Dodders (Cuscuta spp.) are prominent parasitic plants widely known and exploited in traditional medicine. They are rich in polyphenolics, which determine their strong antioxidant potential. However, comparatively few of the nearly 200 known species have been characterized for their medicinal potential. In the present study, we aimed to explore the antioxidant potential of four of the most widely distributed Cuscuta species in Bulgaria—C. campestris, C. monogyna, C. epithymum, and C. europaea. They differed significantly in polyphenolic content and accordingly differed in their antioxidant properties, although this correlation is not always straightforward, as shown in C. europaeae. Furthermore, we evaluated the host plant species’ influence on the polyphenolic content, antioxidant properties, and flavonoid profile of C. campestris, finding a significant enhancement when the parasite was grown on aromatic plants—rosemary and thyme—compared to a model host—Arabidopsis thaliana. Seven major flavonoids and phenolic acids—chlorogenic acid, kaempferol-3,7-O-diglucoside, quercetin-3-O-galactoside, kaempferol-3-O-galactoside, quercetin-3-O-glucoside, astragalin, and isorhamnetin-7-glucoside—were annotated after HPLC-MS analysis and found to be affected by the host species. In conclusion, it was found that extracts from different Cuscuta species differ in their antioxidant potential, which the host plants might further modify.

Holoparasitic plants of the genus Cuscuta are generally considered prominent agricultural pests. In addition to their negative economic effect on agriculture and their impact on natural plant societies, they have also been long known in East Asian as medicinal plants with beneficial properties. This underlines the fact that Cuscuta spp. are particularly rich in specialized metabolites, flavonoids, alkaloids, and cumarines, among others. In addition to several well-characterized species, most of the species variety within the genus remains largely unstudied. In the present study we aimed to compare the flavonoid profiles of natural populations of two of the most abundant Cuscuta species in Bulgaria—the native C. epithymum, and the naturalized C. campestris. Based on HPLC-MS/MS analysis, a total of 13 polyphenolics compounds were annotated, with hyperoside and isoquercitrin being some of the most abundant. Some notable differences were found, like the complete absence of dicaffeoylquinic acid in C. campestris, and kaempferol-3,7-O-diglucoside and kaempferol 3-O-β-(6′′-O-trans-p-coumaroyl)-glucopyranoside in C. epithymum. The population of the two species clustered separately from each other, with some variations, but with no clear pattern of dependence on the locality or host species. Based on the results it can be concluded that flavonoids may be used as chemotaxonomical markers within the genus, showing that even in different climatic conditions and different host ranges, the two studied species clearly differed from each other. Also, their rich content emphasizes the potential of these parasites as a source of bioactive compounds.

Plants are continuously subjected to the unfavorable impact of abiotic stress factors, of which soil salinity is among the most adverse. Although away from direct soil contact throughout most of their lifecycle, stem parasitic plants of the genus Cuscuta, family Convolvulaceae are also affected by salinity. The present study aimed to assess salt stress impact on germination and early establishment of three Cuscuta species, in comparison to related nonparasitic vines of the same family. It was found, that Cuscuta spp. are highly sensitive to NaCl concentration within the range of 200 mM. Germination was delayed in time and reduced by nearly 70%, accompanied by decrease in further seedling growth, ability to infect host plants and growth rate of established parasites. The nonparasitic vines showed similar sensitivity to salinity at germination level, but appeared to adapt better after the stress factor was removed. However, the negative effect of salinity did not fully prevent some of the Cuscuta species from infecting hosts, probably a beneficial characteristic at a species level, allowing the parasite to successfully thrive under the scarce host availability under saline conditions.

Nepeta nuda L. (Lamiaceae) is a medicinal plant with a wide distribution in Europa and Asia. In Bulgaria, N. nuda is also known as “naked (or hairless) catmint”, which likely refers to the naked or sparse short hairy stem and leaves. This study aims to generate DNA barcodes for precise genetic discrimination and determination of phylogenetic position of the plant among other Nepeta species. To achieve this goal, we applied the DNA barcoding technique based on conserved nuclear (internal transcribed spacer/ITS) and chloroplast (rbcL, matK, trnH) DNA regions. The generated DNA barcode sequences were submitted to the Barcode of Life Data System (BOLD) database (https://www.boldsystems.org; accession number BUL002-22). The obtained N. nuda DNA barcodes and corresponding sequences of other Nepeta species available in the BOLD and NCBI database were utilized for taxonomic classification. ITS-derived sequences for Nepeta species were the most enriched in the database, and DNA fragments matching 47 Nepeta species were selected for construction of phylogenetic tree. The results show that N. nuda is clustered in a subclade together with N. sheilae, N. deflersiana, N. isaurica, N. congesta, N. heliotropifolia, N. schiraziana and N. cataria. The information in BOLD was also retrieved for rbcL and matK, and corresponded to 15 and 10 different Nepeta species, respectively. For trnH, only NCBI sequences corresponding to 6 different Nepeta species were found. Тhe three chloroplast markers highlighted the close relation of N. nuda to N. italica, N. tuberosa, N. cataria, N. grandiflora and N. hemsleyana. In conclusion, we suggest a DNA barcode system for genetic discrimination of N. nuda, which could assist its accurate taxonomic characterization.

The data on the distribution in Bulgaria of the species from genus Lathyrus were summarized and revised. The collections from the main Bulgarian Herbariums SO, SOM and SOA were checked. New chorological data for 10 taxa were found: L. annuus, L. inconspicuus, L. pannonicus, L. sativus, L. setifolius, L. venetus, L. digitatus var. puberulus, L. latifolius var. brachypterus, L. sylvestris var. platyphyllos, L. venetus var. grandis. The taxon L. inconspicuus var. inconspicuus is reported as a new one for the Bulgarian flora.