oleoresins against multidrug-resistant bacteria

To evaluate the antibacterial, antibiofilm and antivirulence potential of the main diterpenes from Copaifera spp. oleoresins against multidrug-resistant (MDR) bacteria. Antimicrobial assays included determination of the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Inhibitory Concentration of Biofilm (MICB50), as well as synergistic and antivirulence assays for eight diterpenes against MDR. The tests revealed that two diterpenes (named 1 and 5) showed the best results, with MIC and MBC between 12.5 and 50 μg/mL against most MDR bacteria. These diterpenes exhibited promising MICB50 in concentration between 3.12-25 μg/mL but showed no synergistic antimicrobial activity. In the assessment of antivirulence activity, diterpenes 1 and 5 inhibited only one of the virulence factors evaluated (Dnase) produced by some strains of S. aureus at subinhibitory concentration (6.25 μg/mL). Results obtained indicated that diterpenes isolated from Copaifera oleoresin plays an important part in the search of new antibacterial and antibiofilm agents that can act against MDR bacteria.

Anti-biofilm and anti-inflammatory active diterpene isolated from the fruit of Xylopia benthamii R.E.Fr

Xylopia benthamii (Annonaceae) is a plant with limited phytochemical and pharmacological evidence. Thus, using LC-MS/MS, we performed exploratory analyses of the fruit extract of X. benthamii, resulting in the tentative identification of alkaloids (1-7) and diterpenes (8-13). Through the application of chromatography techniques with the extract of X. benthamii, two kaurane diterpenes were isolated, xylopinic acid (9) and ent-15-oxo-kaur-16-en-19-oic acid (11). Their structures were established using spectroscopy (NMR 1D/2D) and mass spectrometry. The isolated compounds were submitted to anti-biofilm analysis against Acinetobacter baumannii, anti-neuroinflammatory and cytotoxic activity in BV-2 cells. Compound 11 (201.75 µM) inhibited 35% of bacterial biofilm formation and high anti-inflammatory activity in BV-2 (IC50 = 0.78 µM). In conclusion, the results demonstrated that compound 11 was characterized for the first time with pharmacological potential in the development of new alternatives for studies with neuroinflammatory diseases.

Combinatorial biosynthesis in yeast leads to over 200 diterpenoids

Diterpenoids form a diverse group of natural products, many of which are or could become pharmaceuticals or industrial chemicals. The modular character of diterpene biosynthesis and the promiscuity of the enzymes involved make combinatorial biosynthesis a promising approach to generate libraries of diverse diterpenoids. Here, we report on the combinatorial assembly in yeast of ten diterpene synthases producing (+)-copalyl diphosphate-derived backbones and four cytochrome P450 oxygenases (CYPs) in diverse combinations. This resulted in the production of over 200 diterpenoids. Based on literature and chemical database searches, 162 of these compounds can be considered new-to-Nature. The CYPs accepted most substrates they were given but remained regioselective with few exceptions. Our results provide the basis for the systematic exploration of the diterpenoid chemical space in yeast using sequence databases.

Alzheimer's disease: In silico study of rosemary diterpenes activities

The global surge in Alzheimer's disease poses a significant public health concern. In response, we study the efficacy of carnosic acid and related abietane-type diterpenes extracted from rosemary as acetylcholinesterase (AChE) inhibitors. Our analyses, using in silico techniques, encompassed all the compounds within this extract. Through molecular docking, we explored how these compounds interact with the active site of the AChE protein. The docking scores, ranging from -5.560 Kcal/mol to -7.270 Kcal/mol, indicate robust binding affinities. Assessment of the ADME/T (Adsorption, Distribution, Metabolism, Excretion, and Toxicity) properties and pharmacokinetics of these compounds reveal favorable profiles for all the tested substances. These encouraging results suggest the potential of these compounds as candidates for further development to prevent and/or treat Alzheimer's disease. Among these compounds, we find rosmanol as the most likely candidate for further research and clinical trials to validate their efficacy.

Cytotoxic and antiviral activities of Jatropha variegata and Jatropha spinosa in relation to their metabolite profile

Jatropha variegata and Jatropha spinosa (family: Euphorbiaceae) are utilized in Yemeni traditional medicine to treat respiratory tract infection and in different skin conditions such as wound healing, as antibacterial and hemostatic. In this study, we evaluated the cytotoxicity and the antiviral activities of the methanolic J. variegata (leaves: Ext-1, stems: Ext-2, and roots: Ext-3), and J. spinosa extracts (aerial parts: Ext-4 and roots: Ext-5), in addition to their methylene chloride fractions of roots extracts (F-6 and F-7, respectively). All samples were tested against three human cancer cell lines in vitro (MCF-7, HepG2, and A549) and two viruses (HSV-2 and H1N1). Both plants showed significant cytotoxicity, among them, the methylene chloride fractions of roots of J. variegata (F-6) and J. spinosa roots (F-7) showed the highest activity on MCF-7 (IC50 = 1.4 and 1 μg/mL), HepG2 (IC50 = 0.64 and 0.24 μg/mL), and A549 (IC50 = 0.7 and 0.5 μg/mL), respectively, whereas the IC50 values of the standard doxorubicin were (3.83, 4.73, and 4.57 μg/mL) against MCF-7, HepG2, and A549, respectively. These results revealed that the roots of both plants are potential targets for cytotoxic activities. The in vitro results revealed potential antiviral activity for each of Ext-3, Ext-5, F-6, and F-7 against HVS-2 with IC50 of 101.23, 68.83, 4.88, 3.24 μg/mL and against H1N1 with IC50 of 51.29, 27.92, 4.24, and 3.06 μg/mL respectively, whereas the IC50 value of the standard acyclovir against HVS-2 was 83.19 μg/mL and IC50 value of the standard ribavirin against H1N1 was 52.40 μg/mL .The methanol extracts of the roots (Ext-3 and Ext-5) of both plants were characterized using UPLC/MS. A total of 73 metabolites were annotated, including fourteen diterpenoids, eleven flavonoids, ten phenolic acid conjugates, twelve fatty acids and their conjugates, five triterpenes and steroids, two sesquiterpenes, and six coumarins. The cytotoxicity and antiviral activities determined in the present work are explained by the existence of flavonoids, coumarins and diterpenes with commonly known cytotoxicity and antiviral activities.

Diterpenes stability of commercial blends of roasted and ground coffees packed in copolymer coupled with aluminium and eco-friendly capsules

Diterpenes are group of compounds of the terpenic fraction of roasted coffee and account for about 7-20 % (w/w) of the lipid fraction. Several parameters can influence their occurrence in coffee beans and beverages including species and post-harvest processing. Diterpenes in coffee have been studied extensively, but to the best of the authors' knowledge, there is no information in the literature on their stability over time. Coffee is a relatively stable product under optimal temperature, humidity and oxygen conditions. However, during storage it can undergo a series of chemical and physical reactions that alter its flavour and lead to rancidity, mainly due to the oxidative reactions that take place on the lipid fraction. In this study, the effect of long-term storage on the diterpene content of different commercial coffee blends and packaging is analysed and critically discussed. The Results show that the storage influences the internal environment of the capsules with an increase in moisture and a decrease in pH favouring more reactive conditions, especially for Eco capsules. Relative stability over time is observed for cafestol and kahweol. dehydro derivatives show a degradation up to T60 independently on the blends and packaging, which is not related to their precursors. The permeability of packaging and blends affect the modification of these components: while a drastic oxidation process takes place in Arabica eco compatible capsules (PC) when acidity and moisture increase, in Arabica/Robusta eco compatible capsules (IC) as well as in Arabica/Robusta and Arabica standard capsules (IS and PS) the peroxides tend to increase resulting in an autocatalytic propagation.

Cytotoxic activity and docking studies

From the bioactive extract of the euphorbiaceous Croton niveus Jacq., three previously unreported ent-rosane diterpenes have been isolated and characterized by conventional methods, in addition to the known compounds lupeol, cajucarinolide and some phytosterols. Two of the ent-rosane diterpenes displayed activity against HCT-15 and PC-3 cancer cell lines, and the results of docking calculations of these compounds with NF-κB and STAT3 receptors agreed with the proposed mode of action of diterpenes against PC-3 cells.

