With this paper we continue a new annual series, the main purpose of which is to make significant floristic findings from Russia and neighboring countries more vi sible in Russia and abroad. In total, this paper presents new records for 24 vascular plant species from 4 Eurasian countries, obtained during field explorations, as well as during taxonomic revisions of herbarium materials. For the first time, new locali ty of Ageratum conyzoides, Salvia hispanica, Thymus rasitatus, Tulipa mongolica is recorded for Russia, Sparganium glomeratum for North Korea, Alyssum armenum for Georgia, Thymus pseudopannonicus for Kazakhstan, Cymbalaria muralis for the Asian part of Russia, Anthemis ruthenica for Siberia, Capsella orientalis, Echinops sphaerocephalus, Hera cleum sosnowskyi, Thymus elegans for Eastern Siberia, Persicaria orientalis for Western Si beria, Galatella crinitoides for the Black Soil Region, Centaurea orientalis for Zavolzhye, Silene dichotoma for the Altai Republic, Onobrychis arenaria, Symphyotrichum squamatum, Verbesina encelioides for the Republic of Dagestan, Geranium dahuricum for the Re public of Sakha (Yakutia), Koeleria spryginii for the Republic of Tatarstan, Phacelia tanacetifolia for Sakhalin, Adonis wolgensis for Novosibirsk Region. For each species, the general distribution, habitat, and taxonomy, indicating differences from related species and location are presented.

For the first time, new locality of Viola suavis is recorded for the Asian part of Rus sia, Chloris virgata, × Elyhordeum arcuatum and Persicaria orientalis for Siberia, Thalic trum amurense for Japan, Eritrichium pseudolatifolium and E. pseudostrictum for Kirghizia, Aquilegia jucunda, A. vulgaris and Viola hirta for Baikal Siberia, Astragalus pallescens and A. physodes for the North Caucasus, Astragalus guttatus for the Central Caucasus, Astragalus somcheticus, Lotus frondosus and Vicia bithynica for Dagestan, Medicago × varia and Lappula tuvinica for the Irkutsk region. For each species, the general distribu tion, habitat, and taxonomy, indicating differences from related species and loca tion are presented.

Eranthis longistipitata Regel is an endemic plant of Central Asia. The flavonoid profile of E. longistipitata leaves was studied by mass spectrometry for the first time (natural populations of Kyrgyzstan and Uzbekistan, in 70% aqueous–ethanol extracts by liquid chromatography coupled with high-resolution mass spectrometry). Mass spectrometry revealed 18 flavonoid compounds. Flavonols featured the highest diversity, and 10 such substances were identified: 2 free aglycones (quercetin and kaempferol), 6 quercetin glycosides (peltatoside, hyperoside, reynoutrin, quercetin 3-sambubioside, rutin, and isoquercitrin), and 2 kaempferol glycosides (juglalin and trifolin). Two flavans (cianidanol and auriculoside), two hydroxyflavanones (6-methoxytaxifolin and aromadendrin), and one C-glycoside flavone—carlinoside—were identified. Dihydroxychalcones aspalathin, phloridzin, and phloretin were found too. Levels of rutin, quercetin, kaempferol, and hyperoside were confirmed by means of standards and high-performance liquid chromatography. Rutin concentration was the highest among all other identified flavonoid compounds: in the leaf samples from Kyrgyzstan, it ranged from 2.46 to 3.20 mg/g, and in those from Uzbekistan, from 1.50 to 3.01 mg/g. The diversity of flavonoid compounds in E. longistipitata leaves is probably due to external ecological and geographic factors and adaptive mechanisms.

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Despite the fact that melanoma is a tumor of visual localization, mortality from skin melanoma remains one of the leading causes of mortality worldwide. Early metastasis of melanoma, even during the initial stages of the tumor process, indicates a high malignant potential of the tumor. Moreover, metastatic melanoma is resistant to current chemotherapy regimens, which is a significant problem today. Progression, resistance to drug therapy of skin melanoma is associated with a population of tumor stem cells, which are characterized by dysregulation of signaling pathways and aberrant phenotypes. The formation of tumor stem cells contributes to their microenvironment. Surface markers expressed by tumor stem cells include transporter proteins that mediate chemoresistance. The study of the microenvironment, the activity of the expressed antigenic determinants makes it possible to understand the processes of chemoresistance formation and to discover (develop) strategies for its overcoming. The article provides an analysis of the literature data on the significance of tumor stem cells in the development of drug resistance of melanoma.