Dynamics of Polyphenol Biosynthesis by Calli Cultures, Suspension Cultures and Wild Specimens of the Medicinal Plant Ligaria cuneifolia (Ruiz & Pav.) Tiegh. (Loranthaceae). Analysis of Their Biological Activity

Abstract

Ligaria cuneifolia (R. et P.) Tiegh. (Loranthaceae) is a South American hemiparasitic species with antioxidant, antitumoral, antimicrobial, and antilipidemic activities attributed to its polyphenolic content. We studied the polyphenolic pattern of L. cuneifolia during different phenological stages: flowering, fruiting, and post-fruiting. The highest total phenolic content was found in stems at post-fruiting (214 ± 12.1 mg gallic acid eq·g−1 DW) and fruiting (209 ± 13.7 mg gallic acid eq·g−1 DW), followed by post-fruiting leaves (207 ± 17.5 mg gallic acid eq·g−1 DW). Flavonoids accumulated at higher levels in leaves and hydroxycinnamic acids in leaves at flowering and post-fruiting. The polyphenolic pattern was similar between organs from wild plants and in vitro cultures, although at a significantly lower level in the latter ones. The performance of calli growing under a 16 h photoperiod in a modified White medium with 1-naphthalene acetic acid (2.50 μM) and Kinetin (9.20 μM) was better than in the dark. When calli grew in media only with auxins (IAA, NAA, and 2,4-D, all at 2.50 µM concentration), its growth and polyphenolic content improved. Cell suspensions with 2.50 µM NAA and 9.20 µM KIN grew slowly and produced very small amounts of polyphenols. As for the antioxidant activity, it was detected in all samples (approximately 1000 µmol trolox eq·g−1 DW) except fruits, where a lower value was found (328 µmol trolox eq·g−1 DW). In vitro cultures have the lowest antioxidant activity when compared to methanolic extracts from organs of wild specimens. Finally, antimutagenic or mutagenic activity in wild plants and in vitro culture extracts was not detected by the Ames test.

The Argentine MistletoesLigaria cuneifolia(Ruiz & Pav.) Tiegh (Loranthaceae) andPhoradendron liga(Gillies ex Hook. & Arn.) Eichler (Santalaceae). Thirty Years of Research

“…[55,56] Betulin and betulinic acid are also obtained from the aerial parts by a dichloromethane extraction directly [57] or by maceration with ethanol followed by vacuum liquid chromatography on silica gel and elution with a stepwise gradient of hexane/diethyl ether/methanol. [58] Tyramine is also found in L. cuneifolia aerial parts, and this is particularly important since this species is mainly used as a hypotensive agent. An extensive study performed in Argentina, in the provinces of Córdoba, Mendoza, San Juan, Catamarca, Salta and Entre Ríos on 12 different hosts (belonging to the Zygophyllaceae, Anacardiaceae, Fabaceae, Mimosaceae, Santalaceae families) confirmed that specimens developing on Geoffroea decorticans contain higher levels of this substance in the stems (120-360 mg/ 100 g dried material) while leaf content is more variable (40-240 mg/100 g).…”

“…[55,56] When studying organs (stems, leaves and fruits) and phenological stages (flowering, fruiting, post-fruiting), it was verified that stems and leaves exhibit the highest polyphenolic values, especially in the fruiting and post-fruiting stage, which supports the traditional use of these organs. [55,56,58] Efforts have been directed to establish in vitro L. cuneifolia cultures. In this sense, polyphenol profile is quite similar to the adult plant, with quantitative variations.…”

“…Quercetin-glycosides, catechin and chlorogenic acid are present but not quercetin-galloyl-glycosides. [57,58] Interestingly, Soberón et al [59] studied the aerial parts of L. cuneifolia from Tucuman, in the Argentinian Northwest. A methanolic extract was subjected to further purification and among the identified compounds, two flavonol-di-glycosides were reported, rutin (quercetin-3-O-rutinoside) and nicotiflorin (kaempferol-3-O-rutinoside).…”

“…In this regard, L. cuneifolia in vitro cultures are being studied to determine the appropriate conditions for their development. [57,58] This appears as an environmentally friendly strategy to preserve wild specimens and could also provide a uniform batch-to-batch plant material produced under controlled conditions for formulation manufacturing. After 30 years of research, L. cuneifolia and P. liga still hold a great potential to be unfolded.…”

“…Betulin and betulinic acid are also obtained from the aerial parts by a dichloromethane extraction directly [57] or by maceration with ethanol followed by vacuum liquid chromatography on silica gel and elution with a stepwise gradient of hexane/diethyl ether/methanol [58] …”