Diterpenes from Salvia broussonetii transformed roots and their insecticidal activity

Elucidation of the biosynthesis of carnosic acid and its reconstitution in yeast

Rosemary extracts containing the phenolic diterpenes carnosic acid and its derivative carnosol are approved food additives used in an increasingly wide range of products to enhance shelf-life, thanks to their high anti-oxidant activity. We describe here the elucidation of the complete biosynthetic pathway of carnosic acid and its reconstitution in yeast cells. Cytochrome P450 oxygenases (CYP76AH22-24) from Rosmarinus officinalis and Salvia fruticosa already characterized as ferruginol synthases are also able to produce 11-hydroxyferruginol. Modelling-based mutagenesis of three amino acids in the related ferruginol synthase (CYP76AH1) from S. miltiorrhiza is sufficient to convert it to a 11-hydroxyferruginol synthase (HFS). The three sequential C20 oxidations for the conversion of 11-hydroxyferruginol to carnosic acid are catalysed by the related CYP76AK6-8. The availability of the genes for the biosynthesis of carnosic acid opens opportunities for the metabolic engineering of phenolic diterpenes, a class of compounds with potent anti-oxidant, anti-inflammatory and anti-tumour activities.

Diterpenes are plant products with high antioxidant properties and potential application as food additives and therapeutics. Here, the authors describe the complete biosynthetic pathway of carnosic acid and reconstruct it in yeast, opening the way to metabolic engineering of phenolic diterpenes.

Dirhodium(II)-Catalyzed Annulation of Enoldiazoacetamides with α-Diazoketones: An Efficient and Highly Selective Approach to Fused and Bridged Ring Systems

A dirhodium(II)-catalyzed annulation reaction between two structurally different diazocarbonyl compounds furnishes the donor-acceptor cyclopropane-fused benzoxa[3.2.1]octane scaffold with excellent chemo-, regio-, and diastereoselectivity under exceptionally mild conditions. The composite transformation occurs by [3+2]-cycloaddition between donor-acceptor cyclopropenes generated from enoldiazoacetamides and carbonyl ylides formed from intramolecular carbene-carbonyl cyclization in one pot with one catalyst. The annulation products can be readily transformed into benzoxa[3.3.1]nonane and hexahydronaphthofuran derivatives with exact stereocontrol. This method allows the efficient construction of three fused and bridged ring systems, all of which are important skeletons of numerous biologically active natural products.

Establishment of Salvia castanea Diels f. tomentosa Stib. hairy root cultures and the promotion of tanshinone accumulation and gene expression with Ag⁺, methyl jasmonate, and yeast extract elicitation

Salvia castanea Diels f. tomentosa Stib. is an endemic medicinal plant distributed in China, and the notably high content of tanshinone IIA in the root is proven effective for the therapy of heart diseases. Hairy root induction of this Salvia species was inoculated with Agrobacterium rhizogenes strain ATCC 15834. Transformed hairy root was cultured in 6,7-V liquid medium for growth kinetics assessment and elicitation. An S curve was present in the hairy root cultures based on the fresh and dry weights with an interval of 3 days. An optimum concentration of the applied elicitors (15 μM Ag(+), 200 μM methyl jasmonate, and 200 mg l(-1) yeast extract elicitor) benefitted both the growth status and tanshinone accumulation in the hairy root cultures. Tanshinone IIA contents were mostly stimulated 1.8-fold and 1.99-fold compared with the control by Ag(+) and methyl jasmonate elicitation, respectively. Yeast extract dramatically enhanced dry mass accumulation, while it promoted cryptotanshinone content of 2.84 ± 0.33 mg g(-1) dry weight at most in the hairy root cultures. Selected elicitors diversely influenced tanshinone accumulation in the time courses of hairy root cultures within 7 days. Furthermore, transcripts of selected genes in the tanshinone biosynthetic pathway were remarkably upregulated with elicitation. Yeast extract elicitor heightened 13.9-fold of isopentenyl diphosphate isomerase expression level at 12 h, while it increased 16.7-fold of geranylgeranyl diphosphate synthase transcript at 24 h compared with that of the control, which was more effective than Ag(+) and methyl jasmonate. This study provided a convenient hairy root culture system of S. castanea Diels f. tomentosa Stib. for tanshinone production for the first time.

