Dimeric Abietane Diterpenoids and Sesquiterpenoid Lactones from Teucrium viscidum

Isolation, Structural Analysis and Biological Activity Assays of Biselisabethoxanes A and B: Two Dissymmetric Bis-Diterpenes from the Southwestern Caribbean Sea Gorgonian Coral Pseudopterogorgia elisabethae

Two novel dissymmetric diterpenoids, biselisabethoxanes A and B (1 and 2), were isolated from the hexane extracts of the gorgonian coral Pseudopterogorgia elisabethae. Biselisabethoxane A (1) represents the first example of a marine-derived C₄₀ dimer made of two distinct diterpene fragments, whereas biselisabethoxane B (2) is a fused heterodimer stemming from coupling of two amphilectane-based fragments. The structures of 1 and 2 were elucidated based on 1D and 2D NMR spectral data analysis. The molecular structure of 1 was subsequently confirmed by X-ray crystallographic analysis. When evaluated for their inhibitory effects in a series of well-established biological activity assays the isolated compounds were shown to moderately inhibit the growth of Mycobacterium tuberculosis.

Biogenetic and biomimetic synthesis of natural bisditerpenoids: hypothesis and practices

Covering: up to March 2022Bisditerpenoids, or diterpenoid dimers, are a group of natural products with high structural variance, deriving from homo- or hetero-dimeric coupling of two diterpenoid units. They usually possess complex architectures resulting from the diversity of monomeric diterpenoids as building blocks and the dimerization processes. These compounds have attracted the attention of synthetic and biological scientists owing to the rarity of their natural origin and their significant biological activities. Herein, we provide a review highlighting some of the interesting bisditerpenoids reported since 1961 and showcase the chemical diversity in both their structures and biosynthesis, as well as their biological functions. This review focuses on the biosynthetic dimerization pathways of interesting molecules and their biomimetic synthesis, which may act as useful inspiration for the discovery and synthesis of more bisditerpenoids and further pharmacological investigations.

A review of the phytochemistry, ethnopharmacology and biological activities of Teucrium genus (Germander)

Teucrium L (Lamiaceae) is mainly distributed in the Mediterranean area. A comprehensive survey in the electronic databases (during 2000-2020 years) with keywords of 'Teucrium' and 'Germander' showed that chemical analyses are available for 27 species, with sesquiterpenoids, iridoids, di and triterpenoids, and phenolic compounds as identified structures. The neo-clerodane diterpenoids as potential chemotaxonomic markers were the main compounds of this genus. As a result, Italy and Turkey have good attempts at phytochemical analysis. The pharmacological activities of different species including antioxidant, cytotoxic activity, antidiabetic, antimicrobial, anti-inflammatory and anti-insect have been summarized. Teucrium polium and Teucrium chamaedrys mainly have been used in digestive problems and diabetes in traditional medicine. Evidence-based clinical trials are needed to confirm the therapeutic properties of this genus. As well to the popularity of Asian and Anatolian species as ingredients in contemporary medicines and products, further research is required in comparison to European species.

Stereocontrolled Radical Bicyclizations of Oxygenated Precursors Enable Short Syntheses of Oxidized Abietane Diterpenoids

The power of cation-initiated cyclizations of polyenes for the synthesis of polycyclic terpenoids cannot be overstated. However, a major limitation is the intolerance of many relevant reaction conditions toward the inclusion in the substrate of polar functionality, particularly in unprotected form. Radical polycyclizations are important alternatives to bioinspired cationic variants, in part owing to the range of possible initiation strategies, and in part for the functional group tolerance of radical reactions. In this article, we demonstrate that Co-catalyzed MHAT-initiated radical bicyclizations are not only tolerant of oxidation at virtually every position in the substrate, oftentimes in unprotected form, but these functional groups can also contribute to high levels of stereochemical control in these complexity-generating transformations. Specifically, we show the effects of protected or unprotected hydroxy groups at six different positions and their impact on stereoselectivity. Further, we show how multiply oxidized substrates perform in these reactions, and finally, we document the utility of these reactions in the synthesis of three aromatic abietane diterpenoids.

An In Vitro Evaluation of the Molecular Mechanisms of Action of Medical Plants from the Lamiaceae Family as Effective Sources of Active Compounds against Human Cancer Cell Lines

It is predicted that 1.8 million new cancer cases will be diagnosed worldwide in 2020; of these, the incidence of lung, colon, breast, and prostate cancers will be 22%, 9%, 7%, and 5%, respectively according to the National Cancer Institute. As the global medical cost of cancer in 2020 will exceed about $150 billion, new approaches and novel alternative chemoprevention molecules are needed. Research indicates that the plants of the Lamiaceae family may offer such potential. The present study reviews selected species from the Lamiaceae and their active compounds that may have the potential to inhibit the growth of lung, breast, prostate, and colon cancer cells; it examines the effects of whole extracts, individual compounds, and essential oils, and it discusses their underlying molecular mechanisms of action. The studied members of the Lamiaceae are sources of crucial phytochemicals that may be important modulators of cancer-related molecular targets and can be used as effective factors to support anti-tumor treatment.