UPLC-QTOF-MS/MS-based metabolomic approach and gastroprotective effect of two chemotypes of Egletes viscosa (L.) less. against ethanol-induced gastric ulcer in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Egletes viscosa (L.) (macela) is a native wild herb that can be found in different states of northeastern Brazil. The infusions of its flower buds are traditionally used for the treatment of gastrointestinal disorders. E. viscosa possesses two chemotypes (named A and B), distinguishable by the composition of the essential oil from the flower buds. Although there are previous studies of the gastroprotective effect of the isolated constituents of E. viscosa, its infusions have not been investigated yet.

AIM OF THE STUDY

The present study aimed to evaluate and compare the chemical composition and the gastroprotective effect of flower bud infusions of E. viscosa from chemotype A (EVCA) and chemotype B (EVCB).

MATERIALS AND METHODS

Sixteen infusions were brewed with flower buds according to the traditional preparation mode and were analyzed through a UPLC-QTOF-MS/MS based metabolomic approach for determination of their metabolic fingerprints and quantification of bioactive compounds. Afterward, these data were analyzed by chemometric methods (OPLS-DA) for discrimination of the two chemotypes. Additionally, infusions of EVCA and EVCB (50, 100 and 200 mg/kg, p.o.) were evaluated on gastric ulcers induced by absolute ethanol (96%, 0.2 mL, p.o.) in mice. To elucidate the gastroprotective mechanisms, the effect of EVCA and EVCB on gastric acid secretion and gastric wall mucus was determined and the role of TRPV1 channels, prostaglandins, nitric oxide and K_ATP channels were assessed. Moreover, the oxidative stress-related parameters and the histological aspects of the stomach tissue were analyzed.

RESULTS

The chemotypes can be discriminated from each other using UPLC-QTOF-MS/MS chemical fingerprints. Both chemotypes presented similar chemical compositions, consisting basically of caffeic acid derivatives, flavonoids and diterpenes. The quantification of bioactive compounds demonstrated that chemotype A possesses more ternatin, tanabalin and centipedic than chemotype B. EVCA and EVCB (50, 100 and 200 mg/kg, p.o.) significantly decreased the severity of ethanol-induced gastric lesions, as shown by a reduction in histological alterations and leucocyte infiltration in gastric tissue. The gastroprotective mechanism of both infusions involves an antioxidant effect, maintenance of gastric mucus and reduction gastric secretion. Stimulation of endogenous prostaglandins and nitric oxide release, activation of TRPV1 channels, and K_ATP channels are also involved in the gastroprotection of the infusions.

CONCLUSION

The gastroprotective effect of EVCA and EVCB was equivalent and mediated through antioxidant and antisecretory actions, including the activation of TRPV1 receptors, stimulation of endogenous prostaglandins and nitric oxide, and opening of K_ATP channels. The presence of caffeic acid derivatives, flavonoids and diterpenes in both infusions is involved in mediating this protective effect. Our findings support the traditional use of infusions of E. viscosa for gastric disorders regardless of the chemotype.

An overview of the traditional use, phytochemistry, and biological activity of the genus Homalanthus

Homalanthus species are native to tropical Asia and the Pacific region. This genus, comprising 23 accepted species, received less scientific attention compared to other genera of the Euphorbiaceae family. Seven Homalanthus species, such as H. giganteus, H. macradenius, H. nutans, H. nervosus, N. novoguineensis, H. populneus, and H. populifolius, have been reported to treat various health problems in traditional medicine. Only a few Homalanthus species have been investigated for their biological activities, including antibacterial, anti-HIV, anti-protozoal, estrogenic, and wound-healing activities. From a phytochemical point of view ent-atisane, ent-kaurane, and tigliane diterpenoids, triterpenoids, coumarins, and flavonol glycosides were found to be characteristic metabolites of the genus. The most promising compound is prostratin, isolated from H. nutans, with anti-HIV activity and the ability to eradicate the HIV reservoir in infected patients by mechanism of protein kinase C (PKC) agonist. This review provides information on traditional usage, phytochemistry, and biological activity of the genus Homalanthus with the aim to delineate future research directions.

Andrographolide protects against doxorubicin-and arsenic trioxide-induced toxicity in cardiomyocytes

BACKGROUND

Andrographolide (AG) is a lactone diterpene with valuable biological activities. This in vitro study evaluated whether AG can protect cardiomyocytes under toxicities triggered with anti-cancer chemotherapeutic agents, doxorubicin (DOX) and arsenic trioxide (ATO).

METHODS AND RESULTS

H9C2 cells were pretreated with AG (0.5-10 µM) for 24 h and then exposed to DOX (1 μM) or ATO (35 μM) for another 24 h period. For determination of cell viability or cytotoxicity, MTT and lactate dehydrogenase (LDH) assay were used. Total oxidant and antioxidant capacities were estimated by determining hydroperoxides and ferric reducing antioxidant power (FRAP) levels. Real time-polymerase chain reaction was also used for quantitative evaluation of TLR4 gene expression. AG inhibited cardiomyocytes proliferation at the concentrations of more than 20 μM. However, it considerably enhanced cell viability and decreased cytotoxicity of DOX and ATO at the concentration range of 2.5-10 μM in MTT and LDH assays. AG significantly declined hydroperoxides concentration in ATO-treated cardiomyocytes and raised FRAP value in DOX- and ATO-treated cells. Furthermore, AG notably lessened TLR4 expression in H9C2 cells after exposure to DOX- and ATO.

CONCLUSION

In conclusion, these data presented that AG was able to reverse DOX- and ATO-induced cardiotoxicity in vitro. The cardiomyocyte protective activities of AG may be due to the decrease in TLR4 expression and total oxidant capacity and increase in total antioxidant capacity.

Chemical characteristics of the sesquiterpenes and diterpenes from Lauraceae family and their multifaceted health benefits: A review

Lauraceae is a large family with significant economic and medicinal value. Bioactive ingredients from Lauraceae plants have contributed greatly to medicines, food nutrients and fine chemical products. In recent years, quite a few sesquiterpenes and diterpenes with unique structures have been achieved from Lauraceae and their potential benefits are embodied in a wide range of health areas. To our knowledge, there is no review to summarizes these constituents and their biological effects systematically. This current work aims to classify and ascribe the structural types and bioactivities of the identified sesquiterpenes and diterpenes. Herein, a total of 362 sesquiterpenes and 69 diterpenes were comprehensively complied. The various bioactivities could be recognized as cytotoxicity, anti-proliferation and/or anti-apoptosis, anti-inflammation, anti-oxidation, anti-bacterium, etc. This updated data could serve as a catalysis of these sesquiterpenes and diterpenes for the future medical and industrial applications.

Chemical constituents and their anti-neuroinflammatory activities from the bark of Taiwan incense cedar, Calocedrus formosana

One undescribed C40 terpenoid, calomacroquinoic acid; four undescribed diterpenes, 5α,6α-epoxy-7α-hydroxyferruginol, 15-ethoxysugiol, 7-methoxy-6,7-secoabieta-8,11,13-triene-6,12-diol, and ethyl 7,8-secoabieta-11,14-dioxo-7-ate; two compounds isolated from Nature for the first time, 6β,7α-dihydroxyferruginol and 12-O-methyltaxochinon; and six known compounds were successfully identified from the bark of Taiwan incense cedar Calocedrus formosana. Structures of all isolates were elucidated by physical data (appearance, ultraviolet, infrared, specific rotation, and X-ray) and spectroscopic data (1D and 2D nuclear magnetic resonance, and high-resolution electron ionization mass spectrometry). The biosynthetic pathway of calomacroquinoic acid is also described in the current study. Nitric oxide production in lipopolysaccharide (LPS)-stimulated BV-2 microglia cells was inhibited by 6,7-dehydroferruginol, 7α,11-dihydroxy-12-methoxy-8,11,13-abietriene, and trans-communic acid. Altogether, the bark of C. formosana possessed several potential natural therapeutics against inflammation-related neuronal diseases.

Chemical characterization and antioxidant potential of ecuadorian propolis

The chemical composition and the antioxidant potential of Ecuadorian propolis samples (n = 19) collected in different provinces were investigated. HPLC-DAD-ESI/MSⁿ and GC-EI-MS analysis of the methanol extracts enabled us to define six types of Ecuadorian propolis based on their secondary metabolite composition. 68 compounds were identified, 59 of which are reported for the first time in Ecuadorian propolis. The detected compounds include flavonoids, diterpenes, triterpenes, organic acid derivatives, alkylresorcinol derivatives and nemorosone. Plants belonging to genera Populus, Mangifera and Clusia seemed to be vegetable sources employed by bees to produce Ecuadorian propolis. Total phenolic content and antioxidant activity of propolis extracts were determined by the Folin-Ciocalteu assay and 2,2-diphenyl-1-picrylhydrazyl and ferric reducing/antioxidant potential assays, respectively. As expected, the variable chemical composition affected the differences in terms of antioxidant potential.

