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Phytochemical investigation of the two Tabernaemontana species (Apocynaceae) T. peduncularis Wall. and T. divaricata (L.) R.Br. ex Roem. & Schult. indicated closely related biosynthetic pathways leading to lipophilic and hydrophilic alkaloids. In total, 18 specialized metabolites comprising indole-derived alkaloid aglycones, three oxindole-derived alkaloid glycosides, and two iridoid glucosides could be identified in the studied species. Among the alkaloids, the two Iboga-type alkaloids 3,7-coronaridine isoindolenine, coronaridine 3,4-iminium and a javaniside derivative bearing a glucuronic acid, named javanuronic acid, could be described by spectroscopic and spectrometric methods for the first time. A docking experiment using alpha-fold was performed to generate a protein model of the enzyme 7-deoxyloganetic acid glucosyl transferase. Performed bioassays exhibited a growth reduction of neonate Spodoptera littoralis larvae and reduced cell viability of HepG2 cells of the extracts containing Iboga alkaloids, whilst the javaniside derivatives containing hydrophilic fraction did not show any effects. These findings indicate a high flexibility in the formation of bioactive indole alkaloid aglycones by Tabernaemontana species and also evidence similar accumulation trends in both species as well as indicate that biosynthetic routes leading to oxindole alkaloids like javanisides are more widespread than reported. Furthermore, the incorporation of the three novel compounds into potential biosynthetic pathways is discussed.

Monoterpenoid indole alkaloids (MIA) are one of the largest and most complex alkaloid class in nature, boasting many clinically significant drugs such as anticancer vinblastine and antiarrhythmic ajmaline. Many MIAs undergo nitrogen N -methylation, altering their reactivity and affinity to the biological targets through a straightforward reaction. Remarkably, all known MIA N -methyltransferases (NMT) originate from the neofunctionalization of ancestral γ-tocopherol C -methyltransferases (γTMTs), a phenomenon seemingly unique to the Apocynaceae family. In this study, we unveil and characterize a new γTMT-like enzyme from the plant Tabernaemontana elegans (toad tree): perivine N β-methyltransferase (TePeNMT). TePeNMT and other homologs form a distinct clade in our phylogenetic study, setting them apart from other γTMTs and γTMT-like NMTs discovered to date. Enzyme kinetic experiments and enzyme homology modeling studies reveal the significant differences in enzyme active sites between TePeNMT and CrPeNMT, a previously characterized perivine N β-methyltransferase from Catharanthus roseus (Madagascar periwinkle). Collectively, our findings suggest that parallel evolution of ancestral γTMTs may be responsible for the occurrence of perivine N -methylation in T. elegans and C. roseus.

The psychedelic alkaloid ibogaine has anti-addictive properties in both humans and animals 1 . Unlike most medications for the treatment of substance use disorders, anecdotal reports suggest that ibogaine has the potential to treat addiction to various substances, including opiates, alcohol and psychostimulants. The effects of ibogaine—like those of other psychedelic compounds—are long-lasting 2 , which has been attributed to its ability to modify addiction-related neural circuitry through the activation of neurotrophic factor signalling 3 , 4 . However, several safety concerns have hindered the clinical development of ibogaine, including its toxicity, hallucinogenic potential and tendency to induce cardiac arrhythmias. Here we apply the principles of function-oriented synthesis to identify the key structural elements of the potential therapeutic pharmacophore of ibogaine, and we use this information to engineer tabernanthalog—a water-soluble, non-hallucinogenic, non-toxic analogue of ibogaine that can be prepared in a single step. In rodents, tabernanthalog was found to promote structural neural plasticity, reduce alcohol- and heroin-seeking behaviour, and produce antidepressant-like effects. This work demonstrates that, through careful chemical design, it is possible to modify a psychedelic compound to produce a safer, non-hallucinogenic variant that has therapeutic potential. Psychedelic alkaloids served as lead structures for the development of tabernanthalog, a non-hallucinogenic and non-toxic analogue that reduces alcohol- and heroin-seeking behaviour and produces antidepressant-like effects in rodents.

