Antimicrobial ent-abietane-type diterpenoids from the roots of Euphorbia wallichii

Ent-atisane diterpenoids from Euphorbia wallichii and their anti-influenza A virus activity

The study entailed the investigation of the roots of Euphorbia wallichii, which resulted in the isolation of 29 ent-atisane diterpenoids (1-29), 14 of which were previously unknown. These previously undescribed ones were named euphorwanoids A-N (3-5, 7, 9, and 10-18). Various techniques, including comprehensive spectroscopic methods and calculated electronic circular dichroism, were employed to determine their molecular structures. Additionally, the absolute configurations of ten ent-atisane diterpenoids (1, 2, 5, 6, 8, 9, 11, 12, 14 and 16) were established through X-ray crystallographic analyses. All isolated compounds' potential to inhibit the influenza A virus in vitro were evaluated. Compounds 18, 20, and 24 exhibited notable antiviral activity against the A/Puerto Rico/8/1934 strain. Their effective concentrations for reducing viral activity (EC50 values) were found to be 8.56, 1.22, and 4.97 μM, respectively. An intriguing aspect of this research is that it marks the first instance of ent-atisane diterpenes displaying anti-H1N1 activity. Empirical NMR rules were established with Δδ to distinguish the R/S configurations of C-13 and C-16 in ent-atisanes.

Diterpenoids from Euphorbia lactea and their anti-HIV-1 activity

Nine undescribed diterpenoids, euphlactenoids A-I (1-9), including four ingol-type diterpenoids (1-4) with a 5/3/11/3-tetracyclic framework and five ent-pimarane-type diterpenoids (5-9), together with thirteen known diterpenoids (10-22), were identified from the leaves and stems of Euphorbia lactea Haw. The structures and absolute configurations of compounds 1-9 were unequivocally elucidated on the basis of spectroscopic analysis, ECD calculations and single crystal X-ray diffraction. Compounds 3 and 16 showed anti-HIV-1 effects with IC₅₀ values of 1.17 μM (SI = 16.54) and 13.10 μM (SI = 1.93), respectively.

Ent-kauranes and ent-atisanes from Euphorbia wallichii and their anti-inflammatory activity

Phytochemical investigation on the whole plant of Euphorbia wallichii led to the identification of twelve diterpenoids, including nine undescribed ones, in which wallkauranes A-E (1-5) were classified as ent-kaurane diterpenoids and wallatisanes A-D (6-9) were assigned as ent-atisane diterpenoids. The biological evaluation of these isolates against NO production was conducted in the LPS-induced RAW264.7 macrophage cells model, resulting in the identification of a series of potent NO inhibitors, with the most active wallkaurane A showing an IC₅₀ value of 4.21 μM. The mechanistic study disclosed that wallkaurane A could inhibit pro-inflammatory cytokines generation such as TNF-α, IL-1β, and IL-6, and decrease the expression of iNOS and COX-2. Wallkaurane A could regulate the NF-κB signaling pathways and the JAK2/STAT3 signaling pathway to suppress the inflammatory reaction in LPS-induced RAW264.7 cells. Meanwhile, wallkaurane A could also inhibit the JAK2/STAT3 signaling pathway, thereby suppressing apoptosis in LPS-induced RAW264.7 cells.

Diterpenoids with anti-inflammatory activity from Euphorbia wallichii

The Euphorbia plants are the focus of natural product drug discovery because of their fascinating structural diversity and broad biological activities. Here we reported the discovery of eight undescribed diterpenoids, including two ent-trachylobanes, five ent-atisanes, and one ent-abietane, together with 15 known ones from the whole plant of Euphorbia wallichii. Their chemical structures were elucidated by detailed spectrometry data analysis and X-ray crystallography. Among them, wallichane G represents a rare ent-atisane type pentacyclic diterpenoid featuring a tetrahydrofuran moiety. Furthermore, bioassays indicated that jolkinolide B exhibited potent inhibitory activities on the production of NO, with an IC₅₀ value of 3.84 ± 0.25 μM. Meanwhile, the mechanistic study revealed that jolkinolide B could obviously downregulate the expression of iNOS, COX-2, NF-κB, and phosphorylated IκBα in a dose-dependent manner and strongly upregulate the expression of Nrf2 and HO-1 protein, thereby suppressing the inflammatory process in macrophage cells induced by LPS.

Phytochemical and pharmacological review of diterpenoids from the genus Euphorbia Linn (2012-2021)

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia is one of the major genera in angiosperms, which is widely distributed all over the world, including Asia, Africa and Central and South America. The roots or tubers of Euphorbia are famous for medicinal purposes, especially in China. Many of them, such as Euphorbia pekinensis Rupr, Euphorbia fischeriana Steud and Euphorbia Kansui S.L.Liou ex S.B.Ho. . are used as Chinese herbal medicines.

AIM OF THE STUDY

This paper reviews the diterpenoids isolated from the genus Euphorbia species and the pharmacological activities of these compounds to evaluate its traditional use and potential future development.