Assessment of antioxidant and antiparkinsonian potential of a new diterpene isolated from Croton argyrophylloides

Oxidative stress is related to health problems including neurological and neurodegenerativedisturbs, such as Parkinson's disease. Natural compounds are reported as source of antioxidant molecules. Therefore, this study aimed to analyze the antioxidant and neuroprotective potential of a new diterpene isolated from C. argyrophylloides (MP-1). Male Wistar rats (250-300 g) were used to evaluate MP-1 antiparkinsonian potential through neurodegenerative model induced by the neurotoxin 6-hydroxydopamine (21 μg). On the 14th day, animals were submitted to behavioral tests and on the 15th day, brain areas were dissected to neurochemical analyzes. MP-1 demonstrated a high antioxidant capacity in vitro and decreased the parkinsonian effects, such as behavioral changes, motor alterations, and body weight loss. MP-1 was also able to control the upregulated levels of nitrosative stress and lipid peroxidation. These findings suggest MP-1 as a diterpene with high antioxidant capacity which might be used to development of new approach against Parkinson's disease.

Synthesis and evaluation of diterpenic Mannich bases as antiviral agents against influenza A and SARS-CoV-2

A chemical library was constructed based on the resin acids (abietic, dehydroabietic, and 12-formylabietic) and its diene adducts (maleopimaric and quinopimaric acid derivatives). The one-pot three-component CuCl-catalyzed aminomethylation of the abietane diterpenoid propargyl derivatives was carried out by formaldehyde and secondary amines (diethylamine, pyrrolidine, morpholine, and homopiperazine). All compounds were tested for cytotoxicity and antiviral activity against influenza virus A/Puerto Rico/8/34 (H1N1) in MDCK cells and SARS-CoV-2 pseudovirus in BHK-21-hACE2 cells. Among 21 tested compounds, six derivatives demonstrated a selectivity index (SI) higher than 10, and their IC₅₀ values ranged from 0.19 to 5.0 μM. Moreover, two derivatives exhibited potent anti-SARS-CoV-2 infection activity. The antiviral activity and toxicity strongly depended on the nature of the diterpene core and heterocyclic substituent. Compounds 12 and 21 bearing pyrrolidine moieties demonstrated the highest virus-inhibiting activity with SIs of 128.6 and 146.8, respectively, and appeared to be most effective when added at the time points 0-10 and 1-10 h of the viral life cycle. Molecular docking and dynamics modeling were adopted to investigate the binding mode of compound 12 into the binding pocket of influenza A virus M2 protein. Compound 9 with a pyrrolidine group at C20 of 17-formylabietic acid was a promising anti-SARS-CoV-2 agent with an EC₅₀ of 10.97 µM and a good SI value > 18.2. Collectively, our data suggested the potency of diterpenic Mannich bases as effective anti-influenza and anti-COVID-19 compounds.

Cytotoxicity, apoptosis inducing activity and Western blot analysis of tanshinone derivatives from Stachys parviflora on prostate and breast cancer cells

Cytotoxic activities of methanolic crude extract of Stachys parviflora (Lamiaceae family) and its sub-fractions were primarily evaluated against human breast adenocarcinoma (MCF-7 and MDA-MB-231) and prostate (PC3) cell lines. The methanolic extract exhibited the highest activity, and was chosen for the isolation procedure. Four diterpenoid quinones, namely miltirone [1], tanshinone IIA [2], 1-hydroxy-tanshinone IIA [3], and cryptotanshinone [4] were isolated. Notably, this is the first report on the isolation and/or characterization of the mentioned diterpenoids from the Stachys genus. In this study, 1-hydroxy-tanshinone IIA [3] displayed the highest cytotoxicity among the isolated compounds. The mechanism of the cytotoxicity of methanolic extract and isolated compounds was further investigated by the utilization of propidium iodide staining (PI) assay. The results showed that the methanolic extract and 1-hydroxy-tanshinone IIA [3] enhanced DNA fragmentation in PC3 and MCF-7 cells. Moreover, the western blotting analysis demonstrated increasing and decreasing protein levels of Bax and Bcl2, respectively, and cleaved poly ADP-ribose polymerase (PARP). Further bioassay-guided phytochemical assessments of S. parviflora can be suggested as a promising approach for discovering potent bioactive secondary metabolites.

Diterpenoids with α-glucosidase inhibitory activities from the fruits of Vitex trifolia Linn

Viticis Fructus, known as "Man-jing-zi", are the fruits of the traditional Chinese medicine Vitex trifolia Linn. and its variant Vitex trifolia Linn. var. simplicifolia. These fruits are used as folk medicines to treat various diseases. Although V. trifolia is useful for treating diabetes, the antidiabetic effect of its purified constituents is still under investigation. The phytochemical investigation on the ethanol extract of the fruits of V. trifolia yielded four new labdane diterpenoids vitetrolins A-D (1-4), together with seven (5-11) known analogs. The structures of these compounds were elucidated by spectroscopy techniques and the absolute configuration of 4 was determined by electronic circular dichroism (ECD) calculations. The isolated diterpenoids were evaluated for their α-glucosidase inhibitory activities. Compounds 5, 6, 8, and 9 exhibited moderate inhibitory activities against α-glucosidase with IC₅₀ values ranging from 44.9 ± 6.1 to 70.5 ± 5.5 μM.

Abietane diterpenes from Abies spectabilis and their anti-pancreatic cancer activity against the MIA PaCa-2 cell line

An ethanolic extract of the stem of Abies spectabilis exhibited strong cytotoxicity against MIA PaCa-2 human pancreatic cancer cells preferentially under nutrient-deprived conditions. Therefore, phytochemical investigation of this bioactive extract was carried out, and that led the isolation of ten compounds (1-10) including a new abietane-type diterpene (1). The structure of the new compound (1) was elucidated by combined spectroscopic techniques, including HRFABMS, NMR and quantum ECD calculation. All the isolated compounds were evaluated for their efficacy against MIA PaCa-2 human pancreatic cancer cell line by employing an anti-austerity strategy. Among the tested compounds, dehydroabietinol (5) displayed the most potent activity with a PC50 value of 6.6 μM. Dehydroabietinol (5) was also found to retard the MIA PaCa-2 cell migration under normal nutrient-rich conditions displaying its anti-metastatic potential. Investigation on the mechanism suggested that dehydroabietinol (5) is an inhibitor of the key cancer cell survival Akt/mTOR/autophagy signaling pathway.

Potential of Diterpenes as Antidiabetic Agents: Evidence from Clinical and Pre-Clinical Studies

Diterpenes are a diverse group of structurally complex natural products with a wide spectrum of biological activities, including antidiabetic potential. In the last 25 years, numerous diterpenes have been investigated for antidiabetic activity, with some of them reaching the stage of clinical trials. However, these studies have not been comprehensively reviewed in any previous publication. Herein, we critically discussed the literature on the potential of diterpenes as antidiabetic agents, published from 1995 to September, 2021. In the period under review, 427 diterpenes were reported to have varying degrees of antidiabetic activity. Steviol glycosides, stevioside (1) and rebaudioside A (2), were the most investigated diterpenes with promising antidiabetic property using in vitro and in vivo models, as well as human subjects. All the tested pimaranes consistently showed good activity in preclinical evaluations against diabetes. Inhibitions of α-glucosidase and protein tyrosine phosphatase 1B (PTP 1B) activities and peroxisome proliferator-activated receptors gamma (PPAR-γ) agonistic property, were the most frequently used assays for studying the antidiabetic activity of diterpenes. The molecular mechanisms of action of the diterpenes include increased GLUT4 translocation, and activation of phosphoinositide 3-kinase (PI3K) and AMP-activated protein kinase (AMPK)-dependent signaling pathways. Our data revealed that diterpenes hold promising antidiabetic potential. Stevioside (1) and rebaudioside A (2) are the only diterpenes that were advanced to the clinical trial stage of the drug discovery pipeline. Diterpenes belonging to the abietane, labdane, pimarane and kaurane class have shown promising activity in in vitro and in vivo models of diabetes and should be further investigated.