Anti-inflammatory sesquiterpenoids from the Traditional Chinese Medicine Salvia plebeia: Regulates pro-inflammatory mediators through inhibition of NF-κB and Erk1/2 signaling pathways in LPS-induced Raw264.7 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Salvia plebeia R. Brown, a traditional Chinese medicinal herb, has been used to treat inflammatory diseases such as cough, hepatitis, and diarrhea for a long history.

AIM OF THE STUDY

The aim of the present study was to isolate and identify potential anti-inflammatory agents from the herb of S. plebeia, which may have contributed to its folk pharmacological use in the treatment of inflammatory diseases.

MATERIAL AND METHODS

The aerial parts of S. plebeia were extracted with 95% ethanol and separated by silica gel, RP-C₁₈, Sephadex LH-20, and HPLC. The structures of the isolated compounds were elucidated by extensive spectroscopic analysis (MS, NMR, and X-ray). Anti-inflammatory activities of all compounds were evaluated by the model of LPS-induced up-regulated of NO in Raw264.7 macrophages. The expression levels of cytokine (TNF-α) and proteins (iNOS and COX-2) were assessed by ELISA kit and Western blotting analysis, respectively. Furthermore, the influences of salviplenoid A (1) on NF-κB and MAPK signaling pathways were determined by Western blotting analysis and immunofluorescence assay.

RESULTS

Six new (1-6, salviplenoids A-F) and ten known (7-16) sesquiterpenoids were isolated from the herb of S. plebeia. The absolute configurations of compounds 1, 2, and 7 were determined by X-ray diffraction. The new eudesmane-type sesquiterpenoid, salviplenoid A (1), significantly decreased the release of NO and TNF-α and the expression of proteins iNOS and COX-2. In addition, the biochemical mechanistic study indicated that 1 regulated the NF-κB dependent transcriptional activity through inhibiting the nuclear translocation of p50/p65 dimer and decreasing the phosphorylation of IκB and Erk1/2.

CONCLUSIONS

Among all sesquiterpenoids isolated from S. plebeian, the new salviplenoid A (1) exhibited the most potent anti-inflammatory activity in LPS-induced Raw264.7 cells via inhibition of NF-κB and Erk1/2 signaling pathways.

Anti-inflammatory Activity of Eudesmane-Type Sesquiterpenoids from Salvia plebeia

Nine new sesquiterpenoid lactones and 11 known analogues were isolated from the aerial parts of Salvia plebeia R.Br. Their structures were elucidated via HRESIMS and NMR data, and their absolute configurations were defined via electronic circular dichroism data, X-ray crystallographic analysis, and the modified Mosher's ester method. Compounds 1-20 were investigated for their ability to inhibit LPS-stimulated nitric oxide production in murine macrophage cells. Of the isolates, epi-eudebeiolide C (20) showed the highest inhibitory effect (IC₅₀ of 17.9 μM). mRNA and protein expression of inducible nitric oxide synthase (iNOS), but not that of cyclooxygenase-2 (COX-2), was dose-dependently decreased by 20 in LPS-activated RAW 264.7 cells. Based on a mechanistic study involving the nuclear factor-κB (NF-κB) signaling pathway, the anti-inflammatory effect of 20 was attributed to NF-κB activation blockade via inhibition of NF-κB (IκB) phosphorylation. Therefore, 20 might be a potential candidate for relieving inflammatory diseases.

Diterpenes and Their Derivatives as Potential Anticancer Agents

As therapeutic tools, diterpenes and their derivatives have gained much attention of the medicinal scientists nowadays. It is due to their pledging and important biological activities. This review congregates the anticancer diterpenes. For this, a search was made with selected keywords in PubMed, Science Direct, Web of Science, Scopus, The American Chemical Society and miscellaneous databases from January 2012 to January 2017 for the published articles. A total 28, 789 published articles were seen. Among them, 240 were included in this study. More than 250 important anticancer diterpenes and their derivatives were seen in the databases, acting in the different pathways. Some of them are already under clinical trials, while others are in the nonclinical and/or pre-clinical trials. In conclusion, diterpenes may be one of the lead molecules in the treatment of cancer. Copyright © 2017 John Wiley & Sons, Ltd.

Diterpenoids of terrestrial origin

This review covers the isolation and chemistry of diterpenoids from terrestrial as opposed to marine sources and includes labdanes, clerodanes, pimaranes, abietanes, kauranes, cembranes and their cyclization products. The literature from January to December, 2015 is reviewed.