Seasonal variations of triterpene acid contents in Viscum album L. on typical host trees of Hyrcanian forests.

Viscum album L. (mistletoe) is a semiparasitic plant of the Santalaceae family. A valuable group of bioactive compounds in mistletoe are triterpene acids (TTAs), which possess anti-inflammatory and anticancer properties. Parrotia persica and Carpinus betulus are the most common hosts of mistletoe in the Hyrcanian forests of Iran. This study was performed to compare the content of oleanolic acid (OA), betulinic acid (BA), and ursolic acid (UA) in the mistletoe foliage (stems and leaves) from P. persica and C. betulus in various seasons for the first time. The results showed that OA was the prevailing TTA in all samples, while UA was found in none of them. The maximum amount of OA (12.38 mg/g dry weight [DW]) and BA (1.68 mg/g DW) was detected in V. album from P. persica in summer. The minimum amount of OA (5.58 mg/g DW) and BA (0.72 mg/g DW) was observed in that growing on C. betulus in winter. However, the mistletoe from C. betulus showed the greatest level of OA in spring (9.06 mg/g DW) and BA in summer and autumn (0.92 and 0.97 mg/g DW, respectively). The data collected in this study complement existing research on this subject from around the world.

Viscotoxin and lectin content in foliage and fruit of Viscum album L. on the main host trees of Hyrcanian forests.

Mistletoe (Viscum album L.) is a hemiparasitic plant that absorbs water and nutrients from the host tree. Mistletoe contains two groups of cytotoxic, immunomodulatory and antitumor proteins, viscotoxins and lectins. This study evaluated the quantity and quality of viscotoxins and total lectins in the stems with leaves (foliage) and fruit of mistletoe on Parrotia persica and Carpinus betulus in September with immature green berries and in December with mature white berries. Viscum album L. plants were harvested from host species located in the Hyrcanian forests of Iran in 2019. The highest level of viscotoxins was detected in the December foliage of V. album settled on C. betulus (9.25 mg/g dry weight [DW]), and the highest content of lectins was found in the December foliage of V. album settled on P. persica (0.79 mg/g DW) and C. betulus (0.73 mg/g DW) respectively. The immature green berries of V. album from both host species contained much higher concentrations of viscotoxins and lectins than the mature white berries. Four isoforms of viscotoxins, viscotoxin A1, A2, A3 and B could be identified in all samples of both host species. Viscotoxin A3 was the predominant viscotoxin isoform followed by viscotoxin A1.

Methyl-ß-cyclodextrin and coronatine as new elicitors of tropane alkaloid biosynthesis in Atropa acuminata and Atropa belladonna hairy root cultures.

Hyoscyamine (HYO) and scopolamine (SCO) are tropane alkaloids acting as anticholinergic factors on the parasympathetic nervous system in humans and are produced by Solanaceous plants. Two strains of Agrobacterium rhizogenes, A4 and LBA9402, were used to infect Atropa acuminata Royle ex Miers and Atropa belladonna L. leaf explants. A. acuminata was inoculated either by direct infection or sonicated-assisted A. rhizogenes-mediated transformation (SAAT) was performed. A. belladonna was inoculated with the A4 strain using a direct method. The selected hairy root lines of both species were elicited with 50 mM methyl-ß-cyclodextrin (ß-CD), 0.5 µM coronatine (Cor) or 50 mM ß-CD + 0.5 µM Cor on Day 14 of culture. The elicitor effect on growth and HYO and SCO content was analyzed after one (T1) and two (T2) weeks of treatment. In A. acuminata explants, the highest transformation percentage (T%) was obtained with strain A4 and the SAAT method (T%: 96.43). Cor significantly reduced the growth of A. acuminata hairy roots (fresh weight and dry weight [DW]: 2.52 and 0.3 g, respectively), whereas ß-CD increased their DW (0.4 g). Also, the combined ß-CD + Cor treatment had a positive significant effect on the DW of A. belladonna hairy roots (0.41 g). In A. acuminata hairy roots, the HYO level was lower under Cor treatment than in the control at both sampling times. In contrast, the SCO content was increased 10-fold by Cor elicitation at T1 compared to the control (10.95 mg g-1 DW) and was also positively affected by ß-CD + Cor. In A. belladonna hairy roots, all the elicitors had a negative effect on both HYO and SCO production. This report is the first assessment of the effect of ß-CD and Cor elicitors on tropane alkaloid production.