Genomic and transcriptomic inventory of membrane transporters in coffee: Exploring molecular mechanisms of metabolite accumulation

The genus Coffea (Rubiaceae) encompasses a group of perennial plant species, including a commodity crop from which seeds are roasted, ground, and infused to make one of the most appreciated beverages in the world. As an important tropical crop restricted to specific regions of the world, coffee production is highly susceptible to the effects of environmental instabilities (i.e., local year-to-year weather fluctuations and global climate change) and threatening pest pressures, not to mention an increasing quality rigor by consumers in industrialized countries. Specialized metabolites are substances that largely affect plant-environment interactions as well as how consumers experience agricultural products. Membrane transporters are key targets, albeit understudied, for understanding and tailoring the spatiotemporal distribution of specialized metabolites as they mediate and control molecular trafficking and substance accumulation. Therefore, we analyzed the transportome of C. canephora encoded within the 25,574 protein-coding genes annotated in the genome of this species and identified 1847 putative membrane transporters. Following, we mined 152 transcriptional profiles of C. canephora and C. arabica and performed a comprehensive co-expression analysis to identify transporters potentially involved in the accumulation of specialized metabolites associated with beverage quality and bioactivity attributes. In toto, this report points to an avenue of possibilities on Coffea genomic and transcriptomic data mining for genetic breeding strategies, which can lead to the development of new, resilient varieties for more sustainable coffee production systems.

Potential of diterpene compounds as antivirals, a review

Viruses cause widely transmitted diseases resulting in pandemic conditions. Currently, the world is being hit by the Covid-19 pandemic caused by the SAR-CoV-2 infection. Countries in the world are competing to develop antivirals to overcome this problem. Diterpene compounds derived from natural ingredients (plants, corals, algae, fungi, sponges) and synthesized products have potential as antivirals. This article summarizes the different types of diterpenes such as daphnane, tiglilane, kaurane, abietane, pimarane, labdane, dollabelane, jatrophane, dolastane, prenylated guaiane, tonantzitlolone, casbane, have antivirals activity such as targeting HIV, Coxsackie virus, herpes virus, hepatitis virus, influenza virus, Chikungunya virus, Zika virus, dengue virus, and SARS-CoV. Some compounds such as andrographolide and its derivatives show promising activity in inhibiting the influenza virus. Additionally, compounds such as pineolidic acid, forskolin, sugiol, and many other diterpene compounds showed anti-SAR-CoV activity. The diterpene compound class's high antivirals potential does not rule out the possibility that these compounds can also act as anti-SAR-CoV-2 drugs in the future.

New lobane-type diterpenoids from the Xisha soft coral Sinularia polydactyla

Lobane-type diterpenoids are not frequently discovered from marine soft corals. In this paper, three new lobane type diterpenes, 13-methoxyloba-8,10,15(16),17(18)-tetraene (1), 8,10,13(15)Z,16E-lobatetraene (2) and 19-hydroxy-lobatetraene (3), and a new natural compound, 17,18-epoxyloba-16-acetoxy-8,10,13(15)-trien (4), co-occurring with a known related diterpenoid, 18-methoxyloba-8,10,13(15),16(17)-tetraene (5), were isolated from the South China Sea soft coral Sinularia polydactyla. The structures of new compounds were determined by extensive spectroscopic analysis and by comparison with those reported in the literature. In bioassay, all the isolates were inactive on antibacterial, PTP1B inhibitory, and immunological activities. This study increased the chemical diversity of marine diterpenoids.

Chemometric-enhanced metabolic profiling of five Pinus species using HPLC-MS/MS spectrometry: Correlation to in vitro anti-aging, anti-Alzheimer and antidiabetic activities

Detailed metabolic profiling of needles of five Pinus species was investigated using complementary HPLC-MS/MS techniques together with supervised and unsupervised chemometric tools. This resulted in putative identification of 44 compounds belonging to flavonoids, phenolics, lignans, diterpenes and fatty acids. Unsupervised principal component analysis showed that differences were maintained across the metabolites characteristic of each Pinus species, are mainly related to di-O-p-coumaroyltrifolin, p-coumaroyl quinic acid derivative, arachidonic acid, hydroxypalmitic acid, isopimaric acid and its derivative. A supervised Partial Least Squares regression analysis was performed to correlate HPLC-MS/MS profiles with the variation observed in the in vitro anticholinesterase, antiaging and anti-diabetic potential. All investigated Pinus extracts exerted their antiaging activity via increasing telomerase and TERT levels in normal human melanocytes cells compared to the control (untreated cells). Profound inhibition activities of acetylcholinesterase and dipeptidyl peptidase-4 were also observed with P. pinea and P. canariensis extracts having comparable antidiabetic activities to sitagliptin as a standard antidiabetic drug. Our findings suggested that pine needles are a good source of phenolics and diterpenoids that have possible health promoting activities in management and alleviation of diabetic conditions and Alzheimer disease.

Apoptosis-like cell death upon kinetoplastid induction by compounds isolated from the brown algae Dictyota spiralis

BACKGROUND

The in vitro activity of the brown seaweed Dictyota spiralis against both Leishmania amazonensis and Trypanosoma cruzi was evaluated in a previous study. Processing by bio-guided fractionation resulted in the isolation of three active compounds, classified as diterpenes. In the present study, we performed several assays to detect clinical features associated to cell death in L. amazonensis and T. cruzi with the aim to elucidate the mechanism of action of these compounds on parasitic cells.

METHODS

The aims of the experiments were to detect and evaluate specific events involved in apoptosis-like cell death in the kinetoplastid, including DNA condensation, accumulation of reactive oxygen species and changes in ATP concentration, cell permeability and mitochondrial membrane potential, respectively, in treated cells.

RESULTS

The results demonstrated that the three isolated diterpenes could inhibit the tested parasites by inducing an apoptosis-like cell death.

CONCLUSIONS

These results encourage further investigation on the isolated compounds as potential drug candidates against both L. amazonensis and T. cruzi.

Disclosing the potential of eleganolone for Parkinson's disease therapeutics: Neuroprotective and anti-inflammatory activities

The treatment of Parkinson´s disease (PD) has benefited from significant advances resulting from the increasing research efforts focused on new therapeutics. However, the current treatments for PD are mostly symptomatic, alleviating disease symptoms without reversing or retarding disease progression. Thus, it is critical to find new molecules that can result in more effective treatments. Within this framework, this study aims to evaluate the neuroprotective and anti-inflammatory effects of three compounds (eleganolone, eleganonal and fucosterol) isolated from the brown seaweed Bifurcaria bifurcata. In vitro neuroprotective effects were evaluated on a PD cellular model induced by the neurotoxin 6-hydroxydopamine (6-OHDA) on SH-SY5Y human cells, while lipopolysaccharide (LPS) - stimulated RAW 264.7 macrophages were used to evaluate the anti-inflammatory potential. Additionally, the underlying mechanisms of action were also investigated. Compounds were isolated by preparative chromatographic methods and their structural elucidation attained by NMR spectroscopy. Among the tested compounds, eleganolone (0.1-1 µM; 24 h) reverted the neurotoxicity induced by 6-OHDA in about 20%. The neuroprotective effects were mediated by mitochondrial protection, reduction of oxidative stress, inflammation and apoptosis, and inhibition of NF-kB pathway. The results suggest that eleganolone may provide advantages in the treatment of neurodegenerative conditions and, therefore, should be considered for future preclinical studies.

Primary and Secondary Metabolite Profiles of Lodgepole Pine Trees Change with Elevation, but Not with Latitude

Climate change has a large influence on plant functional and phenotypic traits including plant primary and secondary metabolites. One well-established approach to investigating the variation in plant metabolites involves studying plant populations along elevation and latitude gradients. We considered how two space-for-time climate change gradients (elevation and latitude) influence carbohydrate reserves (soluble sugars, starches) and secondary metabolites (monoterpenes, diterpene resin acids) of lodgepole pine trees in western Canada. We were particularly interested in the relationship of terpenes and carbohydrates with a wide range of tree, site, and climatic factors. We found that only elevation had a strong influence on the expression of both terpenes and carbohydrates of trees. Specifically, as elevation increased, concentrations of monoterpenes and diterpenes generally increased and soluble sugars (glucose, sucrose, total sugars) decreased. In contrast, latitude had no impact on either of terpenes or carbohydrates. Furthermore, we found a positive relationship between concentrations of starch and total terpenes and diterpenes in the elevation study; whereas neither starches nor sugars were correlated to terpenes in the latitude study. Similarly, both terpenes and carbohydrates had a much greater number of significant correlations to site characteristics such as slope, basal area index, and sand basal area, in the elevational than in the latitude study. Overall, these results support the conclusion that both biotic and abiotic factors likely drive the patterns of primary and secondary metabolite profiles of lodgepole pine along geographical gradients. Also, presence of a positive relationship between terpenes and starches suggests an interaction between primary ad secondary metabolites of lodgepole pine trees.

