Comparison of the profiles of non-glycosylated triterpenoids from leaves of plants of selected species of genus Dioscorea

Remarkable qualitative and quantitative differences in non-glycosylated triterpenoid profiles of twelve Dioscorea spp. leaves were demonstrated with the use of GC-MS/FID analysis. The total content of tetracyclic triterpenoids and their esters ranged from 397 μg/g of dry leaf weight in D. bulbifera to 762 μg/g d.w. in D. discolor and 777 μg/g d.w in D. alata. Three main phytosterols, i.e. campesterol (1), sitosterol (2) and stigmasterol (3) were found in extracts from all analyzed species in total amount ranging from 316 μg/g in D. bulbifera to 676 μg/g of dry leaf weight in D. hispida, with either sitosterol (2) or stigmasterol (3) as predominant in the profile. Extracts from D. hispida and D. purpurea leaves were distinguished from the others by particular high amount of campesterol (1). In the majority of the species, except for D. caucasica, other tetracyclic triterpenoids were found: cycloartanol (4), 24-methylenecycloartanol (5) and cycloeucalenol (6). Less common steroids, stigmastan-3-en-6β-ol (7) and ergosta-7,22-dien-3β-ol (8) were detected in D. japonica. The significant content (992 μg/g) of pentacyclic triterpenoids of ursane, oleanane, taraxastane and taraxerene (friedooleanane)-type carbon skeletons, i.e. α-amyrin (9), β-amyrin (10), taraxasterol (11) and taraxerol (12), respectively, was found in D. caucasica. The obtained results supplement the knowledge of biochemical diversity of Dioscorea genus

GC-MS analysis of steroids and triterpenoids occurring in leaves and tubers of Tamus edulis Lowe

Tamus edulis Lowe is an endemic perennial plant belonging to Dioscoreaceae family. The plant has long climbing stems, ovate leaves, flowers in spikes, fleshy red berries and long tuberous roots. Young shoots and tuberous roots of T. edulis were used traditionally for nourishment and as a herbal medicine. Leaves and roots analyzed in the present study were collected in the northwest of Madeira island. The GC–MS analysis allowed to detect several steroids in free forms in diethyl ether extracts; and diosgenin with its isomer, yamogenin, in hydrolyzates from methanolic extracts.The obtained results reveal that Tamus edulis has some features common with other Dioscorea species, e.g., the presence of steroidal saponins with diosgenin and yamogenin as aglycones, or the phytosterol composition with predominating sitosterol. However, some other traits, like the relatively high content of free steroids (more than 1 mg/g d.w.) and their profile rich in cholesterol derivatives, can distinguish Tamus edulis from other Dioscorea species studied previously for their steroid and triterpenoid profile.info:eu-repo/semantics/publishedVersio

Modeling of Dolichol Mass Spectra Isotopic Envelopes as a Tool to Monitor Isoprenoid Biosynthesis1

The cooperation of the mevalonate (MVA) and methylerythritol phosphate (MEP) pathways, operating in parallel in plants to generate isoprenoid precursors, has been studied extensively. Elucidation of the isoprenoid metabolic pathways is indispensable for the rational design of plant and microbial systems for the production of industrially valuable terpenoids. Here, we describe a new method, based on numerical modeling of mass spectra of metabolically labeled dolichols (Dols), designed to quantitatively follow the cooperation of MVA and MEP reprogrammed upon osmotic stress (sorbitol treatment) in Arabidopsis (Arabidopsis thaliana). The contribution of the MEP pathway increased significantly (reaching 100%) exclusively for the dominating Dols, while for long-chain Dols, the relative input of the MEP and MVA pathways remained unchanged, suggesting divergent sites of synthesis for dominating and long-chain Dols. The analysis of numerically modeled Dol mass spectra is a novel method to follow modulation of the concomitant activity of isoprenoid-generating pathways in plant cells; additionally, it suggests an exchange of isoprenoid intermediates between plastids and peroxisomes

Modulation of Steroid and Triterpenoid Metabolism in Calendula officinalis Plants and Hairy Root Cultures Exposed to Cadmium Stress

The present study investigated the changes in the content of steroids and triterpenoids in C. officinalis hairy root cultures and plants exposed to cadmium stress. The observed effects included the content and composition of analyzed groups of compounds, particularly the proportions among individual sterols (e.g., stigmasterol-to-sitosterol ratio), their ester and glycoside conjugates. The total sterol content increased in roots (by 30%) and hairy root culture (by 44%), whereas it decreased in shoots (by 15%); moreover, these effects were inversely correlated with Cd-induced growth suppression. Metabolic alterations of sterols and their forms seemed to play a greater role in the response to Cd stress in roots than in shoots. The symptoms of the competition between general metabolites (sterols) and specialized metabolites (triterpenoids) were also observed, i.e., the increase of the sterol biosynthesis parallel to the decrease of the triterpenoid content in C. officinalis plant roots and hairy root culture, and the inverse phenomenon in shoots. The similarity of the metabolic modifications observed in the present study on C. officinalis plant roots and hairy roots confirmed the possibility of application of plant in vitro cultures in initial studies for physiological research on plant response to environmental stresses

Triterpenoid profile of fruit and leaf cuticular waxes of edible honeysuckle Lonicera caerulea var. kamtschatica

Edible honeysuckle (honeyberry) Lonicera caerulea is becoming popular as a novel berry crop with several useful features such as early fruit ripening and exceptional hardiness, particularly resistance to pests and diseases as well as severe frosts in winter and droughts in summer. The triterpenoid profile of fruit and leaf cuticular waxes of edible honeysuckle (a Russian cultivar Chernichka) was analyzed by GC-MS. The major compounds identified were the tetracyclic triterpenoids campesterol, cholesterol, cycloartanol, cycloart-23-ene-3,25-diol, 24-methylenecycloartanol (only in leaves), sitosterol, stigmasta-3,5-dien-7-one, and stigmasterol; and the pentacyclic triterpenes: α-amyrin, β-amyrin, hop-22(29)-en-3-one, oleanolic acid, and ursolic acid. Several remarkable features of the analyzed triterpenoid contents were revealed, including the relatively low abundance of triterpenoids in fruit waxes (6.5% of wax extract) compared to leaf waxes (22%), and a particularly high proportion of tetracyclic triterpenoids (tetracyclic to pentacyclic compound ratios of 4:1 in fruits and almost 7:1 in leaves). These rare features distinguish the triterpenoid profile of the cuticular waxes of L. caerulea var. kamtschatica from the majority of triterpenoid profiles in plant cuticular waxes investigated to date. To our knowledge, this is the first quantitative compositional study on triterpenoid compounds in the cuticular waxes of edible honeysuckle, supplementing the knowledge of cuticular triterpenoid diversity and distribution