The microbiological transformation of two 15B-hydroxy-ent-kaurene diterpenes by Gibberella fujikuroi

The incubation of 15B-hydroxy-3-oxo-ent-kaur-16-ene (1) with the fungus Gibberella fujikuroi afforded 11B-hydroxy-3,15-dioxo-ent-kaurane (6), 11B,15B-dihydroxy-3-oxo-ent-kaur-16-ene (8), 7B,11B,15B-trihydroxy-3-oxo-ent-kau-16-ene (9), 7a,11B-dihydroxy-3,15-dioxo-ent-kaurane (7), and 7a,11B,15B-trihidroxy-3-oxo-ent-kaur-16-ene (10). The incubation of 15B-hydroxy-ent-kaur-2,16-diene (3) with the same fungus yielded 7a,11B-dihydroxy-15-oxo-ent-kaur-3-ene (12), 7a,11B,15B-trihydroxy-ent-kaur-2,16-diene (13), 7B,-15B-dihydroxy-ent-kaur-2,16-dien-19,6-olide (14), 1B,7B,15B-trihydroxy-ent-kaur-2,16-dien-19-oic acid (15), 7a,11B,16a-trihydroxy-15-oxo-ent-kaur-2-ene (17), and 7a,15B,17-trihydroxy-11B,16B-epoxy-ent-kaur-2-ene (19). These results indicated that a 3-oxo group in ent-kaur-16-ene derivatives inhibits the oxidation at C-19, typical of the biosynthetic pathway of gibberellins and kaurenolides, while a 2,3-double bond or a 15B-OH does not. In both substrates a 15B-alcohol directs hydroxylations at C-11(B) and C-7(a), while in those with a 2,3-double bond the functionalization of C-1(B) is favored.Peer reviewe

Sesquiterpene lactones from artemisia absinthium. Biotransformation and rearrangement of the insect antifeedant 3α-hydroxypelenolide

Three new compounds, the sesquiterpenes absilactone and hansonlactone and the acetophenone derivative ajenjol, have been isolated from a cultivated variety of Artemisia absinthium. In addition, the major lactone isolated, 3α-hydroxypelenolide, was biotransformed by the fungus Mucor plumbeus affording the corresponding 1β, 10α-epoxide. A cadinane derivative was formed by an acid rearrangement produced in the culture medium, but not by the enzymatic system of the fungus. Furthermore, 3α-hydroxypelenolide showed strong antifeedant effects against Leptinotarsa decemlineata and cytotoxic activity to Sf9 insect cells, while the biotransformed compounds showed antifeedant postingestive effects against Spodoptera littoralis.This work has been supported by grants ERASMUS+ Nº 2018-1-FR01-KA202-047892 Biocontrol E Training (BET) and PID2019-106222RB-C31, MCI, Spai

Bioprospección y diversidad química

17 páginas, 13 tablas y 73 esquemas de compuestos orgánicosUna de las herramientas necesarias para la conservación y el aprovechamiento sostenible de la biodiversidad botánica es el conocimiento de su valor añadido. El contenido en productos naturales bioactivos de las plantas se conoce desde la antigüedad por su valor medicinal y plaguicida. Sin embargo, aún existe un gran desconocimiento de la diversidad química del planeta, agravado por la presión humana sobre la biodiversidad y la consecuente desaparición de especies. Aquí vamos a presentar una pequeña muestra de diversidad química, su valor añadido y posibles soluciones a su aprovechamiento sostenible.Centro de Ciencias Medioambientales- CSIC MadridInstituto de Productos Naturales y Agrobiología - CSIC La Laguna-TenerifeUDI-Fitopatología Fac de Biología - La Laguna-TenerifePeer reviewe

Natural sesquiterpenoids

32 pages, 5 tables, 510 schemes.-- PMID: 19030608 [PubMed].-- Printed version published Dec 2008.This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. 423 references are cited

Natural sesquiterpenoids

This review covers the isolation, structural determination, synthesis and chemical and microbiological transformations of natural sesquiterpenoids. The literature from January to December 2012 is reviewed, and 471 references are cited

Sesquiterpene Lactones from Artemisia absinthium. Biotransformation and Rearrangement of the Insect Antifeedant 3α-hydroxypelenolide

Three new compounds, the sesquiterpenes absilactone and hansonlactone and the acetophenone derivative ajenjol, have been isolated from a cultivated variety of Artemisia absinthium. In addition, the major lactone isolated, 3α-hydroxypelenolide, was biotransformed by the fungus Mucor plumbeus affording the corresponding 1β, 10α-epoxide. A cadinane derivative was formed by an acid rearrangement produced in the culture medium, but not by the enzymatic system of the fungus. Furthermore, 3α-hydroxypelenolide showed strong antifeedant effects against Leptinotarsa decemlineata and cytotoxic activity to Sf9 insect cells, while the biotransformed compounds showed antifeedant postingestive effects against Spodoptera littoralis

Alkene-g-lactones and avocadofurans from persea indica: a revision of the structure of majorenolide and related lactones

Three avocadofurans and an alkene-g-lactone have been isolated from Persea indica. The data for the lactone are similar to those given for majorenolide to which a $-lactone structure was previously assigned. We suggest that its structure and those of other analogous lactones, such as majorynolide and majoranolide, should be revised.Peer reviewe

The dimerisation of 5,6-dimethoxyu-indene

The reaction of 5,6-dimethoxy-indanol with acids or with triphenylphospine-carbon tetrachloride afforded several dimeric compounds; in the dimerisation of 5,6-dimethoxy-indene with SiO2-AgNO3 only a single dimar was obtained.Peer reviewe

The dimerization of precocene I

In an earlier work we reported that treatment of precocene I with Brönsted and Lewis acids produces its oligomerization, giving dimers, trimers, tetramers, etc. Now, in this article we show that bromination of precocene I with phenyltrimethylammonium tribromide (PTT) blocks its oligomerization giving a dibromodimer, which was reduced with tri-n-butyl tin hydride affording the same dimer obtained in the reactions with acid, thus avoiding the oligomerization. Additionally, the oxidations of precocene I with Jones reagent afforded the corresponding 3-hydroxy-4-chromanone, 3,4-chromandione, 3,4-diacid, and two dimers.This work has been supported by grants CTQ2012-38219-C03-01 CTQ2015-64049-C3-1-R, MINECO, Spain.Peer Reviewe

The oligomerization and acylation of precocene I

The oligomerization of precocene I with Brönsted and Lewis acids has been studied. In this way, the reaction of this chromene with HCl/MeOH gave two dimers, a trimer, a linear tetramer and a mixture of pentamers, whilst with FeCl3/HOAc a dimer and six cyclic tetramers were obtained. The cyclization of linear tetramers occurs between C-4‴ and C-6 or, in lower yield, between C-4‴ and C-8. In the formation of linear tetramers the C-8 functionalization was not detected, which could indicate that it occurs during the cyclization process. Moreover, oxidative one-electron coupling reactions were also observed in the treatment of precocene I with FeCl3/HOAc. On the other hand, the reaction of precocene I with FeCl3/Ac2O produced 6-acylation leading to the natural chromene encecalin.This work has been supported by grant CTQ2015-64049-C3-1-R, MINECO, Spain.Peer Reviewe