Substolides A-G, germacrane sesquiterpenoids from Salvia substolonifera

Chemical investigation of the whole plants of Salvia substolonifera E.Peter yielded seven germacrane sesquiterpenoids, substolides A-G (1-7), an ethoxylated artifact (8), and two known analogues, 6β-tigloyloxyglechomafuran (9) and castanin F (10). Four germacrane 8-acetylation derivatives (1a-4a) were obtained by chemical transformation. Their structures and relative or absolute configurations were elucidated by intensive spectroscopic methods, and single-crystal X-ray diffraction analysis. Compounds 1a-4a, and 5-10 were evaluated for their in vitro anti-angiogenic effects. Compounds 7 and 9 significantly inhibited VEGF-induced human umbilical vein endothelial cell (HUVEC) proliferation in vitro, with IC50 values of 16.15 ± 0.19, and 4.03 ± 0.26 μM, respectively. The structure activity relationship of these compounds is discussed.

An antibacterial ortho-quinone diterpenoid and its derivatives from Caryopteris mongolica

To identify antibacterial components in traditional Mongolian medicinal plant Caryopteris mongolica, an ortho-quinone abietane caryopteron A (1) and three its derivatives caryopteron B-D (2-4) were isolated from the roots of the plant together with three known abietanes demethylcryptojaponol (5), 6α-hydroxydemethyl cryptojaponol (6), and 14-deoxycoleon U (7). The chemical structures of these abietane derivatives were elucidated on the basis of spectroscopic data. Compounds 1-4 had C-13 methylcyclopropane substructures, and 2-4 had a hexanedioic anhydride ring C instead of ortho-quinone in 1. The stereochemistry of these compound was assumed from NOE spectra and ECD Cotton effects. Compounds 1 and 5-7 showed antibacterial activities against the Gram-positive bacteria Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, and Micrococcus luteus, being 1 the more potent.

Cholinesterase-inhibitory diterpenoids and chemical constituents from aerial parts of Caryopteris mongolica

A diterpenoid diglucoside (12,19-di-O-β-D-glucopyranosyl-11-hydroxyabieta-8,11,13-triene-19-one), isoscutellarein 7-O-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranoside, isoscutellarein 7-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside, hypolaetin 7-O-[6″-O-(p-E-coumaroyl)]-β-D-glucopyranoside, hypolaetin 7-O-[6″-O-(E-caffeoyl)]-β-D-glucopyranoside, and 15 known compounds were isolated from aerial parts of the Mongolian medicinal plant Caryopteris mongolica. The cholinesterase-inhibitory activities of the constituents were estimated. The abietane diterpenoids (12-O-demethylcryptojaponol and 6α-hydroxydemethylcryptojaponol) showed potent inhibitory activity against acetylcholinesterase from human erythrocytes and electric eel, and against butyrylcholinesterase from horse serum.

Using Hairy Roots for Production of Valuable Plant Secondary Metabolites

Plants synthesize a wide variety of natural products, which are traditionally termed secondary metabolites and, more recently, coined specialized metabolites. While these chemical compounds are employed by plants for interactions with their environment, humans have long since explored and exploited plant secondary metabolites for medicinal and practical uses. Due to the tissue-specific and low-abundance accumulation of these metabolites, alternative means of production in systems other than intact plants are sought after. To this end, hairy root culture presents an excellent platform for producing valuable secondary metabolites. This chapter will focus on several major groups of secondary metabolites that are manufactured by hairy roots established from different plant species. Additionally, the methods for preservations of hairy roots will also be reviewed.