Subtribe Hyptidinae (Lamiaceae): A promising source of bioactive metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

The subtribe Hyptidinae contains approximately 400 accepted species distributed in 19 genera (Hyptis, Eriope, Condea, Cantinoa, Mesosphaerum, Cyanocephalus, Hypenia, Hyptidendron, Oocephalus, Medusantha, Gymneia, Marsypianthes, Leptohyptis, Martianthus, Asterohyptis, Eplingiella, Physominthe, Eriopidion and Rhaphiodon). This is the Lamiaceae clade with the largest number of species in Brazil and high rates of endemism. Some species have been used in different parts of the world mainly as insecticides/pest repellents, wound healing and pain-relief agents, as well as for the treatment of respiratory and gastrointestinal disorders.

AIM OF THE REVIEW

This review aims to discuss the current status concerning the taxonomy, ethnobotanical uses, phytochemistry and biological properties of species which compose the subtribe Hyptidinae.

MATERIALS AND METHODS

The available information was collected from scientific databases (ScienceDirect, Pubmed, Web of Science, Scopus, Google Scholar, ChemSpider, SciFinder ACS Publications, Wiley Online Library), as well as other literature sources (e.g. books, theses).

RESULTS

The phytochemical investigations of plants of this subtribe have led to the identification of almost 300 chemical constituents of different classes such as diterpenes, triterpenes, lignans, α-pyrones, flavonoids, phenolic acids and monoterpenes and sesquiterpenes, as components of essential oils. Extracts, essential oils and isolated compounds showed a series of biological activities such as insecticide/repellent, antimicrobial and antinociceptive, justifying some of the popular uses of the plants. In addition, a very relevant fact is that several species produce podophyllotoxin and related lignans.

CONCLUSION

Several species of Hyptidinae are used in folk medicine for treating many diseases but only a small fraction of the species has been explored and most of the traditional uses have not been validated by current investigations. In addition, the species of the subtribe appear to be very promising as alternative sources of podophyllotoxin-like lignans which are the lead compounds for the semi-synthesis of teniposide and etoposide, important antineoplastic agents. Thus, there is a wide-open door for future studies, both to support the popular uses of the plants and to find new biologically active compounds in this large number of species not yet explored.

The allylic oxidation of tigliane esters

As part of a study on the structure-activity relationships of the anticancer agent tigilanol tiglate (EBC-46, 2), the allylic oxidation of phorbol triacetate (1c) and of the acetonide of its 3αH-dihydroderivative (5) was investigated. The aim was to introduce an oxygen function at C-5 en route to point-like analogues of 2, but functionalization of C-10 was instead observed. This was followed by oxidative fragmentation of ring B to the 9,10-secotigliane derivative 6 and oxidation of the endocyclic Δ⁶ double bond to the C-6/C-10 oxygen bridged 7-oxotigliane 7. Despite the over-functionalization of ring B, these observations suggest the possibility to modify positions overlooked in the oxidase phase of tigliane biosynthesis and explore novel areas of the phorbol chemical space.

Royleanone Derivatives From Plectranthus spp. as a Novel Class of P-Glycoprotein Inhibitors

Cancer is among the leading causes of death worldwide. One of the most challenging obstacles in cancer treatment is multidrug resistance (MDR). Overexpression of P-glycoprotein (P-gp) is associated with MDR. The growing incidence of cancer and the development of MDR drive the search for novel and more effective anticancer drugs to overcome the MDR problem. Royleanones are natural bioactive compounds frequently found in Plectranthus spp. The cytotoxic diterpene 6,7-dehydroroyleanone (1) is the main component of the P. madagascariensis (Pers.) Benth. essential oil, while 7α-acetoxy-6β-hydroxyroyleanone (2) can be isolated from acetonic extracts of P. grandidentatus Gürke. The reactivity of the natural royleanones 1 and 2 was explored to obtain a small library of new P-gp inhibitors. Four new derivatives (6,7-dehydro-12-O-tert-butyl-carbonate-royleanone (20), 6,7-dehydro-12-O-methylroyleanone (21), 6,7-dehydro-12-O-benzoylroyleanone (22), and 7α-acetoxy-6β-hydroxy-12-O-benzoylroyleanone (23) were obtained as pure with overall modest to excellent yields (21–97%). P-gp inhibition potential of the derivatives 20–23 was evaluated in human non-small cell lung carcinoma NCI-H460 and its MDR counterpart NCI-H460/R with the P-gp overexpression, through MTT assay. Previously prepared diterpene 7α-acetoxy-6β-benzoyloxy-12-O-(4-chloro)benzoylroyleanone (4), has also been tested. The P-gp inhibiting effects of compounds 1–4 were also assessed through a Rhodamine 123 accumulation assay. Derivatives 4 and 23 have significant P-gp inhibitory potential. Regarding stability and P-gp inhibition potential, results suggest that the formation of benzoyl esters is a more convenient approach for future derivatives with enhanced effect on the cell viability decrease. Compound 4 presented higher anti-P-gp potential than the natural diterpenes 1, 2, and 3, with comparable inhibitory potential to Dexverapamil. Moreover, derivative 4 showed the ability to sensitize the resistant NCI-H460/R cells to doxorubicin.

Structure-activity relationship, molecular docking, and molecular dynamic studies of diterpenes from marine natural products with anti-HIV activity

HIV-1 infection is a global epidemic whose treatment is limited majorly by viral resistance and adverse effects. Natural products from algae have been studied for many years, including antiviral, being an alternative to anti-HIV drug design. Since the isolation of natural products can be a hurdle, molecular modeling is an important tool to study these compounds. Herein, structure-activity relationship, molecular docking, and molecular dynamic studies were performed to direct the studies of ten marine natural products with anti-HIV activity. In the structure-activity relationship, descriptors were identified associating the anti-HIV activity of five diterpenes with possible action on the reverse transcriptase allosteric site. These diterpenes were evaluated by molecular docking, and it was identified that only dolabelladienetriol interacted in the allosteric site. Molecular dynamics suggested that the dolabelladienetriol might interfere with the viral RNA binding to HIV-1 RT by inducing a conformational change of the enzyme. Also, in silico ADMET simulations predicts that the dolabelladienetriol present a high potential to be successfully developed as a drug. Thus, applying in silico approaches was possible to suggest potential anti-HIV compounds derived from marine natural products.Communicated by Ramaswamy H. Sarma.

Ligand and Structure-based Virtual Screening of Lamiaceae Diterpenes with Potential Activity against a Novel Coronavirus (2019-nCoV)

BACKGROUND

The emergence of a new coronavirus (CoV), named 2019-nCoV, as an outbreak originated in the city of Wuhan, China, has resulted in the death of more than 3,400 people this year alone and has caused worldwide an alarming situation, particularly following previous CoV epidemics, including the Severe Acute Respiratory Syndrome (SARS) in 2003 and the Middle East Respiratory Syndrome (MERS) in 2012. Currently, no exists for infections caused by CoVs; however, some natural products may represent potential treatment resources, such as those that contain diterpenes.

OBJECTIVE

This study aimed to use computational methods to perform a virtual screening (VS) of candidate diterpenes with the potential to act as CoV inhibitors.

METHODS

1,955 diterpenes, derived from the Nepetoideae subfamily (Lamiaceae), were selected using the SistematX tool (https://sistematx.ufpb.br), which were used to make predictions. From the ChEMBL database, 3 sets of chemical structures were selected for the construction of predictive models.

RESULTS

The chemical structures of molecules with known activity against SARS CoV, two of which were tested for activity against specific viral proteins and one of which was tested for activity against the virus itself, were classified according to their pIC50 values [-log IC50 (mol/l)].

CONCLUSION

In the consensus analysis approach, combining both ligand- and structure-based VSs, 19 compounds were selected as potential CoV inhibitors, including isotanshinone IIA (01), tanshinlactone (02), isocryptotanshinone (03), and tanshinketolactone (04), which did not present toxicity within the evaluated parameters.