Methods described in this paper are confined to in vitro dedifferentiated plant cell suspension cultures, which are convenient for the large-scale production of fine chemicals in bioreactors and for the study of cellular and molecular processes, as they offer the advantages of a simplified model system for the study of plants when compared with plants themselves or differentiated plant tissue cultures. The commonly used methods of initiation of a callus from a plant and subsequent steps from callus to cell suspension culture are presented in the protocol. This is followed by three different techniques for subculturing (by weighing cells, pipetting and pouring cell suspension) and four methods for growth measurement (fresh- and dry-weight cells, dissimilation curve and cell volume after sedimentation). The advantages and disadvantages of the methods are discussed. Finally, we provide a two-step (controlled rate) freezing technique also known as the slow (equilibrium) freezing method for long-term storage, which has been applied successfully to a wide range of plant cell suspension cultures.

The ability of plants to modify biomass allocation and leaf phenotypes to best utilize available resources has been heavily studied. No Tabernaemontana species have been included in this research agenda. Therefore, Tabernaemontana pandacaqui Poir. and Tabernaemontana rotensis (Kaneh.) B.C. Stone plants were subjected to 24% or 100% sunlight and various traits were determined to compare the relative level of plasticity. Midday net carbon dioxide assimilation was greater for T. rotensis in sun-grown plants, but greater for T. pandacaqui in shade-grown plants. Saturating light intensity and midday Fv/Fm were greater for T. rotensis in sun-grown plants, but did not differ between the species for shade-grown plants. Light compensation intensity was greater for T. rotensis than T. pandacaqui in both light treatments. Apparent quantum yield was greater for T. pandacaqui shade-grown plants but was similar for the two species in sun-grown plants. Greater relative root growth in full sun compared with shade was exhibited by T. rotensis but not by T. pandacaqui. These findings indicated that T. pandacaqui develops functional traits that improve performance in shade-grown plants, and T. rotensis develops facultative traits that enable performance in sun-grown plants. These insights into how T. pandacaqui and T. rotensis respond to sun and shade conditions add to the knowledge needed to inform the selection of niche conditions when using them in managed mixed forest plantings such as conservation and restoration sites.

Gentamicin (Aminoglycoside antibiotic) is notorious for causing kidney problems in both humans and animals. Tabernaemontana divaricata, a plant containing flavonoids, tannins, terpenoids and other compounds known to benefit kidneys health, is under investigation for its potential to mitigate gentamicin-induced kidney damage in Wistar rats. Adult Rats (Strain -Wistar and Sex-Female) has been divided into 4 separate groups to assess the nephroprotective and nephrocurative effects of T.divaricata in gentamicin- induced nephrotoxicity. The experimental setup was as follows: Group I received water for 28 days (control); Group II received gentamicin for 8 days (Nephrotoxic control); Group III received ethanolic extract of T. divaricata for 8 days (Nephroprotective) and Group IV received gentamicin for 8 days followed by ethanaolic extract of T. divaricata from day 9 to 28 (Nephrocurative). This improvement was marked by significant reductions in serum uric acid concentrations along with a decrease in urinary total protein levels, despite an increase in serum total protein levels. Notably, T.divaricata treated nephrocurative animals exhibited superior recovery compared to those receiving nephroprotective treatment alone. In the foreseeable future, the bioactive compounds present in T.divaricata could emerge as promising therapeutic agents for renal disorders. This suggests that T.divaricata might shield against kidney dysfunctions triggered by oxidative stress. However, further exploration through clinical trials and detailed research involving metabolomics and new biomarkers is recommended to better understand the potential health benefits of T.divaricata compounds for renal health.