MATERIALS AND METHODS

Information on the studies of the genus Euphorbia Linn was collected from scientific journals, books and reports via library and electronic data search (Scifinder, Web of Science, PubMed, Elsevier, Scopus, Google Scholar, Springer, Science Direct, Wiley, ACS, CNKI and Kew Plants of the Word Online). Meanwhile, it was also obtained from published works of material medica, folk records, ethnophmacological literatures, Ph.D. and Masters dissertations.

RESULTS

Known as the main constituents of the genus Euphorbia Linn, Diterpenoids possess many pharmacological properties such as anti-inflammation, antiviral activities and cytotoxicity. To date, various types of diterpenoids were identified from this genus, including isopimarane, rosane, abietane, ent-kaurane, ent-atisane. cembrane, casbane, lathyrane, myrsinane, jatropholane, tigliane, ingenane, jatrophane, paraliane, pepluane, and euphoractin.

CONCLUSIONS

This review describes 14 types of diterpenoid isolated from 45 Euphorbia species from 2012 to 2021, a total of 615 compounds. Among them, mainly include jatrophane (171), lathyrane (92), myrsinane (62), abietane (70), ent-atisane (36), ent-kaurane (7), tigliane (26) and ingenane (19). The possible biological pathways of these compounds were presumed. At the same time, more than 10 biological activities of these compounds were summarized, such as anti-inflammation, antiviral activities and cytotoxicity.

Euphorbia diterpenoids: isolation, structure, bioactivity, biosynthesis, and synthesis (2013-2021)

Covering: 2013 to 2021As the characteristic metabolites of Euphorbia plants, Euphorbia diterpenoids have always been a hot topic in related science communities due to their intriguing structures and broad bioactivities. In this review, we intent to provide an in-depth and extensive coverage of Euphorbia diterpenoids reported from 2013 to the end of 2021, including 997 new Euphorbia diterpenoids and 78 known ones with latest progress. Multiple aspects will be summarized, including their occurrences, chemical structures, bioactivities, and syntheses, in which the structure-activity relationship and biosynthesis of this class will be discussed for the first time.

Tigliane and rhamnofolane glycosides from Euphorbia wallichii prevent oxidative stress-induced neuronal death in PC-12 cells

Tigliane and rhamnofolane diterpenoids bearing glycosyl substituents are rarely found in nature. In the current study, seven new tigliane glycosides, euphorwallsides A - G (1-7), and five new rhamnofolane glycosides, euphorwallsides H - L (8-12), were isolated from the whole plants of Euphorbia wallichii. Their structures were elucidated by a combination of spectroscopic, computational, and chemical means. The aglycones of 1-5 represent a rare class of 13-deoxygenated tiglianes, while those of 8-12 represent the first examples of 4-deoxygenated rhamnofolanes. 2, 3, 5, 7, 8, and 12 showed significant neuroprotective effects on sodium nitroprusside (SNP)-induced neuronal death in pheochromocytoma cell line PC-12 at 10 μM, being more active than the clinical drug, edaravone. Mechanistic study revealed that the most active compound, 3, could inhibit reactive oxygen species (ROS) accumulation and restore the mitochondrial membrane potential via modulating the Nrf2 signaling pathway in PC-12 cells.

Green Synthesis of Silver Nanoparticles Using Euphorbia wallichii Leaf Extract: Its Antibacterial Action against Citrus Canker Causal Agent and Antioxidant Potential

Biologically synthesized silver nanoparticles are emerging as attractive alternatives to chemical pesticides due to the ease of their synthesis, safety and antimicrobial activities in lower possible concentrations. In the present study, we have synthesized silver nanoparticles (AgNPs) using the aqueous extract of the medicinal plant Euphorbia wallichii and tested them against the plant pathogenic bacterium Xanthomonas axonopodis, the causative agent of citrus canker, via an in vitro experiment. The synthesized silver nanoparticles were characterized by techniques such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction analysis and transmission electron microscopy. Moreover, the plant species were investigated for phenolics, flavonoids and antioxidant activity. The antioxidant potential of the extract was determined against a DPPH radical. The extract was also evaluated for phenolic compounds using the HPLC technique. The results confirmed the synthesis of centered cubic, spherical-shaped and crystalline nanoparticles by employing standard characterization techniques. A qualitative and quantitative phytochemical analysis revealed the presence of phenolics (41.52 mg GAE/g), flavonoids (14.2 mg QE/g) and other metabolites of medicinal importance. Different concentrations (1000 µg/mL to 15.62 µg/mL—2 fold dilutions) of AgNPs and plant extract (PE) alone, and both in combination (AgNPs-PE), exhibited a differential inhibition of X. axanopodis in a high throughput antibacterial assay. Overall, AgNPs-PE was superior in terms of displaying significant antibacterial activity, followed by AgNPs alone. An appreciable antioxidant potential was recorded as well. The observed antibacterial and antioxidant potential may be attributed to eight phenolic compounds identified in the extract. The Euphorbia wallichii leaf-extract-induced synthesized AgNPs exhibited strong antibacterial activity against X. axanopodis, which could be exploited as effective alternative preparations against citrus canker in planta in a controlled environment. In addition, as a good source of phenolic compounds, the plant could be further exploited for potent antioxidants.

