Kujigamberol, a new dinorlabdane diterpenoid isolated from 85million years old Kuji amber using a biotechnological assay

Sulfurized diterpenoids in amber as diagenetic indicators of sulfate-reducing processes in past depositional environments

Two novel compounds isolated from an amber sample from the Santonian of Piolenc (Vaucluse, SE France) were identified using nuclear magnetic resonance and high-resolution mass spectrometry as sulfurized analogues of diterpenic acids from the isopimaric series originating from ancient conifers possibly related to the Cupressaceae family. These two compounds are members of a diterpenoid series corresponding to early diagenetic transformation products of resin diterpenoids. They were likely formed once plant resin comes into contact with reduced sulfur species originating from bacterial sulfate reduction occurring in anaerobic settings such as mangroves or marshes. They represent the first evidence of sulfurization processes affecting plant resin prior to diagenetic transformation into amber. Given their mode of formation, these compounds may be used as indicators of sulfate-reducing processes in past depositional environments.

Protective Effect of Amber Extract on Human Dopaminergic Cells against 6-Hydroxydopamine-Induced Neurotoxicity

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disease, after Alzheimer’s disease. In our previous study, we found that amber—a fossilized plant resin—can protect cells from apoptosis by decreasing the generation of reactive oxygen species (ROS). In this study, we focused on the effect of amber on 6-hydroxydopamine-induced cell apoptosis in the human neuroblastoma cell line SHSY5Y (one model for PD). Initially, we determined the protective effect of amber on the PD model. We found that amber extract has a protective effect against 6-hydroxydopamine-induced cell apoptosis. The decrease in ROS, cleaved caspase-3, pERK, and extracellular signal-regulated kinase (ERK) protein levels confirmed that amber extract decreases apoptosis via the ROS-mediated ERK signaling pathway. Furthermore, we determined the effects of amber extract on autophagy. The results showed that amber extract increased the levels of LC3II and Beclin-1, suggesting that amber extract can protect neuronal cells against 6-hydroxydopamine-induced cell apoptosis by promoting autophagy.

Anti-inflammatory activities of amber extract in lipopolysaccharide-induced RAW 264.7 macrophages

Amber is a type of fossil tree resin with several bioactive properties and has been traced in traditional medicines used in Russia and China. However, its anti-inflammatory activities are poorly characterized. Here, the anti-inflammatory effects of the extract of amber mined from Kaliningrad, Russia was investigated in lipopolysaccharide (LPS)-induced RAW 264.7 cells. The effect of the amber extract on cell viability was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. Further, its effects on the production of intracellular reactive oxygen species (ROS), NO, and inflammatory cytokines were assessed by 2',7'-dichlorodihydrofluorescein diacetate staining, Griess test, and cytokine enzyme-linked immunosorbent assays, respectively. Western blotting and real-time reverse transcription-polymerase chain reaction analysis were performed to assess the mRNA and protein expression levels of the inflammatory cytokines, including tumor necrosis factor-alpha (TNF-α) interleukin-6 (IL-6), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). The translocation of the nuclear factor-kappa B (NF-κB) p65 subunit was observed by immunofluorescent staining. Amber extract negatively regulated the LPS-induced differentiation of RAW 264.7 cells to dendritic-like cells and reduced the LPS-induced increase in ROS and NO levels. It also reduced the level of mRNA and protein expressions of TNF-α, IL-6, COX-2, and iNOS in LPS-induced RAW 264.7 macrophages, in a dose-dependent manner. Furthermore, amber extract suppressed the nuclear translocation of the NF-κB p65 subunit. These findings suggest that the potent anti-inflammatory effect of the amber extract is mediated by the inhibition of the NF-κB p65 signaling pathway. Collectively, this study renders amber extract as a potential pharmacological alternative to treat inflammation-related diseases.

