The discovery of natural sources of biologically active compounds is crucial to medicine, organic farming, plant science, etc. Amaryllidaceae alkaloids are unique compounds of plant origin with a wide variety of biological and pharmacological properties. In the present study, six different chemotypes of Galanthus populations of Bulgarian origin were used for the isolation of alkaloid extracts. The alkaloid extracts were analyzed by GC--MS, and their capability to inhibit acetylcholinesterase, Lolium perenne seed germination and root elongation was assessed. In total, 73 alkaloids of 8 main structural types were detected. Tazettine and lycorine types were predominant in G. nivalis samples, whereas tyramine, lycorine, homolycorine and galanthamine types were most abundant among G. elwesii samples. Sample GE2110, containing 74% galanthamine type alkaloids, achieved the strongest inhibition on acetylcholinesterase (IC50 = 1.32 ± 0.09 μg/mL), but also the weakest inhibition on seed germination (8 ± 5%}) and root elongation (43 ± 17%). Sample GN028A, containing 51% tazettine type alkaloids, was established as the best overall extract, with a strong inhibition on acetylcholinesterase (IC50 = 21.86 ± 1.59 μg/mL), L. perenne seed germination (75 ± 16%) and root elongation (99 ± 1%). Plant species rich in these alkaloids could be the base of a novel biocidal agent against pests and weeds.

Thymus longedentatus (Degen & Urum.) Ronniger is a Balkan endemic species valued for its essential oils and phenolic compounds, yet little is known about its phytochemistry under cultivation. This study compared the metabolite profiles of wild populations from the Eastern Rhodopes (ER) and Thracian Lowland (TL) with a cultivated population near Sofia (CA). Hydrodistillation yielded 0.2% essential oil (EO) in wild plants and 0.3% in cultivated plants. GC–MS analysis revealed citral isomers (neral and geranial) as dominant constituents, exceeding 60% in cultivated samples. Methanolic extracts and acetone exudates contained rosmarinic acid and triterpene acids consistently across all populations. Quantitative differences were observed in stress-related metabolites: arbutin and hydroquinone were enriched in wild plants, while chlorogenic and geranic acids were higher in cultivated plants. These findings demonstrate that cultivation preserves the main phytochemical profile of T. longedentatus while modulating the abundance of specific compounds, offering potential for sustainable utilization and conservation.

Hippeastrum papilio (Ravenna) Van Scheepen plant (H. papilio), endemic to South America, is an ornamental plant, a potential new source for industrial production of galanthamine (GAL). GAL is a natural compound, used for the cognitive treatment of Alzheimer's disease. In order to enhance the GAL and haemanthamine (HAEM) accumulation in H. papilio, elicitation with salicylic acid (SA) was tested in one-year-old hydroponic cultures. Three different concentrations of SA were applied (10, 50, and 100 μM/L), at various time points (0, 6, 12, 24, 48, 96, and 148 h). Gas chromatography-mass spectrometry analyses were performed to determine the alkaloid levels in leaves. The quantity of GAL and HAEM through the tested time points varied. Treatment with 100 μM/L SA for 148 h enhanced GAL biosynthesis by 19% compared to the initial level. A similar trend was observed for HAEM accumulation. The hydroponic system is suitable for H. papilio cultivation.

Narcissus species have been cultivated for centuries around the world and are mainly used as cut flowers. Although the bulbs of these species have been widely examined as sources of alkaloids and biological activity, the leaves have been understudied. In the present study alkaloid fractions of leaves from Narcissus pseudonarcissus cv. Carlton and N. poeticus L. were evaluated for inhibitory activity against seed germination of Lolium perenne L. and Trifolium pratense L. Separately, the metabolic profiles from seedlings of the target species were analyzed after treatment with a lycorine solution. The composition of methanolic extracts from seedlings and alkaloid fractions of Narcissus leaves were determined using GC/MS. The N. pseudonarcissus alkaloid fraction was more active than that of N. poeticus. Complete inhibitory activity of the alkaloid fraction was established at a concentration of 1 or 2 mg/mL, depending on the target species. Lycoramine and galanthine were identified as the main alkaloids of N. pseudonarcissus. 8-O-Demethylmaritidine, maritidine and homolycorine were found to be the predominant alkaloids of N. poeticus. Increased accumulation of some amino acids, saccharides and polyols, indicating protein synthesis inhibition, was the most common response of target species seedlings treated with 0.17 µM lycorine. The results showed the promising potential of alkaloid fractions from the leaves of Narcissus species as seed germination inhibitors. The study contributes to full utilization of the resources of these species and presents, to our knowledge, for the first time data on changes in the metabolic profiles of L. perenne and T. pratense seedlings after treatment with lycorine.