Anti-apoptotic effect of taxodione on serum/glucose deprivation-induced PC12 cells death

Taxodione, a diterpenoid from the roots of Salvia chorassanica Bunge, possesses cytotoxic, apoptotic, and antimicrobial activity. This study was designed to investigate the protective effects of taxodione on serum/glucose deprivation-induced ischemic injury in PC12 cells and related mechanisms. In an in vitro model of ischemia, PC12 cells were exposed to serum and glucose deprivation for 6 and 18 h. The protective effects of the methanol extract of S. chorassanica and taxodione were assessed using alamarBlue(®) assay. Intracellular ROS production was measured by fluorimetry using 2',7'-dichlorofluorescin diacetate (DCFH-DA). The levels of PARP, Bcl-2, and Bax proteins were detected after western blot analysis. It was shown that taxodione (0.2-1.5 μM) significantly increased cell viability in a dose-dependent manner after ischemic insult. Taxodione has antioxidant activity and protects PC12 cells against oxidative stress-induced apoptotic cell death. Meanwhile, pretreatment with taxodione significantly induced an increase in Bcl-2 and a decrease in Bax protein level. The results of this study confirmed the protective effect of taxodione in serum/glucose deprivation-induced ischemic injury and the putative role of apoptosis as a underling mechanisms. Thus, it would be fair to consider taxodione as a promising ingredient of S. chorassanica for the expansion on novel class of anti-ischemic agents.

Cytotoxic diterpenoids from Salvia yunnanensis

Forty-six abietane type diterpenoids possessing nine different fused ring systems were characterized from the roots of Salvia yunnanensis, six of which (salyunnanins A-F, 1-6) had different nor-abietane, homo-abietane, seco-abietane, and normal abietane architectures. Their structures were elucidated by comprehensive NMR and MS spectroscopic analyses. The inhibitory activities of these isolates against six human tumor lines were tested in vitro. Several of the compounds exhibited substantial cytotoxicity with IC50 values of 0.86-10.1μM.

Diterpenoids from the Chinese liverwort Heteroscyphus tener and their antiproliferative effects

Four new ent-labdane diterpenoids, heteroscyphins A-D (1-4), and four known diterpenoids (5-8) were isolated from the Chinese liverwort Heteroscyphus tener (Steph.) Schiffn. The absolute configuration of compound 1 was defined by single-crystal X-ray diffraction using Cu Kα radiation. Cytotoxicity tests revealed that compounds 3 and 5 exhibited modest activity against seven cancer cell lines. Compound 5 showed inhibitory effects on prostate cancer (PCa) cell proliferation but with less inhibition on non-neoplastic prostate epithelial cells. Compound 5 markedly caused cell growth arrest at the G0/G1 phase and induced cellular apoptosis through ROS-mediated DNA damage in PCa cells.

Cancer chemopreventive diterpenes from Salvia corrugata

NMR and NP-HPLC-UV profiling of the exudate of Salvia corrugata revealed that its secondary metabolite composition was largely dominated by α-hydroxy-β-isopropyl-benzoquinone diterpenoids. Among them, four diterpenes not described previously were isolated and identified as fruticulin C (3), 7α-methoxy-19-acetoxy-royleanone (4), 7α,19-diacetoxy-royleanone (5), and 7-dehydroxy-conacytone (7). In addition, the known diterpenes fruticulin A (1), demethyl-fruticulin A (2) and 7α-O-methyl-conacytone (6) were also obtained. The isolated compounds were evaluated for their cancer chemopreventive activity by measuring quinone reductase induction activity and histone deacetylase inhibition. Three compounds (1, 2 and 5) showed promising activity.

Biological Activity of Bicyclic and Tricyclic Diterpenoids from Salvia Species of Immediate Pharmacological and Pharmaceutical Interest

Diterpenoids are a class of compounds that derive from the condensation of four isoprene units that leads to a wide variety of complex chemical structures, including acyclic bi-, tri-and tetra-cyclic compounds; in Salvia species, only bi-, tri-and tetra-cyclic compounds have been found. This review covers a wide range of biological activities and mode of action of diterpenoids isolated from Salvia species that might raise some pharmacological and pharmaceutical interest.