Inhibition of melanin production and promotion of collagen production by the extract of Kuji amber

Kuji amber is fossilized tree resin of the Late Cretaceous in Japan. In this study, new biological activities of ethanol extract of Kuji amber (EtOH ext.) and supercritical carbon dioxide fluid extract of Kuji amber (scCO2 ext.) were examined. Both EtOH ext. and scCO2 ext. inhibited melanin production in B16 mouse melanoma cells and promoted collagen production in human skin fibroblast SF-TY cells. The scCO2 ext. had more potent activity than that of EtOH ext. and may depend on the efficiency of the extraction. The main new biologically active compound in Kuji amber, kujigamberol had no activities against melanin production, however, it promoted collagen production at low concentrations. A biologically active compound having a different structure, spirolactone norditerpenoid, showed both the inhibition activity against melanin production and the promotion activity of collagen production in a dose dependent manner. EtOH ext. and scCO2 ext., which include both kujigamberol and spirolactone norditerpenoid, have not only anti-allergy activity, but also inhibit melanin production and promote collagen production.

A novel Ca2+-signal transduction inhibitor, kujigamberol C, isolated from Kuji amber

A novel labdane type diterpenoid, 15-nor-8-labden-13-ol, named kujigamberol C, was isolated from Kuji amber using a modified isolation method to increase the yield of biologically active compounds. The structure was determined using HREIMS, 1D and 2D NMR. Kujigamberol C showed growth-restoring activity against mutant yeast via Ca2+-signal transduction.

Kujigamberoic acid A, a carboxylic acid derivative of kujigamberol, has potent inhibitory activity against the degranulation of RBL-2H3 cells

The aldehyde and carboxylic acid derivatives of kujigamberol were synthesized using pyridinium dichromate (PDC). The carboxylic acid derivative exhibited lower cytotoxicity and inhibited the degranulation of rat basophilic leukemia-2H3 (RBL-2H3) cells stimulated by thapsigargin more than kujigamberol. The carboxylic acid derivative was detected and isolated from the methanol extract of Kuji amber (MEKA) by the modified isolation procedure. Thus, it has been named as kujigamberoic acid A.

Isolation of yeast Ca2+ signal transduction inhibitors from the Early Cretaceous Burmese amber

Two kinds of biologically active compounds were isolated from the MeOH extract of the Early Cretaceous Burmese amber [99 million years ago (Ma)], which is older than the K-Pg boundary (65 Ma). These compounds had inhibitory activity against the hypersensitive mutant yeast strain (zds1∆ erg3∆ pdr1∆ pdr3∆) with respect to Ca²⁺ signal transduction. They were identified as 16,17-bisnordehydroabietic acid (1) and 16,17-bisnorcallitrisic acid (2), respectively, on the basis of spectral analyses including HREIMS, 1D, and 2D NMR. Both have faint growth restoring activities around the clear inhibition zone against the mutant yeast on the 0.31-0.16 μg/spot. This is the first report of direct structural elucidation of 1 and 2 and the biologically active compounds derived from Burmese amber.

Isolation of a spirolactone norditerpenoid as a yeast Ca2+ signal transduction inhibitor from Kuji amber and evaluation of its effects on PPM1A activity

A different type of biologically active compound from Kuji amber (Late Cretaceous, Japan) before the K-Pg boundary [65 million years ago (Ma)] was isolated based on the growth-restoring activity of a mutant yeast involving Ca²⁺ signal transduction. It was identified as a spirolactone norditerpenoid, (4R*, 5S*, 8R*, 9R*, 10S*)-14,15,16,19-tetranor-labdan-13,9-olide (1) from spectral analyses with high-resolution electron ionization mass spectrometry (HREIMS), 1D and 2D nuclear magnetic resonance (NMR). Although the planar structure of 1 is known as an artificial derivative from marrubiin, it was isolated as a natural product from Kuji amber and its structure was elucidated for the first time. It had a growth-restoring activity against the mutant yeast through the direct or indirect inhibition of calcineurin activity [protein phosphatase, Mg²⁺/Mn²⁺-dependent 1A (PPM1A) activation]. Furthermore, the compound had potent inhibitory effect against the degranulation of rat basophilic leukemia 2H3 (RBL-2H3) cells.

