Molecular Human Targets of Bioactive Alkaloid-Type Compounds from Tabernaemontana cymose Jacq

Phytochemical Screening, Antibacterial Activity, and Toxicity of Calathea lutea Leaf Extracts

In Colombia, there is a long tradition of using bijao (Calathea lutea) leaves to package or wrap various foods. However, scientific studies on C. lutea are limited, and research to evaluate its toxicity and/or antibacterial activity has not yet been conducted. The objective of this research, therefore, was to evaluate the content of phytochemical compounds, levels of toxicity, and antibacterial activity of the extracts, fractions, and essential oil derived from C. lutea leaves. The plant material was subjected to extraction by maceration, Soxhlet extraction, and steam distillation, and fractions of hexane, dichloromethane, ethyl acetate, and a residual ethanol-water fraction were obtained. Preliminary phytochemical screening was performed using standard procedures with staining reagents. Estimation of the toxicity was carried out using the Caenorhabditis elegans biological model. Antibacterial activity was determined by broth microdilution against Staphylococcus aureus and Escherichia coli. The results showed that the characteristic metabolites were flavonoids, triterpenes, and tannins. At the concentrations tested, the extracts, fractions, and essential oil showed minimal toxicity levels. In terms of antibacterial activity, E. coli showed no susceptibility; meanwhile, the dichloromethane fraction had high antibacterial activity against S. aureus, with a growth inhibition rate of 81.2%. The results suggested that the of dichloromethane fraction of C. lutea has antibacterial activity against S. aureus, suggesting its potential as a possible candidate as a natural antibacterial agent in the food industry. This alternative could offer a safer and more sustainable solution compared to the conventional synthetic preservatives.

An update review on monoterpene indole alkaloids and biological activities of Tabernaemontana species occurring in Brazil

ETHNOPHARMACOLOGICAL RELEVANCE

The Tabernaemontana genus belongs to the Apocynaceae family of which 30 species are found in Brazil. Some Tabernaemontana species are used by Brazilian indigenous people and other communities, or are listed in the Yanomami Pharmacopeia. Ethnopharmacological data include use(s) for muscle problems, depressed sternum, back pain, abscess, indigestion, eye irritation, earache, itching, vaginal discharge, as an aid for older people who are slow and forgetful, mosquito and snake bites, infection by the human botfly larvae, calmative, and fever. Obviously, many of these uses are attributed to the alkaloids found in Tabernaemontana species.

AIM OF THE REVIEW

The aim is to gather information on Tabernaemontana species occurring in Brazil, as sources of monoterpene indole alkaloids (MIAs). In addition, we aim to collect reported experimental demonstrations of their biological activity, which may provide the foundation for further studies, including phytochemistry, the development of medicinal agents, and validation of phytopreparations.

MATERIAL AND METHODS

The Brazilian Flora 2020 database was used as source for Tabernamontana species occurring in Brazil. The literature review on these species was collected from Web of Science, Scopus, PubMed, and Scifinder. The keywords included names and synonyms of Tabernaemontana species found in Brazil, which were validated by the Word Flora Online Plant List.

RESULTS

A literature survey covering the time frame from 1960 until June 2023 resulted in 121 MIAs, including 48 not yet reported in the last review published in 2016. Some alkaloid extracts, fractions, and isolated alkaloids present evidenced biological activity, such as anticancer, anti-inflammatory, antinociceptive, antimicrobial, antiparasitic, antiviral, and against snake venoms, among others. Notably, ethnopharmacological based information has been the basis of some reports on Tabernaemontana species.

CONCLUSIONS

Our literature survey shows that Tabernaemontana species present bioactive MIAs, such as voacamine and affinisine, demonstrating significant cytotoxicity activity against several tumoral cell lines. Those compounds can be considered promising candidates in the search for new anticancer drugs. However, the Amazonian plant biome is increasingly damaged, which may lead to the extinction of biological diversity. This threat may also affect Tabernaemontana species, which have scarcely been investigated regarding the potential of their phytochemicals for the development of new drugs.

Investigation on the Mechanisms of Zanthoxylum bungeanum for Treating Diabetes Mellitus Based on Network Pharmacology, Molecular Docking, and Experiment Verification

OBJECTIVE

The aim of the study was to explore the potential mechanism of Zanthoxylum bungeanum in the treatment of diabetes mellitus (DM) using network pharmacology.

METHODS

The DrugBank database and TCMSP platform were used to search for the main chemical components and their targets of Zanthoxylum bungeanum, and the genes related to diabetes mellitus were obtained from the genecards database. Import the data into the Venny 2.1.0 platform for intersection analysis to obtain the Zanthoxylum bungeanum-DM-gene dataset. The protein-protein interaction (PPI) analysis of Zanthoxylum bungeanum-DM gene was performed using the String data platform, and the visualization and network topology analysis were performed using Cytoscape 3.8.2. The KEGG pathway enrichment and biological process of GO enrichment analysis were carried out using the David platform. The active ingredients and key targets of Zanthoxylum bungeanum were molecularly docked to verify their biological activities by using Discovery Studio 2019 software. Zanthoxylum bungeanum was extracted and isolated by ethanol and dichloromethane. HepG2 cells were cultured, and cell viability assay was utilized to choose the suitable concentration of Zanthoxylum bungeanum extract (ZBE). The western blot assay was used for measuring the expression of AKT1, IL6, HSP90AA1, FOS, and JUN proteins in HepG2 cells.