Isolation, reactivity, pharmacological activities and total synthesis of hispanolone and structurally related diterpenes from Labiatae plants

Hispanolone is a furolabdane diterpene isolated from Ballota hispanica, whose natural product chemistry has been summarized and updated here, including several aspects associated with the isolation, structure determination, hemisynthesis, total synthesis, and pharmacology, and related hispanolone diterpenoids that have attracted the interest of different laboratories from diverse perspective and expertise in the last forty-two years.

Alkane-, alkene-, alkyne-γ-lactones and ryanodane diterpenes from aeroponically grown Persea indica roots

This work presents the study of the roots of the Macaronesian paleoendemism Persea indica (L.) Spreng. The root biomass of this protected tree species has been produced by soil-less aeroponic culture under controlled environment. This system has important advantages over traditional plant production techniques because it provides opportunities to optimize the yield of metabolite production under well-controlled conditions, thereby facilitating commercial-scale production of bioactive compounds. Thus, for the first time a study of this type has permitted the isolation from the roots of seven undescribed dextrorotatory lactones: the alkane-γ-lactones (+)-majoranolide and (+)-dihydromajorenolide, the alkene-γ-lactones (+)-majorenolide and (+)-majorenolide acetate, and the alkyne-γ-lactones, (+)-majorynolide, (+)-majorynolide acetate and (+)-isomajorynolide. In addition, thirteen known compounds were also isolated including two possible avocadofurane precursors, avocadynone acetate and avocadenone acetate, the monoterpene esters cis- and trans-p-coumarate of (-)-borneol, and the ryanoid diterpenes cinnzeylanone, anhidrocinnzeylanine, cinnzeylanine, cinnzeylanol, epiryanodol, perseanol, cinncassiol E, perseaindicol and secoperseanol. The configuration at C-14 de two ryanodane diterpenes has also been revised in this work. Furthermore, (-)-borneol cis-p-coumarate has showed to be insecticidal to S. littoralis and cytotoxic to insect (Sf9) cells, (+)-majorenolide antifeedant to aphids and cytotoxic to Sf9, cinnceylanol antifeedant and insecticidal to S. littoralis, and (+)-majorynolide (2), insecticidal against S. littoralis, cytotoxic to Sf9 and nematicidal, suggesting a defensive role for these compounds.

Metabolic variation in Cistus monspeliensis L. ecotypes correlated to their plant-fungal interactions

The effect of environmental factors on the chemical composition of plants eventually resulting in plant growth regulation is an age-old issue in plant biology. Nowadays, the acceleration in changes in environmental conditions (e.g. global warming) can act as an incentive to investigate their correlation with metabolic changes. In this study, Cistus monspeliensis plants grown on the island of Sardinia (Italy) were used to explore the geographical-mediated metabolic variation and its repercussion on plant-fungus interactions. Samples of different ecotypes of C. monspeliensis were collected and chemically profiled by ¹H NMR and HPTLC-based metabolomics and the relationship between the variations of biological activity was examined by multivariate data analysis. The ecotypes, collected from different geographical zones and altitudes, exhibited clearly distinguishable chemical profiles, particularly in their terpene and phenolic contents. In particular, multivariate data analysis revealed several diterpenes of the labdane and clerodane series among the terpenes and methoxyflavonoids to be responsible for the differentiation. The antifungal activity of the plants was used to explore the correlation between chemical variation and biological activity. Results showed that there was a strong correlation between the metabolic profiles and the antifungal activity, revealing terpenes and methoxylated flavonoids as the main involved metabolites. This demonstrated that environmental factors can influence the chemical variation of plant ecotypes, resulting in the generation of chemotypes that are potentially adapted to their niche conditions including the plant-fungal interactions.

The Potential of Natural Diterpenes Against Tuberculosis: An Updated Review

Every year, 10 million people are affected by tuberculosis (TB). Despite being a preventable and curable disease, 1.5 million people die from TB each year, making it the world's top infectious disease. Many of the frontline antibiotics cause painful and disagreeable side effects. To mitigate the side effects from the use of chemically synthesized or clinical anti-tubercular drugs, there are many research studies focussed on natural products as a source of potential anti-tuberculosis drugs. Among different phytoconstituents, several classes of diterpenoids exert significant antimicrobial effects. This review explores diterpenoids as potential anti-tubercular drugs from natural sources. A total of 204 diterpenoids isolated from medicinal plants and marine species are discussed that inhibit the growth of Mycobacterium tuberculosis. The literature from 1994-2018 is reviewed, and 158 diterpenoids from medicinal plants, as well as 40 diterpenoids from marines, are alluded to have antituberculosis properties. The antitubercular activities discussed in the review indicate that the type of diterpenoids, the Mtb strains, substituents attached to diterpenoids and their position in the diterpenoids general skeleton can change the compounds antimycobacterial inhibitory effects.

Investigation of the potential anticancer effects of napelline and talatisamine dirterpenes on experimental brain tumor models

Brain cancers are one of the most aggressive tumours in humans. Especially, gliomas are among the deadliest of human cancers and show high resistance to chemotherapeutic agents. On the other hand, discovery of biologically effective non-synthetic biomaterials in treatments of different diseases, especially cancer, has continued to be one of the most popular research topics today. Therefore, we aimed to investigate biochemical, cytological and molecular genetic effects of napelline and talatisamine diterpenes in human U-87 MG glioma cells by using total antioxidant status and total oxidative status, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxphenyl)-2-(4-sulfophenyl)-2H-tetrozolium, inner salt and lactate dehydrogenase release assay and RT2 Prolifer PCR Arrays. Our results revealed that napelline and talatisamine exhibited cytotoxic effects at high doses. Napelline and talatisamine diterpenes increased apoptosis compared to control in U-87 MG cells. While napelline induced up-regulation of 50 and down-regulation of 13 genes, talatisamine induced up-regulation of 32 and down-regulation of 18 genes in U-87 MG cells. Napelline was shown to have a higher anticancer activity than talatisamine. We think that, napelline and talatisamine might be evaluated as potential chemotherapeutic agents for treatment of glioblastoma.

Cytotoxic and anti-inflammatory effects of lignans and diterpenes from Cupressus macrocarpa

Cupressus macrocarpa is a windbreak tree and is reported to have various cytotoxic effects. A natural product study on the leaves of C. macrocarpa has yielded ten secondary metabolites, including three new diterpenoids (1-3), four known diterpenoids (4-7), and three known lignans (8-10). The structures of all isolated compounds were elucidated via the interpretation of spectroscopic methods, especially 2D NMR and mass analyses. In the cytotoxic assays, compounds 1-3 and 7-10 showed inhibition effect against HepG2, MDA-MB-231, and A549 cells with IC₅₀ values ranging from 0.004 to 19.9 μg/mL. Moreover, the anti-inflammatory assays revealed that (-)-matairesinol (8) had significant inhibitory activities on superoxide anion generation (IC₅₀ = 2.7 ± 0.3 μM) and elastase release (IC₅₀ = 6.6 ± 0.7 μM).

Acute and subacute (28 days) toxicity of green coffee oil enriched with diterpenes cafestol and kahweol in rats

Green coffee oil enriched with cafestol and kahweol was obtained by supercritical fluid extraction using carbon dioxide while its safety and possible effects from acute and subacute treatment were evaluated in rats. For acute toxicity study, single dose of green coffee oil (2000 mg/kg) was administered by gavage in female rats. For subacute study (28 days), 32 male rats received different doses of green coffee oil extract (25, 50, and 75 mg/kg/day). In the acute toxicity study, main findings of this treatment indicated no mortality, body weight decrease, no changes in hematological and biochemical parameters, and relative weight increase in heart and thymus, without histopathological alterations in all assessed organs. All these findings suggest that LD₅₀ is higher than aforesaid dose. In the subacute toxicity, main findings showed body weight decrease mainly at the highest dose without food consumption change, serum glucose and tryglicerides levels decrease, and relative weight increase in liver. As evidenced in histopathological pictures, no changes were observed at all treated doses. Our study suggest that green coffee oil can be explored to clinically develop new hypocholesteromic and hypoglycemic agents. However, further studies evaluating long-term effects are needed in order to have sufficient safety evidence for its use in humans.

The novel diterpene 7β-acetoxy-20-hydroxy-19,20-epoxyroyleanone from Salvia corrugata shows complex cytotoxic activities against human breast epithelial cells

AIMS

The aim of this study was the characterization of the in vitro cytotoxic properties of a recently isolated diterpene compound, 7β-acetoxy-20-hydroxy-19,20-epoxyroyleanone (compound 1), extracted from Salvia corrugata, versus human cell lines.

