Lonicera japonica (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

Lonicera japonica Thunb. ex Murray

Protologue: Syst. Veg. ed. 14: 261 (1784).

Family: Caprifoliaceae

Chromosome number: 2n= 18

Synonyms

• Lonicera chinensis Watson (1825),
• Lonicera repens Zipp. ex Hassk. (1844).

Vernacular names

• Japanese honey-suckle (En).
• Chèvre-feuille du Japon (Fr)
• Thailand: saai nam phueng
• Vietnam: kim ngân, nhẫn dông.

Origin and geographic distribution

L. japonica originates from Japan, Korea, China, Taiwan and northern Vietnam, but is widely cultivated as an ornamental in South-East Asia up to 1000 m altitude.

Uses

In traditional Vietnamese medicine the flowers are considered diuretic, cooling, depurative and detoxicant. They are prescribed in cutaneous diseases, eczema, measles, boils, carbuncles, and especially in enteritis and dysentery. The leaf-bearing stem is credited with antibacterial and anti-allergic properties. It is recommended in the treatment of boils, impetigo, urticaria, allergic rhinitis, fever, malaria, erythema, measles, diarrhoea, dysentery, syphilis, rheumatism and prickly heat. The drug is taken in the form of a decoction, infusion, extract or alcoholic macerate. In Vietnam, L. dasystyla Rehder is used similarly. In traditional Thai medicine a decoction of the fresh stem is used as a diuretic, antipyretic, antidiarrhoeal and antidysenteric; it is used in the treatment of enterocolitis. Although sometimes considered a noxious weed in northern America, L. japonica has become an important browse plant for deer in autumn and winter. Several Lonicera species (including L. japonica) are widely grown as ornamentals for their colourful, fragrant flowers.

Production and international trade

Despite its long-standing use in South-East Asia and its omnipresence in traditional Chinese pharmacies as testimony of the trade from more temperate areas to tropical regions, no information is available on trade statistics for L. japonica.

Properties

The n-butanol fraction of whole plants of L. japonica (collected from Korea) was evaluated for its anti-inflammatory activity using several experimental animal models. At oral doses of 100-400 mg/kg, the fraction showed anti-inflammatory activity against acute, granulomatic and chronic inflammation models in mice and rats. Although the activity was not potent compared with prednisolone, these results supported the traditional use of this plant in folk medicine. These results were confirmed using an n-butanol fraction from the aerial parts of L. japonica consisting of a mixture of flavanoids, iridoids and triterpenoid saponins. By using acute models (croton oil- or arachidonic acid- induced mouse ear oedema test) or chronic models (adjuvant induced arthritis in rats) of inflammation together with activity-guided isolation procedures, loniceroside A (a hederagenin-saponin), lonicerin (a neohesperidoside flavone) and loganin (an iridoid) were identified as active compounds.

Furthermore, in a screening for phospholipase A₂ (PLA₂) inhibitors of natural origin in order to secure new anti-inflammatory agents, 2 biflavonoids have been isolated from the aerial parts of L. japonica which showed strong PLA₂ inhibition in vitro. Their structures were identified as ochnaflavone and its 4'-O-methylether. Ochnaflavone also inhibited rat platelet phospholipase A₂ at an IC₅₀ value of about 3 μM. The inhibitory activity was specific against group II phospholipases rather than group I phospholipases. Addition of excess calcium did not antagonize the inhibitory activity, indicating that the inhibition may result from direct interaction with the enzyme.

The butanol fraction of L. japonica aerial parts reduced antigen-induced contractions of isolated trachea preparations from sensitized guinea-pigs in a concentration-dependent manner. The butanol fraction also inhibited histamine release from rat peritoneal mast cells induced by antigen or calcium ionophore A23187 (IC₅₀ values of 0.26 and 0.32 mg/ml, respectively) in vitro. Eosinophil infiltration into bronchoalveolar lavage fluids induced by aero-allergen challenge in passively sensitized guinea-pigs was inhibited by the butanol fraction at a dose of 800 mg/kg (51.7%). In addition, the butanol fraction inhibited leukotriene B4 production in rat basophilic leukaemia cells (IC₅₀ of 0.42 mg/ml) as well as phosphodiesterase 4 (PDE4) isolated from rat brain (IC₅₀ of 0.015 mg/ml). At this stage, as a model, the butanol fraction of L. japonica may therefore be useful in the treatment of experimental asthma and its mode of action may be related to inhibition of both 5-lipoxygenase and PDE4 enzymes.

