Macleaya spp.

2015

The genus Macleaya belongs to the family Papaveraceae Juss. (Jussieu 1789), subfamily Papaveroideae, tribe Chelidonieae Reichb. (Reichenbach 1837). As early as 1826, the genus Macleaya was separated from the genus Bocconia L. by Robert Brown. It includes two closely related species Macleaya cordata (Willd.) R. Br. (= Bocconia cordata Willd.) native to Central to Eastern China and Central Japan, and Macleaya microcarpa (Maxim.) Fedde (= Bocconia microcarpa Maxim.) which originated from the regions of Central China, Kansu and North Shensi. M. cordata is an ornamental plant up to 3 m high and carrying splendid foliage. In 1795 it was introduced by G. Staunton into Middle European gardens. Common names for M. cordata are Federmohn (German), plume poppy or tree celandine (English), takenigusa or champagiku (Japanese), for M. microcarpa makleya melkoplodnaya (Russian).

In 1971 a report was published on experiments to culture M. cordata in.an experimental garden.

Like all other members of the tribe Chelidonieae, Macleaya also possesses laticifers containing coloured latex in which alkaloids have been found. Table Alkaloids detected in plants and cell cultures in the genus Macleaya lists these alkaloids together with those detected in callus and cell suspension cultures. Strictly speaking Macleaya is not officinal, but because of its ability to form alkaloids, some of them might be of importance in medical practice, therefore, it could be counted as a plant of medical interest. For instance, the pharmacological properties of berberine influencing cardiac activities resemble those of hydrastine; it is relatively little toxic. In addition, berberine produces a strong antibacterial and bacteriostatic effect. In this respect, however, it is surpassed by coptisine. Allocryptopine has a local anaesthetic effect even stronger than that of procaine. Also a certain antitumorous effect has been observed. Small doses of protopine retard heart activity, decrease blood pressure, and have a sedative effect. Larger doses produce excitation and convulsions. This substance also develops a strong bactericidal effect. Chelerythrine causes a temporary increase in blood pressure and releases the pain-relieving action of morphine. Sanguinarine has been incorporated into expectorant mixtures; furthermore, it has a strong bactericidal effect on Gram-positive bacteria.

Table Alkaloids detected in plants and cell cultures in the genus Macleaya

Alkaloid type Macleaya cordata Macleaya microcarpa
Plant Callus Plant Callus and cell suspension
Protopine + + + + + +
- Allocryptopine + + + + + +
- Allocryptopine + + +
Chelerythrine + - + +
Sanguinarine + + + + + +
Oxysanguinarine + + + +
Chelirubine + + +
Chelilutine + - - -
Norsanguinarine ( + ) + + - -
Macarpine + - +
Coptisine + - +
Berberine + - +
Corysamine + - - -
Dihydrosanguinarine - + -
Total alkaloid contents (%)
in root 1.54 1.23
in herbage 0.33 0.6
+ + = Major alkaloid, + = Minor alkaloid, (+) = Traces only.

The genus Macleaya has become one of the most interesting subjects in the field of plant cell culture, both for biodevelopmental questions and, especially during the last 10 years, for problems of secondary metabolism. Both aspects have been reviewed in this chapter. The most relevant published papers concerning callus and cell suspension cultures of Macleaya species are listed in Table Summary of the in vitro studies in the genus Macleaya.

Table Summary of the in vitro studies in the genus Macleaya

Macleaya cordata

  • Division of isolated mesophyll cells
  • Callus growth and plant regeneration; alkaloid contents in callus tissues and plant regenerants
  • Alkaloid formation
  • “Alkaloid cells” and alkaloid storage
  • Detection and distribution of “alkaloid cells”
  • Alkaloid transport and distribution
  • Formation of “alkaloid cells” in mesophyll protoplast-derived cell cultures

Macleaya microcarpa

  • “Alkaloid cells” and alkaloid contents in callus cultures
  • Enzymological investigations on alkaloid biosynthetic pathways
  • Shoot regeneration from and embryoid formation in long-term callus cultures
  • Alkaloid metabolism in callus and cell suspension cultures
  • Formation of “alkaloid cells” in mesophyll protoplast-derived cell cultures
  • Alkaloid contents of cell suspension cultures
  • Macleaya cordata x Macleaya microcarpa hybrid
  • Division of isolated mesophyll cells
  • Cell differentiation in isolated and cultured mesophyll cells
  • Adventitious embryo formation in callus cultures
  • Division of isolated mesophyll cells in mesophyll cell-derived callus cultures
  • Histological differentiation patterns in mesophyll cell-derived callus cultures
  • Root regeneration in callus cultures
  • Adventitious embryo formation in callus cultures

Macleaya spp.: Summary and Concluding Remarks

In this post, cell and callus cultures of the two species of the genus Macleaya (M. cordata and M. microcarpa) have been shown to be very interesting and promising subjects in morphological, developmental and biochemical investigations. Callus and cell suspension cultures in short-term and long-term modes have been established and shoot regeneration as well as formation of adventitious embryos were successful that could be raised into mature plants. The production of alkaloids including protopine, α- and β-allocryptopine, sanguinarine, oxysanguinarine, chelirubine, norsanguinarine and dihydrosanguinarine in callus and cell suspension cultures was demonstrated. Extended biochemical experiments on the conversion of reticuline into scoulerine were performed and a proposal has been made to replace the name “reticuline-converting enzyme” by the term “berberine bridge enzyme”. Despite the recent great interest in more economical plant subjects for studies of developmental and biochemical processes, the relevance of the genus Macleaya to reveal fundamental events in plant science should also not be disregarded in the future.

 

Selections from the book: “Medicinal and Aromatic Plants II”, 1989.