MAIN METHODS

We used as model study immortalized breast epithelial cells MCF10A and two ERBB2⁺ breast cancer (BCa) cell lines, SKBR-3 and BT474. Compound 1 was isolated by methanolic extraction from regenerated shoots of Salvia corrugata Vahl, and purified by high pressure liquid chromatography (HPLC). Flow cytometry (FCM) was employed for cell cycle, apoptosis and reactive oxygen species (ROS) analysis. Cell morphology was assessed by immunofluorescence and transmission electron microscopy (TEM).

KEY FINDINGS

Compound 1 inhibited cell survival of all breast cell lines. In particular, compound 1 promoted cell cycle arrest in the G0/G1 phase and apoptosis along with impairment of the mitochondrial function, which was reflected in a gross alteration of the mitochondrial network structure. Furthermore, we also detected a potent activation of the ERK1/2 kinase, which suggested the induction of reactive oxygen species (ROS). Partial rescue of survival obtained with n-acetylcysteine (NAC) when coadminstered with compound 1 further supported a contribution of ROS mediated mechanisms to the growth-arrest and proapoptotic activity of compound 1 in both BCa cell lines. ROS production was indeed confirmed in SKBR-3.

SIGNIFICANCE

Our findings show that compound 1 has a cytotoxic activity against both human normal and cancer cell lines derived from breast epithelia, which is mediated by ROS generation and mitochondrial damage.

Characterization and hepatoprotective evaluation of sesquiterpenes and diterpenes from the aerial parts of Juniperus sabina L

Previously, we reported on the hepatoprotective activity of the total extract of Juniperus sabina L. against CCl₄ induced liver toxicity in experimental animals. Biologically directed phytochemical study was conducted to identify the active compounds. Male Wistar rats and the standard drug silymarin were used in the study. Hepatoprotective activity was evaluated via serum biochemical parameters such as aspartate amino transferase (AST), alanine aminotransferase (ALT), gamma glutamyl transpeptidase (GGT), alkaline phosphatase (ALP) and total bilirubin. Tissue parameters including non-protein sulfhydryl groups (NP-SH), malonaldehyde (MDA) and total protein (TP) were also determined. Histopathological study was conducted utilizing Mayer's hematoxylin stain, Periodic Acid Schiff - Hematoxylin (PAS-H) and Masson trichrome technique on light microscope. Electron microscope images were also generated for the study. The activity of the total extract was trapped to the petroleum ether fraction after liquid-liquid fractionation where 51% reduction in the levels of AST, bilirubin and 44% in the levels of ALT were observed. Chromatographic purification of the petroleum ether fraction resulted in the isolation of nine compounds namely: trans-calamenene (1), cadalene (cadalin) (2), epi-cubenol (3), manool (4), calamenene-10β-ol (5), calamenene-10α-ol (6), 4-epi-abietic acid (7), sandaracopimaric acid (8) and isopimaric acid (9). Compounds 1-3, 5 and 6 are belonging to cadinane sesquiterepenes, while compounds 4, 7-9 were of diterpene skeleton. The major compounds were tested for their hepatoprotective effect. Compounds 3 showed marked improvement in the levels of AST and ALT, compound 4 was effective in improving the levels of AST, ALT, GGT, ALP and bilirubin, while compound 7 showed significant improvement in GGT, ALP and bilirubin levels.

Distribution of the anti-inflammatory and anti-depressant compounds: Incensole and incensole acetate in genus Boswellia

Incensole and its acetate have shown anti-inflammatory and anti-depression activities due to their ability to activate ion channels in the brain to alleviate anxiety or depression. The natural occurrence of these two structurally and medicinally fascinating 14-membered diterpenoids was reported mainly from the genus Boswellia. Incensole and incensole acetate were detected in and isolated from both essential oils and resins of frankincense. One total synthesis was reported for incensole. Both incensole and its acetate served as precursors for several synthetic transformations. Given the fact that no specific enzymes were isolated from Boswellia trees, the major sources for incensole and incensole acetate, the biosynthetic pathway of these two compounds was only speculated. Recent studies on incensole and incensole acetate including ours have revealed another secret of the ancient drug. Understanding their mode of action will open a door in modern neurobiology and provides new insights on the mysterious diseases of the nervous system. This review interpretatively discusses the natural existence of incensole and incensole acetate, the variation of their percentages in different Boswellia species and other sources, their synthetic modifications, their biosynthesis and their therapeutic potential.

Correlation between the composition of green Arabica coffee beans and the sensory quality of coffee brews

This research aimed to correlate the composition of green Arabica coffee beans with the sensory quality coffee brews. The chemical composition of green Arabica coffee bean (66 samples) from three coffee quality contests was analyzed by near-infrared spectroscopy. Coffee brews with lower quality scores were correlated with high levels of caffeine, protein, chlorogenic acids and total titratable acidity (TTA) in the green coffee beans. High sucrose/TTA and cafestol/kahweol ratios in the green coffee beans were usually associated with higher scores for the coffee brews. By multivariate analysis techniques, the samples were separated into groups according to production years indicating a strong influence of the environmental conditions on the chemical composition. The profile of the composition of the crude coffee can be indicative of the sensory quality of the coffee brews, relevant information for producers and industry since the green beans are the material used for trading and purchasing coffee.

In vitro and in vivo anti-Helicobacter pylori activity of Casearia sylvestris leaf derivatives

ETHNOPHARMACOLOGICAL RELEVANCE

The number of bacterial strains that are resistant to multiple conventional antimicrobial agents is increasing. In this context, natural products have been widely used as a strategy to treat diseases caused by bacteria. Infections by Helicobacter pylori have attracted attention because they are directly related to severe gastric medical conditions. Casearia sylvestris Swartz, popularly known as guaçatonga, is largely employed to treat gastric disorders in Brazilian folk medicine. This plant species has aroused much interest mainly because it displays anti-inflammatory activity and can act as an antiulcer agent.

AIM OF THE STUDY

To evaluate the in vitro and in vivo anti-H. pylori action of C. sylvestris leaf derivatives incorporated or not in a nanostructured drug delivery system.

MATERIALS AND METHODS

The essential oil (obtained by hydrodistillation) and ethanolic extract (obtained by maceration) were obtained from C. sylvestris leaves. The ethanolic extract was submitted to fractionation through solid phase extraction and column chromatography, to yield the ethanolic fractions. Hydrolyzed casearin J was achieved by submitting isolated casearin J to acid hydrolysis. The derivatives were chemically characterized by nuclear magnetic resonance (NMR), gas chromatography (GC), and gas chromatography-mass spectrometry (GC-MS) analyses. A nanostructured lipid system was used as drug delivery system. To assess the in vitro antibacterial activity of C. sylvestris leaf essential oil, ethanolic extract, and derivatives, microdilution, biofilm, and time-kill assays were performed against H. pylori ATCC 43504. Finally, the in vivo action was investigated by employing male Wistar rats experimentally infected with H. pylori.

RESULTS

Many C. sylvestris leaf derivatives presented significant in vitro activity against H. pylori. Among the derivatives, fraction 2 (F2) was the most effective. In vivo tests showed that both the ethanolic extract and F2 decreased the ulcerative lesion size, but only the ethanolic extract eradicated H. pylori from the gastric lesions. Incorporation of plant derivatives in nanostructured lipid system blunted the in vitro action, as demonstrated by the microdilution assay. However, this incorporation improved the ethanolic extract activity against biofilms.

CONCLUSION

C. sylvestris leaf derivatives are effective against H. pylori both in vitro and in vivo. According to phytochemical analyses, these derivatives are rich in terpenoids, which could be related to the anti-H. pylori action. Synergism could also underlie C. sylvestris efficacy judging from the fact that the sub-fractions and isolated compounds had lower activity than the extract. Incorporation in a nanostructured lipid system did not improve the activity of the compounds in our in vivo protocol.

A syn-ent-labdadiene derivative with a rare spiro-β-lactone function from the male cones of Wollemia nobilis

An undescribed labdane-like diterpene with a rare spiro-β-lactone function was identified from the ethanol extract of the male cones of the coniferous tree Wollemia nobilis. This spirolabdadienolide (IUPAC name: syn-ent-8(17),13-labdadien-19,18-olid-15-oic acid methyl ester; trivial name: wollemolide), was isolated by means of traditional and high performance chromatography techniques and structurally elucidated through NMR and MS. In addition, six further known metabolites were evidenced in the extract. Wollemolide, which may be considered an additional chemotaxonomic marker, and 4'-O-methyl-scutellarein, a simple flavonoid, had not been isolated in our previous phytochemical study on the same plant organ. This demonstrates how the molecular pattern of a plant species is in continuous movement and changes with the passing of time according to the climate of the year.