An extract of L. japonica flowers tested in an experimental model of chronic hepatitis B infection (using the PLC/PRF/5 cell line) suppressed hepatitis B virus surface antigen (HBsAg) secretion without cytotoxicity. The effects on blood pressure of phenolic compounds obtained from dried flowers were investigated in a spontaneously hypertensive rat model. Protocatechuic and methyl caffeate were identified as the major active substances. Chlorogenic acid and five caffeoylquinic acids at higher doses possessed the delay hypotensive effect. Also, at the highest effective dose, all of the compounds also produced hypotension in normotensive rats.

The methanolic extract of L. japonica flowers showed no anti-inflammatory activity as measured by its inhibitory effect on interleukin-8 induction in lipopolysaccharide-activated rat macrophages. A saponin fraction extracted from the flower buds showed no skin toxicity in guinea-pigs and suppressed UV-induced erythema in guinea-pigs in a dose-dependent manner.

Aqua-acupuncture is a form of acupuncture that involves the hypodermic injection of e.g. herbal extracts at acupuncture points, purportedly to stimulate them by pressure from the injected substance. L. japonica flowers aqua-acupuncture solution (LFAS) and L. japonica flowers water-extracted solution (LFWS) were prepared and tested for their chemopreventive potential. Three biomarkers, quinone reductase (QR), ornithine decarboxylase (ODC), and glutathione (GSH), were used to test the chemopreventive potential of LFAS. LFAS was a potent inducer of QR activity in Hepa1c1c7 murine hepatoma cells, whereas LFWS was less potent. LFAS and LFWS also induced QR activities in cultured human hepatoma Hep3B cells. The effects of LFAS and LFWS were also tested on the growth of Acanthamoeba castellanii. Proliferation of A. castellanii was inhibited by LFAS and LFWS at concentrations of 0.1x, 0.5x, 1x, and 3x the reference. In addition, GSH levels were increased by about 2-fold with LFAS and 1.5-fold with LFWS in cultured murine Hepa1c1c7 cells. LFAS and LFWS were also shown to increase GSH levels in human Hep3B cells. These results suggest that LFAS has chemopreventive potential by inducing QR activity, inhibiting ODC activity and increasing GSH levels.

Description

• An evergreen or semi-evergreen, vigorous, scandent shrub or climber up to 3 m tall; branches terete, hollow, glandular, prominently patent pubescent when young.
• Leaves opposite, simple, entire, ovate-oblong to ovate-lanceolate, 3-8.5 cm × 1.5-4 cm, base rounded to truncate, apex acute or subacuminate, midrib and edges pilose, dark green and shiny above; petiole about 1 cm long; stipules absent.
• Inflorescence an axillary, 2(-3)-flowered cyme, peduncle 2.5-15 mm long, each pair of flowers subtended by 2 leafy bracts, 10-18 mm × 4-8 mm, and 4 elliptical bracteoles, about 1 mm long, hairy, glandular, ciliate.
• Flowers intensely fragrant; calyx tube ovoid, glabrous, lobes ciliate; corolla bilabiate, 4-5 cm long, white turning pinkish, fading orange yellow, tube narrow, about 2.5 cm long, soft pubescent outside; stamens 5, exserted, filaments inserted near the apex of the tube; ovary inferior, 2-3-celled, 3-8 ovules per cell, style simple, as long as the corolla, stigma capitate.
• Fruit a globular berry, 6-7 mm in diameter, few-seeded, black when ripe.

Growth and development

In Vietnam L. japonica flowers from March-May, whereas in Java it flowers throughout the year. Flowers open at dusk thereby favouring nocturnal pollinators such as hawkmoths, over diurnal pollinators such as bees. L. japonica produces large quantities of seed in more temperate regions, however, in tropical South-East Asia, seed set/fruiting is rather poor. The seeds are disseminated by birds, mammals, and floodwaters. Once established, it reproduces vegetatively by rooting from the nodes of runners.