Kujigamberol interferes with pro-inflammatory cytokine-induced expression of and N-glycan modifications to cell adhesion molecules at different stages in human umbilical vein endothelial cells

Kujigamberol is the norlabdane compound isolated from Kuji amber and has recently been shown to prevent Ca²⁺-signal transduction and exert anti-allergy effects in vitro and in vivo. However, the anti-inflammatory activities of kujigamberol remain unclear. In the present study, we investigated the biological activities of kujigamberol on cell adhesion molecules expressed on human umbilical vein endothelial cells (HUVEC) in response to pro-inflammatory cytokines. Kujigamberol decreased the molecular weight of intercellular adhesion molecule-1 (ICAM-1) by altering N-glycan modifications. In contrast to ICAM-1, kujigamberol reduced the interleukin-1α- or tumor necrosis factor α-induced expression of vascular cell adhesion molecule-1 (VCAM-1) and E-selectin at the mRNA and protein levels. Kujigamberol B, but not kujiol A, decreased the molecular weight of the ICAM-1 protein. Kujigamberol moderately inhibited yeast α-glucosidases, whereas it was only weakly inhibited by kujigamberol B and more weakly by kujiol A. Three compounds did not inhibit Jack bean α-mannosidases. The present results reveal new biological activities of kujigamberol, which interfere with the pro-inflammatory cytokine-induced expression of and N-glycan modifications to cell adhesion molecules in HUVEC.

Ca2+-Signal Transduction Inhibitors, Kujiol A and Kujigamberol B, Isolated from Kuji Amber Using a Mutant Yeast

A podocarpatriene and a labdatriene derivative, named kujiol A [13-methyl-8,11,13-podocarpatrien-19-ol (1)] and kujigamberol B [15,20-dinor-5,7,9-labdatrien-13-ol (2)], respectively, were isolated from Kuji amber through detection with the aid of their growth-restoring activity against a mutant yeast strain ( zds1Δ erg3Δ pdr1Δ pdr3Δ), which is known to be hypersensitive with respect to Ca²⁺-signal transduction. The structures were elucidated by spectroscopic data analysis. Compounds 1 and 2 are rare organic compounds from Late Cretaceous amber, and the mutant yeast used seems useful for elucidating a variety of new compounds from Kuji amber specimens, produced before the K-Pg boundary.

A new α-pyrone metabolite from a mangrove plant endophytic fungus, Fusarium sp

A new α-pyrone derivative, compound 2, and a known one, cladobotrin V, were isolated from the culture broth of the mangrove endophyte Fusarium sp. IM-37. Their structures were determined spectroscopically and compared with previously reported spectral data. Compound 2 restored the growth inhibition caused by hyperactivated Ca(2+)-signaling in mutant yeast.

Selected terpenoids from medicinal plants modulate endoplasmic reticulum stress in metabolic disorders

Objectives

The majority of research performed on cellular stress and apoptosis focuses on mitochondrial dysfunction; however, the importance of the endoplasmic reticulum dysfunction and the link to metabolic diseases has gained a substantial interest. This review focuses on the potential of terpenoids to influence endoplasmic reticulum stress and the possible role terpenoids play as the treatment of metabolic diseases.

Key findings

Metabolic diseases develop as a result of a cascade of cellular pathways. In most cases, cells are able to compensate for the disruption of the cellular homeostasis although the initiation of response pathways; however, chronic stress initiates apoptotic pathways. This reviewed (1) showed the importance of phytoterpenoids to influence endoplasmic reticulum (ER) stress and homeostasis, (2) showed how regulating ER stress affect the cell survival and death, and (3) highlighted some examples of how the progression of metabolic diseases can be influenced by ER.

Summary

Due to the substantial number of terpenoids that have been identified in literature, this review gave examples of 21 terpenoids that have been documented to have an effect on the different proteins associated with ER stress, how these plant terpenoids influence ER dysfunction and metabolic diseases such as diabetes, cancer, liver, and neurological diseases and parasitic infections.