RESULTS

A total of 5 main compounds, 339 targets, and 16656 disease genes were obtained and retrieved, respectively. A total of 187 common genes were screened, and 20 core genes were finally obtained after further screening. The antidiabetic active ingredients of Zanthoxylum bungeanum are kokusaginin, skimmianin, diosmetin, beta-sitosterol, and quercetin, respectively. The main targets for its antidiabetic effect are AKT1, IL6, HSP90AA1, FOS, and JUN, respectively. GO enrichment analysis revealed that the biological process of Zanthoxylum bungeanum and DM is related to a positive regulation of gene expression, positive regulation of transcription, positive regulation of transcription from RNA polymerase II promoter, response to drug, positive regulation of apoptotic process, and positive regulation of cell proliferation, etc. KEGG enrichment analysis revealed that common biological pathways mainly including the phospholipase D signaling pathway, MAPK signaling pathway, beta-alanine metabolism, estrogen signaling pathway, PPAR signaling pathway, and TNF signaling pathway. Molecular docking results showed that AKT1 with beta-sitosterol and quercetin, IL-6 with diosmetin and skimmianin, HSP90AA1 with diosmetin and quercetin, FOS with beta-sitosterol and quercetin, and JUN with beta-sitosterol and diosmetin have relatively strong binding activity, respectively. Experiment verification results showed that DM could be significantly improved by downregulating the expression of AKT1, IL6, HSP90AA1, FOS, and JUN proteins after being treated at concentrations of 20 μmol/L and 40 μmol/L of ZBE.

CONCLUSION

The active components of Zanthoxylum bungeanum mainly including kokusaginin, skimmianin, diosmetin, beta-sitosterol, and quercetin. The therapeutic effect of Zanthoxylum bungeanum on DM may be achieved by downregulating core target genes including AKT1, IL6, HSP90AA1, FOS, and JUN, respectively. Zanthoxylum bungeanum is an effective drug in treatment of DM related to the above targets.

Apoptosis promoting activity of selected plant steroid in MRMT-1 breast cancer cell line by modulating mitochondrial permeation pathway

Escape from apoptosis is one of the main demeanor characteristics of cancer cells. Mitochondria are key players in initiating and regulating the intrinsic apoptosis pathway. Hexokinase2 (HK2) is ubiquitously expressed in several cancer cells and is essential for cell survival and death. The binding of HK2 to mitochondria promotes cell proliferation, while AKT-1 mediated pathway is crucial in this process. Peimine, a steroidal alkaloid derived from plant steroids, is screened for docking properties, ADMET properties, and drug-likeness. Apoptosis targets are predicted by network pharmacology using 47 genes associated with apoptosis. According to in silico study, peimine has the potential for dual Targeting on HK2 and AKT1. For further confirmation, peimine was subjected to Cell culture studies using MRMT-1 rat breast cancer cells. The elevated levels of cytochrome c and Caspase 9 activity indicate that the intrinsic apoptosis pathway causes cell death. The decreased glucose uptake by the MRMT-1 cells indicates that pimine inhibits glucose transport by inhibiting the membrane HK2.

In Vitro and In Silico Antistaphylococcal Activity of Indole Alkaloids Isolated from Tabernaemontana cymosa Jacq (Apocynaceae)

The species of the genus Tabernaemontana have a long tradition of use in different pathologies of infectious origins; the antibacterial, antifungal, and antiviral effects related to the control of the pathologies where the species of this genus are used, have been attributed to the indole monoterpene alkaloids, mainly those of the iboga type. There are more than 1000 alkaloids isolated from different species of Tabernaemontana and other genera of the Apocynaceae family, several of which lack studies related to antibacterial activity. In the present study, four monoterpene indole alkaloids were isolated from the seeds of the species Tabernaemontana cymosa Jacq, namely voacangine (1), voacangine-7-hydroxyindolenine (2), 3-oxovoacangine (3), and rupicoline (4), which were tested in an in vitro antibacterial activity study against the bacteria S. aureus, sensitive and resistant to methicillin, and classified by the World Health Organization as critical for the investigation of new antibiotics. Of the four alkaloids tested, only voacangine was active against S. aureus, with an MIC of 50 µg/mL. In addition, an in silico study was carried out between the four isolated alkaloids and some proteins of this bacterium, finding that voacangine also showed binding to proteins involved in cell wall synthesis, mainly PBP2 and PBP2a.