Other botanical information

L. japonica has long been a popular ornamental. L. japonica var. repens (Siebold) Rehder started its career in the Bogor Botanical garden. Some other well-known cultivars include "Aureo-reticulata", a compact shrub with golden reticulate venation, var. repens "Dart’s World" with an overall maroon-reddish appearance, "Halliana", with deeply divided corolla lobes, "Hall’s Prolific", a vigorous climber with up to 6 m long stems, " Purpurea" , with leaves tinged purple, and "Variegata", with variegated yellow leaves.

The flowers of the Eurasian L. periclymenum L. are used as a cutaneous and mucous tonic and vulnerary, the leaves in decoction are used for diseases of liver and spleen, and the seeds as a diuretic.

Ecology

L. japonica can be found in all stages of forest succession. In more temperate areas it will quickly invade following clear cutting, fire, windthrow, or temporary openings in the forest canopy. L. japonica is shade-tolerant and will respond to more favourable light conditions with greatly increased growth, dominating the area in a relatively short time. It grows well on clay soils, with a pH ranging from 6.0 to 7.5. Growth is best on well-drained forest soils. In the United States it is highly tolerant of adverse sites and grown successfully on mine spoils.

Propagation and planting

L. japonica can be easily propagated by seed, stem cuttings and layering. Plants can also be regenerated from leaf and stem calluses. For propagation by seed, stratification for 3 months at 4 °C is required.

Husbandry

L. japonica can be grown as ground cover or on trellis. Left alone it will become more and more bushy, with the inside of the bush containing only dried stems, so severely pruning the old stems is therefore recommended.

Diseases and pests

L. japonica is susceptible to honeysuckle latent carlavirus and tobacco leaf curl bigeminivirus.

Harvesting

The leafy stem parts of L. japonica are collected whenever the need arises. The flowers are preferably collected when barely open and still white.

Handling after harvest

The flowers or leafy stems of L. japonica are dried either partly screened from sun light or gently heated at low temperatures.

Genetic resources and breeding

Although largely cultivated as an ornamental and occasionally escaping in South-East Asia, L. japonica has a large area of distribution, naturally and as a result of cultivation and naturalization. It is locally considered a harmful weed and does not seem to be at risk of genetic erosion. There are no known breeding programmes of L. japonica for medicinal purposes.

Prospects

L. japonica may have some local therapeutic or cosmetic value formulated as cream, lotion or emulsion to be used topically for skin affections, since several compounds extracted from this plant revealed antimicrobial, anti-inflammatory and anti-aging activities without a skin-irritating effect. The anti-inflammatory effects of several compounds isolated from the n-butanol fraction merit further research in order to evaluate their potential as lead compounds in the development of future medicine.

Literature

• Chang, H.W., Baek, S.H., Chung, K.W., Son, K.H., Kim, H.P., & Kang, S.S., 1994. Inactivation of phospholipase A-2 by naturally occurring biflavonoid, ochnaflavone. Biochemical and Biophysical Research Communications 205(1): 843-849.
• Kern, J.H. & van Steenis, C.G.G.J., 1951. Caprifoliaceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 4. Noordhoff-Kolff, Djakarta, Indonesia. pp. 175-194.
• Kim, J.W., Choi, H.K., Shon, Y.H., Lim, J.K., Lee, H.W. & Nam, K.S., 1999. Chemopreventive potential of Lonicerae flos aqua-acupuncture solution. Korean Journal of Pharmacognosy 30(3): 261-268. (in Korean)
• Lee, S.J., Shin, E.J., Son, K.H., Chang, H.W., Kang, S.S. & Kim, H.Y., 1995. Anti-inflammatory activity of the major constituents of Lonicera japonica. Archives of Pharmacal Research (Seoul) 18(2): 133-135.
• Lee, S.J., Son, K.H., Chang, H.W., Kang, S.S. & Kim, H.P., 1998. Antiinflammatory activity of Lonicera japonica. Phytotherapy Research 12(6): 445-447.
• Ryu, K.H., Han, C.K., Rhee, H.I., Kim, T.S., Jung, I.H., Lee, S.J., Im, G.J., Lee, K.J., Joung, K.W., Kim, D.K., Kim, K.H. & Cho, Y.B., 1999. Anti-asthmatic activities of the extract of Lonicera japonica. Korean Journal of Pharmacognosy 30(4): 377-383. (in Korean)

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Authors

• Wongsatit Chuakul, Noppamas Soonthornchareonnon, Orawan Ruangsomboon