We have produced a synoptic table where the biological activities of the main active principles are summarized. Our analysis emphasizes that diterpenoids from Salvia species continue to be a plant defence system since their antimicrobic activity. Experimental studies show that most of diterpenoids considered have cytotoxic and / or antiproliferative activity. Some of them have also cardiovascular and central effects. In a less extended manner, diterpenoids from Salvia species show gastrointestinal, urinary, antinflammatory, antidiabetic, ipolipidemic and antiaggregating effects.

In the last decade, several clinical trials have been developed in order to investigate the real value of Salvia extracts treatment; results obtained are promising and confer scientific basis in the use of medicinal plants from folk medicine.

Terpenoids from Salvia trijuga

Nine new germacrane sesquiterpenes, trijugins A-I (1-9), a new lupane triterpenoid, 3alpha-O-acetyl-20(29)-lupen-2alpha-ol (10), and 24 known terpenoids were isolated from Salvia trijuga. The structure of compound 1 was confirmed by single-crystal X-ray diffraction. Compounds 1-10 and 32 were evaluated for their cytotoxicity against five human tumor cell lines. Compounds 9 and 32 exhibited moderate toxicity effects against several cell lines.

The administration of demethyl fruticulin A from Salvia corrugata to mammalian cells lines induces "anoikis", a special form of apoptosis

Recently demethyl fruticulin A was identified as the major diterpenoid component of the exudates produced by the trichomes of Salvia corrugata leafs. Given the documented apoptotic effects of some of the other known components of the exudates from Salvia species, we assessed if demethyl fruticulin A, once administered to mammalian cells, was involved in the onset of apoptosis and if its biological effects were exerted through the participation of a scavenger membrane receptor, CD36. Three model cell lines were chosen, one of which lacking CD36 expression. Functional availability of the receptor, or its transcriptional rate, were blocked/reduced with a specific antibody or by the administration of vitamin E. Immunodetection of cell cytoskeletal components and tunel analysis revealed that demethyl fruticulin A triggers the onset of anoikis, a special form of apoptosis induced by cell detachment from the substrate. Impairment of CD36 availability/transcription confirmed the receptor partial involvement in the intake of the substance and in anoikis, as also sustained by FACS analysis and by the downregulation of p95, a marker of anoikis, upon blockade of CD36 transcription. However, experiments with CD36-deficient cells suggested that alternate pathways, still to be determined, may take part in the biological effects exerted by demethyl fruticulin A.

Hairy root cultures for secondary metabolites production

Hairy roots (HRs) are differentiated cultures of transformed roots generated by the infection of wounded higher plants with Agrobacterium rhizogenes. This pathogen causes the HR disease leading to the neoplastic growth of roots that are characterized by high growth rate in hormone free media and genetic stability. HRs produce the same phytochemicals pattern of the corresponding wild type organ. High stability and productivity features allow the exploitation of HRs as valuable biotechnological tool for the production of plant secondary metabolites. In addition, several elicitation methods can be used to further enhance their accumulation in both small and large scale production. However, in the latter case, cultivation in bioreactors should be still optimized. HRs can be also utilised as biological farm for the production of recombinant proteins, hence holding additional potential for industrial use. HR technology has been strongly improved by increased knowledge of molecular mechanisms underlying their development. The present review summarizes updated aspects of the hairy root induction, genetics and metabolite production.

Redetermination and absolute configuration of 6-hydroxy-salvinolone

The crystal structure of the title compound [systematic name: 5,6,10-trihydr­oxy-7-isopropyl-1,1,4a-trimethyl-2,3,4,4a-tetra­hydro­phenanthren-9(1H)-one], C₂₀H₂₆O₄, has been reported previously [Salae et al. (2009 ▶). Acta Cryst. E65, o2379–o2380], but the absolute configuration could not be determined as there was no significant anomalous dispersion using data collected with Mo radiation. The absolute configuration has now been determined by refinement of the Flack parameter with data collected using Cu radiation. The absolute configuration at position 4a of the diterpenoid is (R)-methyl; other features of the mol­ecule and its crystal packing are similar to those previously described.