Chemistry of the Secondary Metabolites of Termites

Isolation, structure determination, synthesis, and biochemistry of the low-molecular-weight compounds of the secretion of exocrine glands of termites are described, with an emphasis on pheromones and defensive compounds.

Engineering of CYP76AH15 can improve activity and specificity towards forskolin biosynthesis in yeast

Background

Forskolin is a high-value diterpenoid produced exclusively by the Lamiaceae plant Coleus forskohlii. Today forskolin is used pharmaceutically for its adenyl-cyclase activating properties. The limited availability of pure  forskolin is currently hindering its full utilization, thus a new environmentally friendly, scalable and sustainable strategy is needed for forskolin production. Recently, the entire biosynthetic pathway leading to forskolin was elucidated. The key steps of the pathway are catalyzed by cytochrome P450 enzymes (CYPs), which have been shown to be the limiting steps of the pathway. Here we study whether protein engineering of the substrate recognition sites (SRSs) of CYPs can improve their efficiency towards forskolin biosynthesis in yeast.

Results

As a proof of concept, we engineered the enzyme responsible for the first putative oxygenation step of the forskolin pathway: the conversion of 13R-manoyl oxide to 11-oxo-13R-manoyl oxide, catalyzed by the CYP76AH15. Four CYP76AH15 variants—engineered in the SRS regions—yielded at least a twofold increase of 11-oxo-13R-manoyl oxide when expressed in yeast cells grown in microtiter plates. The highest titers (5.6-fold increase) were observed with the variant A99I, mutated in the SRS1 region. Double or triple CYP76AH15 mutant variants resulted in additional enzymes with optimized performances. Moreover, in planta CYP76AH15 can synthesize ferruginol from miltiradiene. In this work, we showed that the mutants affecting 11-oxo-13R-manoyl oxide synthesis, do not affect ferruginol production, and vice versa.

The best performing variant, A99I, was utilized to reconstruct the forskolin biosynthetic pathway in yeast cells. Although these strains showed increased 11-oxo-manoyl oxide production and higher accumulation of other pathway intermediates compared to the native CYP76AH15, lower production of forskolin was observed.

Conclusions

As demonstrated for CYP76AH15, site-directed mutagenesis of SRS regions of plant CYPs may be an efficient and targeted approach to increase the performance of these enzymes. Although in this work we have managed to achieve higher efficiency and specificity of the first CYP of the pathway, further work is necessary in order to increase the overall production of forskolin in yeast cells.

Electronic supplementary material

The online version of this article (10.1186/s12934-018-1027-3) contains supplementary material, which is available to authorized users.

Effect of Diterpenes on Hepatic System

Complication in the hepatic system is a major concern for human being. To control and keep the hepatic system healthy, a number of measures, including drug treatments are considered. Diterpenes are essential oils having promising antioxidant and cytotoxic properties along with their genotoxic and mutagenic effects. These agents are good targets for health promotion, especially in the light of their potential organo-protectivity. We searched in the databases, PUBMED and SCIENCE DIRECT from June 2011 to June 2016 for publishing evidence on diterpenes and their effects on hepatic system. After sorting the data, activity-wise findings are discussed in this current article. The results suggest that diterpenes have hepatoprotectivity property via antioxidant and anti-inflammatory, antimicrobial, anticancer/antitumor, hypolipidemic, anti-apoptosis, autophagic, antimetastasize, anti-proliferating, anti-fibrosis as well as receptor and serum biomarkers mediated pathways. On the other hand, hepatoxic effects of diterpenes are also accounted with cytotoxicity, apoptotic cell death and downregulation of cytochrome P450 systems. A number of important diterpenes have been reported in the literatures that act on the hepatic system. Some of them exert toxic effects on the liver, especially in rodent model. Hence, more extensive researches are recommended that will highlight their mechanism of action on the liver.

A screening method for cardiovascular active compounds in marine algae

The interaction of bioactive compounds from ethanolic extracts of selected marine algae samples, separated on chromatographic plates, with nitric/nitrous acid was investigated. The nature of bioactive compounds in the marine algae extracts was characterised using UV absorption spectra before and after reaction with diluted nitric acid, and from the characteristic colour reaction after derivatization with anisaldehyde. It was found that diterpenes from Dictyota dichotoma, an edible brown algae, and sterols from green algae Caulerpa brachypus, bind nitric oxide and may act as a nitric oxide carrier. Although the carotenoid fucoxanthin, found in all brown marine algae also binds nitric oxide, the bonds between nitrogen and the fucoxanthin molecule are much stronger. Further studies are required to evaluate the effects of diterpenes from Dictyota dichotoma and sterols from green algae Caulerpa brachypus to see if they have beneficial cardiovascular effects. The method reported here should prove useful in screening large numbers of algae species for compounds with cardiovascular activity.

Anti-inflammatory and anti-angiogenic activities in vitro of eight diterpenes from Daphne genkwa based on hierarchical cluster and principal component analysis

Rheumatoid arthritis (RA) is one of the most prevalent chronic inflammatory and angiogenic diseases. The aim of this study was to evaluate the anti-inflammatory and anti-angiogenic activities in vitro of eight diterpenoids isolated from Daphne genkwa. LC-MS was used to identify diterpenes isolated from D. genkwa. The anti-inflammatory and anti-angiogenic activities of eight diterpenoids were evaluated on LPS-induced macrophage RAW264.7 cells and TNF-α-stimulated human umbilical vein endothelial cells (HUVECs) using hierarchical cluster analysis (HCA) and principal component analysis (PCA). The eight diterpenes isolated from D. genkwa were identified as yuanhuaphnin, isoyuanhuacine, 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl, yuanhuagine, isoyuanhuadine, yuanhuadine, yuanhuaoate C and yuanhuacine. All the eight diterpenes significantly down-regulated the excessive secretion of TNF-α, IL-6, IL-1β and NO in LPS-induced RAW264.7 macrophages. However, only 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl markedly reduced production of VEGF, MMP-3, ICAM and VCAM in TNF-α-stimulated HUVECs. HCA obtained 4 clusters, containing 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl, isoyuanhuacine, isoyuanhuadine and five other compounds. PCA showed that the ranking of diterpenes sorted by efficacy from highest to lowest was 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl, yuanhuaphnin, isoyuanhuacine, yuanhuacine, yuanhuaoate C, yuanhuagine, isoyuanhuadine, yuanhuadine. In conclusion, eight diterpenes isolated from D. genkwa showed different levels of activity in LPS-induced RAW264.7 cells and TNF-α-stimulated HUVECs. The comprehensive evaluation of activity by HCA and PCA indicated that of the eight diterpenes, 12-O-(2'E,4'E-decadienoyl)-4-hydroxyphorbol-13-acetyl was the best, and can be developed as a new drug for RA therapy.

Physical characteristics of the paper filter and low cafestol content filter coffee brews

The results found in the literature concerning the effect of consuming filter coffee brews on increasing the blood cholesterol levels due to the presence of diterpenes, are divergent. Thus the present research evaluated the diterpene (cafestol and kahweol) concentrations in filter coffee brews prepared with paper filters of different sizes, colors and origins (Brazil, Japan, The United States of America, Germany, France and the Netherlands), with and without micro perforations. This is the first study that reports the physical characteristics of paper filter and its importance to obtain filter coffee brew with low cafestol content. Thus, a sample of Catuai cultivar coffee with high cafestol content was roasted to a medium-light degree and used to prepare the brews in a 1:10 ratio (coffee powder to water). The diterpenes were extracted by direct saponification and quantified and identified by HPLC-DAD-MS/MS. The paper filters were physically characterized by measuring their grammage, and the fat permeation rate calculated in order to better understand the differences between the filters which allow one to obtain higher or lower diterpene contents. The cafestol and kahweol concentrations in the brews varied from 1.62 to 2.98 mg/L and from 0.73 to 1.96 mg/L, respectively. The highest cafestol and kahweol concentrations were obtained using paper filters with micro perforations, considering similar sized paper filters. The paper filters showed high fat permeability and grammages between 50.46 and 67.48 g/m². The diterpene retention capacities of the filters produced in the different countries were similar. The results showed that the porosity of the paper filter and the particle size of the ground roasted coffee were determinant factors in obtaining filter coffee brews with lower cafestol contents.