Silver nanoparticles (Ag NPs) were synthesised by the reduction of Ag + to Ag 0 in the presence of enol form of flavonoids present in plant extract of Tabernaemontana divaricate ( T. divaricate ). Prepared Ag NPs were characterised using UV–Vis, XRD, HR-TEM with EDX and XPS techniques. XPS spectra exhibited peaks at 366 eV and 373 eV, which specified spin orbits for Ag 3d 3/2 , and Ag 3d 5/2 that confirmed the formation of Ag NPs. Ag NPs were spherical in shape with an average size of 30 nm as revealed by HR-TEM and FE-SEM techniques. EDX studies verified the high purity of Ag NPs with silver 46.96%, carbon 16.35%, oxygen 16.22%, nitrogen 20.25% and sulphur 0.21%. LC–MS analysis of plant extract confirmed the qualitative presence of alkaloids, tannins, flavonoids, phenols, and carbohydrates. Prepared Ag NPs showed good photocatalytic activity towards degradation of 4-Amniopyridine with 61% degradation efficiency at optimum conditions in 2 h of reaction time under visible light. The ten intermediates were found within the mass number of 0–450. Ag NPs synthesised using bio-extract have also shown good inactivation against Escherichia coli ( E. coli ) and Bacillus subtilis ( B. subtilis ) bacteria due to the availability of free radicals. Graphical abstract

Several species belonging to the genus Tabernaemontana have been well researched and utilized for their wide-ranging biological activities. A few of the most prominent species include Tabernaemontana divaricata, Tabernaemontana catharinensis, Tabernaemontana crassa, and Tabernaemontana elegans. These species and many others within the genus often display pharmacological importance, which is habitually related to their chemical constituents. The secondary metabolites within the genus have demonstrated huge medicinal potential for the treatment of infections, pain, injuries, and various diseases. Regardless of the indispensable reports and properties displayed by Tabernaemontana spp., there remains a wide variety of plants that are yet to be considered or examined. Thus, an additional inclusive study on species within this genus is essential. The current review aimed to extensively analyze, collate, and describe an updated report of the current literature related to the major alkaloidal components and biological activities of species within the genus Tabernaemontana.

Eleven monoterpenoid indole alkaloids, including three new ones, tabercrassines A–C (1–3), were isolated from the seeds of Tabernaemontana crassa. Tabercrassine A (1) is an ibogan–ibogan-type bisindole alkaloid which is formed by the polymerization of two classic ibogan-type monomers through a C3 unit aliphatic chain. Their structures were established by extensive analysis of HRESIMS, NMR, and ECD spectra. Cellular assays showed that alkaloids 1–3 all reduce Aβ42 production and inhibit phospho-tau (Thr217), a new biomarker of Alzheimer’s disease [AD] associated with BACE1-, NCSTN-, GSK3β-, and CDK5-mediated pathways, suggesting these alkaloids’ potential against AD.

Copper oxide nanoparticles (CuO NPs) are among the most commonly employed nanoparticle materials owing to their antibacterial qualities, although their primary mechanism of action (MOA) is still not completely understood. CuO NPs are synthesized in this study using leaf extract of Tabernaemontana divaricate (TDCO3), and they are then analyzed using XRD, FT-IR, SEM, and EDX analysis. The zone of inhibition of TDCO3 NPs against both gram-positive (G + ) B.  subtilis and gram-negative (G − ) K. pneumoniae bacteria was 34 mm and 33 mm, respectively. Furthermore, Cu 2+ /Cu + ions promote reactive oxygen species and electrostatically bind with the negatively charged teichoic acid in the bacterial cell wall. The anti-inflammatory and anti-diabetics analysis was conducted using standard BSA denaturation and α-amylase inhibition technique with cell inhibition values of 85.66 and 81.18% for TDCO3 NPs. Additionally, the TDCO3 NPs delivered prominent anticancer activity with the lowest IC 50 value 18.2 μg/mL in the MTT assay technique against HeLa cancer cells.