6-Hydroxy-salvinolone

The title compound {systematic name: 5,6,10-trihydr­oxy-7-iso­propyl-1,1,4a-trimethyl-2,3,4,4a-tetra­hydro­phenanthren-9(1H)-one}, C₂₀H₂₆O₄, is a diterpenoid which was isolated from the roots of Premna obtusifolia. The mol­ecule has three fused six-membered rings; the cyclo­hexane ring is in a twisted-boat conformation and the cyclo­hexene ring adopts a sofa form. Intra­molecular O—H⋯O hydrogen bonds generate two S(5) ring motifs. In the crystal, mol­ecules are linked into infinite one-dimensional chains along the [001] direction by O—H⋯O hydrogen bonds and weak C—H⋯O inter­actions.

Antioxidant diterpenoids from the roots of Salvia barrelieri

INTRODUCTION

The phytochemical and biological studies carried out on Salvia species showed that their extracts and constituents have various biological activities.

OBJECTIVE

The aim of this study was the isolation of diterpenoids from the roots of Salvia barrelieri Ettling and the determination of the antioxidant activity.

METHODOLOGY

Chromatographic methods were used for fractionation and isolation, respectively. Structure elucidation was established by spectroscopic methods. Five antioxidant assays were performed.

RESULTS

Three new abietane diterpenoids barreliol, royleanone 12-methyl ether and 7-epi-salviviridinol, and six known diterpenoids, with a known dammarane triterpenoid, pyxinol were isolated. The absolute stereochemistry of pyxinol was confirmed by X-ray analysis.

CONCLUSION

Taxodione exhibited the highest antioxidant activity among the tested compounds.

Abietane diterpenoids from the bark of Cryptomeria fortunei

Four new abietane diterpenoids, fortunins A-D (1-4), and six new 18-hydroxymethylene abietane diterpenoids, fortunins E-J (5-10), along with 12 known diterpenoids, were isolated from the bark of Cryptomeria fortunei. The structures of new compounds were established on the basis of 1D and 2D NMR and other spectroscopic analyses.

Rearranged Clerodane and Abietane Derived Diterpenoids from American Salvia Species

The genus Salvia L. (Tribe Mentheae) is the largest of the Lamiaceae with 1000 species widespread throughout the world. Phytochemical studies of several Salvia species have established an interesting chemical profile for the genus including sterols, flavonoids and triterpenoids. However, the most characteristic secondary metabolites of the genus are diterpenoids. One of the most distinguishing features of Salvia genus is the number of rearranged diterpene skeletons isolated from these plants. Until now, over 30 rearranged diterpene skeletons have been described for both Old and New World representatives of the genus. In this review, a survey of recent literature data regarding rearranged clerodane and abietane diterpenoids from American Salvia species is presented.

Reconciling Icetexane Biosynthetic Connections with Their Chemical Synthesis: Total Synthesis of (±)-5,6-Dihydro-6α-hydroxysalviasperanol, (±)-Brussonol, and (±)-Abrotanone

A unified strategy for the chemical synthesis of the icetexane diterpenoids brussonol and 5,6-dihydro-6alpha-hydroxysalviasperanol has led to a structural revision of the recently isolated natural products abrotandiol and abrotanone.

Semisynthesis of Isetexane Diterpenoid Analogues and Their Cytotoxic Activity

Isetexane diterpene analogues were semisynthesized from demethylsalvicanol isolated from Perovskia abrotanoides (Labiatae). The structure and cytotoxic activity relationships (SAR) of the natural parent diterpene, demethylsalvicanol, and its semisynthetic analogues were studied by using P388 murine leukemia cells.

Abietane diterpene alkaloids from Salvia yunnanensis

Nine new abietane diterpene alkaloids containing an oxazole ring, salviamines A-F (1-6) and isosalviamines C-E (7-9), together with 17 known abietane diterpenes, were isolated and characterized from the roots of Salvia yunnanensis. The structures of 1-9 were elucidated by interpretation of their spectroscopic data.