Blackstonia perfoliata (L.) Hudson (Yellow Wort)

2015

Blackstonia perfoliata (L.) Hudson (Chlora perfoliata L., Gentiana perfoliata L., Seguiera perfoliata O. Kuntze) of the family Gentianaceae, is called yellow wort or, yellow centaury from the color of its flowers. The genus Blackstonia is associated with the name of the author (J. Blackstone 1737), who described this plant in England. Zeltner distinguished four species in the genus Blackstonia. Tutin in Flora Europaea mentioned only one species with four subspecies: perfoliata, serotina () Vollmann, imperfoliata (L. fil.) Franco and Rocha, and grandiflora (Viv.) Maire in Jahandiez and Maire. The former two have the chromosome number 2n = 40, the others 2n = 20. The Flora of Switzerland () includes two species, B. perfoliata and B. acuminata () Domin (B. serotina, Chlora serotina). These authors reported the chromosome number 2n = 44 in B. perfoliata from England and northern France. Blackstonia perfoliata is an annual, 10-60-cm-high, erect and glaucous herb, ending in a dichasium with triangular leaves, sometimes narrowing towards the base. The yellow corolla of flowers and the linear or lanceolate calyx are divided into 6-12 lobes. The size and the lobe number represent the only differences between the subspecies. The blooming period of the plant is from June to September or from April to August.

B. perfoliata is a thermophilous plant originally found around the Mediterranean Basin. Its limit extends to Turkey and Iran in the east and to Belgium, Holland, and Ireland in the northwest. According to Fournier and Hegi, the dried aboveground parts of B. perfoliata have been described as a possible substitute for Centaurii Herba — a bitter remedy for treatment of complaints of the digestive system (e.g., dispepsia, anorexia), acting by stimulation of gastric secretion and a general tonic effect. Herb of B. perfoliata may contain up to 3% of gentiopicroside — a bitter active principle present in Centauri Herba and also in Radix Gentianae (remedia amara). Hence, it is a valuable bitter remedy more easily accessible than roots of the genus Gentiana, which are suitable for therapeutical uses only after several years of vegetation. In the 16th century, B. perfoliata was cultivated as Centaurium flore luteo. This plant is often used in medicine in place of Radix Gentianae.

The biologically active secoiridoid glucoside, gentiopicroside (gentiopicrin), was isolated from entire plants of B. perfoliata (). The amount of this compound which can occur in the plant is about 3%, and there are also small amounts of swertiamarin and sweroside. A product of the decomposition of gentiopicroside and swertiamarin, called gentiogenal, or gentiopicral, has also been found.

Blackstonia perfoliata is not present in the Polish flora. The tissue cultures were initiated using seeds obtained from sites in Greece. Seeds were kept for 14 days at 4 °C. Next, they were transferred to Petri dishes, covered with distilled water, and left to imbibe for 48h at a temperature of about 25 °C. The seeds were sterilized first with 70% ethanol, then with 0.1% sublimate (3 min) and washed three times with sterile distilled water.

Summary and Conclusions

The callus culture and micropropagation of Blackstonia perfoliata was established. This species has not been the subject of in vitro studies. The seedlings were obtained from seeds placed on half-strength MS medium without plant growth substances, as well as on MS medium supplemented with GA3 and kinetin. The callus culture was initiated from the hypocotyl on MS medium with kinetin and NAA or BAP and IAA. The best conditions for this tissue to undergo differentiation were MS medium with NAA and AS. A yellowish green callus culture was obtained when the primary callus was placed on MS medium with kinetin and 2,4-D. Micropropagation was also carried out and the regenerated plantlets grew to flowering. The suspension culture was obtained from callus tissue in liquid MS medium with kinetin and 2,4-D.

The presence of secoiridoids and flavonoids in materials from the in vitro culture was tested using TLC methods. It can now be concluded that the two groups of compounds were synthesized in the vitro culture of B. perfoliata. In the tissue culture and also in the mother plant of B. perfoliata, gentiopicroside is the dominant compound alongside small amounts of sweroside and swertiamarin. The last two secoiridoids can be treated as precursors of gentiopicroside, according to the suggestion of Inouye (1970) for the biosynthetic pathway: loganin (or loganic acid) → secologanin → sweroside → swertiamarin → gentiopicroside.

Quantitative determinations of gentiopicroside were carried out on the obtained material using the densitometric TLC method. It was found that 4-16 μg concentrations of gentiopicroside cause a linear increase in background fluorescence decay under the cited conditions. The synthesis of gentiopicroside started already in the callus tissues, increasing in rooted plantlets.

The aerial parts of B. perfoliata are of medicinal significance and through in vitro cultures the plants can be propagated to obtain the raw material.

Selections from the book: “Medicinal and Aromatic Plants IX” (1996).