment of postmenopausal symptoms. More studies are needed in this area. C

*Key to grades:

A: Strong scientific evidence for this use;

B: Good scientific evidence for this use;

C: Unclear scientific evidence for this use;

D: Fair scientific evidence against this use (it may not work);

F: Strong scientific evidence against this use (it likely does not work).

TRADITION

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious and should be evaluated by a qualified health care professional.

Antioxidant, cancer, cataracts, coronary heart disease, diabetes, diabetic complications, diabetic eye disease, diabetic microangiopathy (disease of very fine blood vessels), diabetic neuropathy (nerve damage), HIV/AIDS, hyperlipidemia (high cholesterol), respiratory ailments, sperm motility.

DOSING

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

ADULTS (OVER 18 YEARS OLD)

There is no proven safe or effective dose for dogwood in adults.

CHILDREN (UNDER 18 YEARS OLD)

There is no proven safe or effective dose for dogwood in children.

SAFETY

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

SIDE EFFECTS AND WARNINGS

Use cautiously in patients taking aldose reductase inhibitors, as dogwood may inhibit these enzymes.

Use cautiously in patients taking antineoplastic (anticancer) agents, as dogwood may have antineoplastic activity.

Use cautiously in patients with HIV, as dogwood may inhibit virus replication.

Use cautiously in patients attempting to become pregnant or who are postmenopausal, as dogwood may alter hormone levels.

Avoid in patients who are using birth control pills, as dogwood may alter hormone levels.

PREGNANCY AND BREASTFEEDING

Dogwood is not recommended in pregnant or breastfeeding women due to a lack of available scientific evidence.

Dogwood should be used cautiously with estrogens, fertility agents, and birth control pills.

Dogwood fruits may increase sperm motility.

INTERACTIONS WITH DRUGS

Dogwood may protect against diabetic complications. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare professional, including a pharmacist. Medication adjustments may be necessary.

Dogwood fruit may alter cholesterol levels in the body. Use with caution.

Dogwood may have anticancer activity. Use cautiously with anticancer agents due to possible additive effects.

Dogwood may have antioxidant activity. Use cautiously with antioxidants due to possible additive effects.

Use dogwood extracts (stem and leaf) cautiously with antiretroviral agents due to possible additive effects.

Dogwood fruit may alter hormone levels and may increase fertility in infertile women. Use cautiously with estrogen, fertility agents, and birth control pills.

AUTHOR INFORMATION

This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

REFERENCES

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

• Chang JS, Chiang LC, Hsu FF, et al. Chemoprevention against hepatocellular carcinoma of Cornus officinalis in vitro. Am J Chin Med 2004;32(5):717-725. View Abstract

• Chao SL, Huang LW, Yen HR. Pregnancy in premature ovarian failure after therapy using Chinese herbal medicine. Chang Gung Med J 2003;26(6):449-452. View Abstract

• Jeng H, Wu CM, Su SJ, et al. A substance isolated from Cornus officinalis enhances the motility of human sperm. Am J Chin Med 1997;25(3-4):301-306. View Abstract

• Kim HY, Oh JH. Screening of Korean forest plants for rat lens aldose reductase inhibition. Biosci Biotechnol Biochem 1999;63(1):184-188. View Abstract

• Liang R, Chen MR, Xu X. [Effect of dandi tablet on blood lipids and sex hormones in women of postmenopausal stage]. Zhongguo Zhong Xi Yi Jie He Za Zhi 2003;23(8):593-595. View Abstract

• McCune LM, Johns T. Antioxidant activity in medicinal plants associated with the symptoms of diabetes mellitus used by the indigenous peoples of the North American boreal forest. J Ethnopharmacol 2002;82(2-3):197-205. View Abstract

• Min BS, Kim YH, Tomiyama M, et al. Inhibitory effects of Korean plants on HIV-1 activities. Phytother Res 2001;15(6):481-486. View Abstract

• Nishino C, Kobayashi K, Fukushima M. Halleridone, a cytotoxic constituent from Cornus controversa. J Nat Prod 1988;51(6):1281-1282. View Abstract

• Renault S, Croser C, Franklin JA, et al. Effects of consolidated tailings water on red-osier dogwood (Cornus stolonifera Michx) seedlings. Environ Pollut 2001;113(1):27-33. View Abstract

• Turner NJ, Hebda RJ. Contemporary use of bark for medicine by two Salishan native elders of southeast Vancouver Island, Canada. J Ethnopharmacol 1990;29(1):59-72. View Abstract

• Xu HQ, Hao HP, Zhang X, et al. Morroniside protects cultured human umbilical vein endothelial cells from damage by high ambient glucose. Acta Pharmacol Sin 2004;25(4):412-415. View Abstract

Arch Pharm Res. 2007 Apr;30(4):402-7. Lignans from the fruits of Cornus kousa Burg. and their cytotoxic effects on human cancer cell lines.

Lee DY, Song MC, Yoo KH, Bang MH, Chung IS, Kim SH, Kim DK, Kwon BM, Jeong TS, Park MH, Baek NI. Graduate School of Biotechnology & Plant Metabolism Research Center, Kyung Hee University, Suwon, Korea.

The fruits of Cornus kousa Burg. were extracted with 80% aqueous MeOH, and the concentrated extract partitioned with EtOAc, n-BuOH and H2O. Six lignans were isolated from the EtOAc fraction through repeated silica gel, ODS and Sephadex LH-20 column chromatographies. From the physico-chemical data, including NMR, MS and IR, the chemical structures of the compounds were determined to be (+)-pinoresinol (1), (-)-balanophonin (2), (+)-laricresinol (3), erythro-guaiacylglycerol-beta-coniferyl aldehyde ether (4), threo-guaiacylglycerol-beta-coniferyl aldehyde ether (5) and dihydrodehydrodiconiferyl alcohol (6), which were isolated for the first time from this plant. Most of these compounds showed cytotoxicity against human colon carcinoma (HCT-116) and human hepatocellular carcinoma (HepG2) cell lines in vitro, with IC50 values ranging from 19.1 to 71.3 microg/mL.