In vitro antibacterial and cytotoxic effects of Euphorbia grandicornis Blanc chemical constituents

BACKGROUND

Euphorbia grandicornis is widely utilized in traditional medicine for the treatment of microbial infections including sexually transmitted diseases such as syphilis, gonorrhoea and for healing of wounds.

OBJECTIVE

The aim of this work was to isolate and evaluate the antibacterial and anticancer activities of Euphorbia grandicornis chemical constituents.

METHODS

Chemical constituents were isolated and identified using various spectroscopic techniques such as IR, MS, and NMR. The single point growth inhibitory potential of the compounds was determined using a 96-well plate based assay.

RESULTS

The CH₂Cl₂ crude extracts exhibited potent antibacterial activity against Escherichia coli ATCC 8739 and Staphylococcus aureus ATCC 6538 with percentage growth of 94.90 ± 4.24 and 29.47 ± 4.89 respectively. Hence, the CH₂Cl₂ crude extract was further subjected to column chromatography which resulted in the isolation of methyl 2,5-dihydroxybenzoate (1), n-octyl benzoate (2), friedelanol (3), and germanicol (4) and identification of compounds 12-24 for the first time in the species based on the LC-MS/MS spectroscopic data. The purified compounds (1-4), and previously reported compounds (5-11) were evaluated for antibacterial activities against S. aureus and E. coli, as well as the cytotoxicity effects against HeLa cells. Of the purified compounds, methyl 2,5-dihydroxybenzoate (1), was the most active against E.coli and S. aureus with a percentage growth of 19.12 ± 0.65 and 23.32 ± 0.23 respectively. β-amyrin (6), and β-sitosterol (8), were active against S. aureus with percentage growth of 27.17 ± 0.07, and 47.79 ± 2.99 respectively.

CONCLUSION

The results obtained from this study indicate that E. grandicornis, is a rich source of chemical constituents that may provide new lead compounds for the development of antibacterial agents.

Antimicrobial Diterpenes: Recent Development From Natural Sources

Antimicrobial resistance has been posing an alarming threat to the treatment of infectious diseases over the years. Ineffectiveness of the currently available synthetic and semisynthetic antibiotics has led the researchers to discover new molecules with potent antimicrobial activities. To overcome the emerging antimicrobial resistance, new antimicrobial compounds from natural sources might be appropriate. Secondary metabolites from natural sources could be prospective candidates in the development of new antimicrobial agents with high efficacy and less side effects. Among the natural secondary metabolites, diterpenoids are of crucial importance because of their broad spectrum of antimicrobial activity, which has put it in the center of research interest in recent years. The present work is aimed at reviewing recent literature regarding different classes of natural diterpenes and diterpenoids with significant antibacterial, antifungal, antiviral, and antiprotozoal activities along with their reported structure–activity relationships. This review has been carried out with a focus on relevant literature published in the last 5 years following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 229 diterpenoids from various sources like plants, marine species, and fungi are summarized in this systematic review, including their chemical structures, classification, and significant antimicrobial activities together with their reported mechanism of action and structure–activity relationships. The outcomes herein would provide researchers with new insights to find new credible leads and to work on their synthetic and semisynthetic derivatives to develop new antimicrobial agents.

Euphorbia Diterpenes: An Update of Isolation, Structure, Pharmacological Activities and Structure-Activity Relationship

Euphorbia species have a rich history of ethnomedicinal use and ethnopharmacological applications in drug discovery. This is due to the presence of a wide range of diterpenes exhibiting great structural diversity and pharmacological activities. As a result, Euphorbia diterpenes have remained the focus of drug discovery investigations from natural products. The current review documents over 350 diterpenes, isolated from Euphorbia species, their structures, classification, biosynthetic pathways, and their structure-activity relationships for the period covering 2013-2020. Among the isolated diterpenes, over 20 skeletal structures were identified. Lathyrane, jatrophane, ingenane, ingenol, and ingol were identified as the major diterpenes in most Euphorbia species. Most of the isolated diterpenes were evaluated for their cytotoxicity activities, multidrug resistance abilities, and inhibitory activities in vitro, and reported good activities with significant half-inhibitory concentration (IC50) values ranging from 10-50 µM. The lathyranes, isopimaranes, and jatrophanes diterpenes were further found to show potent inhibition of P-glycoprotein, which is known to confer drug resistance abilities in cells leading to decreased cytotoxic effects. Structure-activity relationship (SAR) studies revealed the significance of a free hydroxyl group at position C-3 in enhancing the anticancer and anti-inflammatory activities and the negative effect it has in position C-2. Esterification of this functionality, in selected diterpenes, was found to enhance these activities. Thus, Euphorbia diterpenes offer a valuable source of lead compounds that could be investigated further as potential candidates for drug discovery.