Benjamín Rodríguez

The antifeedant activity of clerodane diterpenoids from Teucrium

Abstract Clerodane diterpenoid compounds from Teucrium (Labiatae) were assayed for antifeedant activity against larvae of Spodoptera littoralis and Heliothis armigera . The functional groups responsible for antifeedant activity are discussed.

Abietane diterpenoids from the root of Salvia phlomoides

Abstract From the root of Salvia phlomoides three new abietane diterpenoids, demethylcryptojaponol, 14-deoxycoleon U and salviphlomone, have been isolated, besides the previously known diterpenes 8,13-abietadiene, 8,11,13-abietatriene, royleanone, 7α-acetoxyroyleanone, taxodione, taxodone, cryptojaponol and sugiol. The structures of demethylcryptojaponol (11,12-dihydroxy-8,11,13-abietatrien-7-one), 14-deoxycoleon U (6,11,12-trihydroxy-5,8,11,13-abietatetraen-7-one) and salviphlomone (6α,7β-dihydroxy-8,13-abietadiene-11,12-dione) were established by chemical and spectroscopic means.

The C-12 and C-20 configurations of some neo-clerodane diterpenoids isolated from Teucrium species

Abstract A convenient and conclusive method for determining the C-12 stereochemistry of neo-clerodan-20,12-olide derivatives, even when only one epimer is available, is by 1 H NMR NOE measurements. The C-12 configuration of 26 neo-clerodane diterpenoids isolated from Teucrium species has been re-examined by using this type of experiment. The results indicated that all the previous assignments were correct, except for teupyreinin, where the previously assigned C-12( S ) configuration must be amended to C-12( R ). This was confirmed by chemical transformations and additional 1 H and 13 C NMR studies. Furthermore, the NOE experiments allowed the assignment of a C-20( S ) configuration for teuflavin, the structure of which had previously been reported without this feature, and indicated that the previously assigned C-20( S ) configuration for teupyreinidin must be amended to C-20( R ). The validity of using NOE experiments to establish the C-12 and C-20 configurations in these neo-clerodane derivatives has been confirmed by applying it to compounds whose structure had already firmly established by X-ray diffraction analyses.

An antimicrobial abietane from the root of Plectranthus hereroensis.

A new abietane diterpene, 16-acetoxy-7 alpha, 12-dihydroxy-8,12-abietadiene-11,14-dione, has been isolated from the acetone extract of the root of Plectranthus hereroensis and its structure established by spectroscopic means. This compound showed antibacterial activity against Staphylococcus aureus and Vibrio cholerae, and antiviral activity against Herpes simplex type II.

Effects of six diterpenes on macrophage eicosanoid biosynthesis.

Six diterpenes (three clerodanes, two abietanes and one rosane) were tested for interactions with the cyclooxygenase and 5-lipoxygenase pathways of arachidonate metabolism and for effects of nitric oxide production. Two abietane diterpenes, aethiopinone and 11,12-dihydroxy-6-oxo-8,11,13-abietatriene and the rosane lagascatriol showed a remarkable effect on COX-1 pathway of PGE2 release in calcium ionophore A23187-stimulated peritoneal macrophages. Only the two latter diterpenes showed inhibition on COX-2 pathway of PGE2 release in E. coli LPS-stimulated peritoneal macrophages. In addition, all compounds assayed were inhibitors of LTC4 release with IC50 < or = 10 microM. Clerodane diterpenes were inactive in COX assay. None of the diterpenes assayed, except 11,12-dihydroxy-6-oxo-8,11,13-abietatriene, affected NO production. The results obtained suggest that the cellular mechanisms of action of some of these substances may involve inhibition of cyclooxygenase/lipoxygenase pathways and nitric oxide production.

Guaiane sesquiterpenes from Teucrium leucocladum

Abstract Three guaiane derivatives have been isolated from the aerial parts of Teucrium leucocladum . Their structures [1α,5β-guai-10(14)-ene-4β,6β-diol (teucladiol), 1α,5β-guaiane-4β,6β,10α-triol (teuclatriol) and 1α,5β-guaiane-4β,6β,10β-triol (10-epiteuclatriol)] were established by 1 H and 13 C NMR spectroscopic studies and by comparison with closely related compounds. In addition, the already known neo -clerodane diterpene montanin C has also been isolated from the same source.

Effects of furocoumarins from Cachrys trifida on some macrophage functions.

Phytochemical and biological studies aimed at the discovery and development of novel antiinflammatory agents from natural sources have been conducted in our laboratory for a number of years. In this communication, three naturally occurring furocoumarins (imperatorin, isoimperatorin and prantschimgin) were evaluated as potential inhibitors of some macrophage functions involved in the inflammatory process. These furocoumarins have been tested in two experimental systems: ionophore‐stimulated mouse peritoneal macrophages serve as a source of cyclooxygenase‐1 and 5‐lipoxygenase, and mouse peritoneal macrophages stimulated with E. coli lipopolysaccharide are the means of testing for anti‐cyclooxygenase‐2 and nitric‐oxide‐synthase activity. All above‐mentioned furocoumarins showed significant effect on 5‐lipoxygenase (leukotriene C4) with IC50 values of < 15 μM. Imperatorin and isoimperatorin exhibited strong‐to‐medium inhibition on cyclooxygenase‐1‐ and cyclooxygenase‐2‐catalysed prostaglandin E2 release, with inhibition percentages similar to those of the reference drugs, indometacin and nimesulide, respectively. Of the three furocoumarins, only imperatorin caused a significant reduction of nitric oxide generation. Imperatorin and isoimperatorin can be classified as dual inhibitors, since it was evident that both cyclooxygenase and lipoxygenase pathways of arachidonate metabolism were inhibited by these compounds. However, selective inhibition of the 5‐lipoxygenase pathway is suggested to be the primary target of action of prantschimgin.

Scutalpin a, a neo-clerodane diterpene from scutellaria alpina

Abstract A new neo -clerodane diterpenoid, scutalpin A, has been isolated from Scutellaria alpina . The structure of scutalpin A [7 β ,19-diacetoxy-6 α -(2′ S )-methylbutyryloxy-4 α ,18; 8 β ,13 S -diepoxy- neo -clerodan-15,16-olide] was established by spectroscopic methods, including an X-ray diffraction analysis which provided its absolute stereochemistry.

Effects ofneo-clerodane diterpenes fromTeucrium on feeding behavior of colorado potato beetle larvae.

Treatment of potato leaf disks with fourneo-clerodane diterpenes fromTeucrium (eriocephalin, teucrin-A, teucvin, and teuscorolide) significantly reduced feeding by larvae ofLeptinotarsa decemlineata (Colorado potato beetle). Choice and no-choice tests suggest that teuscorolide acts as a feeding deterrent, whereas the antifeedant activity of teucrin-A, teucvin, and eriocephalin is likely associated with a toxic mode of action. Nutritional tests, antifeedant simulation assays, and posttreatment studies confirmed that teucrin-A can be categorized by its mode of action as a toxin, rather than as a feeding deterrent.

Structure and Formation of the Fluorescent Compound of Lignum nephriticum

The intense blue fluorescence of the infusion of Lignum nephriticum (Eysenhardtia polystachya), first observed in the sixteenth century, is due to a novel four-ring tetrahydromethanobenzofuro[2,3-d]oxacine which is not present in the plant but is the end product of an unusual, very efficient iterative spontaneous oxidation of at least one of the trees flavonoids.