Biosynthesis of oxindole alkaloids: Recent advances and challenges.

The monoterpenoid oxindole alkaloids (MOA) are specialized plant metabolites of pharmacological importance, whose biosynthesis is linked to a unique oxidative process of monoterpenoid indole alkaloids (MIA). These transformations arise from complex biosynthetic pathways defined by species, organs, tissues, and growth stages. Initial studies of their biosynthesis using labeled precursors date back more than five decades ago.

Induction of Monoterpenoid Oxindole Alkaloids Production and Related Biosynthetic Gene Expression in Response to Signaling Molecules in Plant Cultures.

(Rubiaceae), known as firebush, is a source of bioactive monoterpenoid oxindole alkaloids (MOAs) derived from monoterpenoid indole alkaloids (MIAs). With the aim of understanding the regulation of the biosynthesis of these specialized metabolites, micropropagated plants were elicited with jasmonic acid (JA) and salicylic acid (SA). The MOA production and MIA biosynthetic-related gene expression were evaluated over time.

Mixed elicitation with salicylic acid and hydrogen peroxide modulates the phenolic and iridoid pathways in Castilleja tenuiflora plants.

SA and HO, in single and mixed elicitation stimulate specialized metabolism and activate oxidative stress in C. tenuiflora plants. Single elicitation with salicylic acid (SA at 75 µM) and, hydrogen peroxide (at 150 µM), and mixed elicitation (75 µM SA + 150 µM HO) were evaluated on specialized metabolism in Castilleja tenuiflora Benth.

Fermentation performance of a Mexican native Clavispora lusitaniae strain for xylitol and ethanol production from xylose, glucose and cellobiose.

Lignocellulose hydrolysates are rich in fermentable sugars such as xylose, cellobiose and glucose, with high potential in the biotechnology industry to obtain bioproducts of higher economic value. Thus, it is important to search for and study new yeast strains that co-consume these sugars to achieve better yields and productivity in the processes. The yeast Clavispora lusitaniae CDBB-L-2031, a native strain isolated from mezcal must, was studied under various culture conditions to potentially produce ethanol and xylitol due to its ability to assimilate xylose, cellobiose and glucose.

Nanoemulsified Formulation of Essential Oil and Its Larvicidal Effect against (J.E. Smith).

Cedrela odorata L. is a plant species from the Meliaceae family that is cultivated for timber production. Although the C.

Glucoindole alkaloid accumulation induced by yeast extract in Uncaria tomentosa root cultures is involved in defense response.

Objective: To evaluate the induction of monoterpenoid indole alkaloids (MIA) and phenolic compound production by yeast extract (YE) and its relationship with defense responses in Uncaria tomentosa (Rubiaceae) root cultures.

Results: Root cultures were elicited by YE at three concentrations. The 0.

Expression of a codon-optimized β-glucosidase from Cellulomonas flavigena PR-22 in Saccharomyces cerevisiae for bioethanol production from cellobiose.

Bioethanol is one of the main biofuels produced from the fermentation of saccharified agricultural waste; however, this technology needs to be optimized for profitability. Because the commonly used ethanologenic yeast strains are unable to assimilate cellobiose, several efforts have been made to express cellulose hydrolytic enzymes in these yeasts to produce ethanol from lignocellulose. The C.

Enzymatic saccharification of sugar cane bagasse by continuous xylanase and cellulase production from cellulomonas flavigena PR-22.

Cellulase (CMCase) and xylanase enzyme production and saccharification of sugar cane bagasse were coupled into two stages and named enzyme production and sugar cane bagasse saccharification. The performance of Cellulomonas flavigena (Cf) PR-22 cultured in a bubble column reactor (BCR) was compared to that in a stirred tank reactor (STR). Cells cultured in the BCR presented higher yields and productivity of both CMCase and xylanase activities than those grown in the STR configuration.

Carotenoid production and gene expression in an astaxanthin-overproducing Xanthophyllomyces dendrorhous mutant strain.

The primary carotenoid synthesized by Xanthophyllomyces dendrorhous is astaxanthin, which is used as a feed additive in aquaculture. Cell growth kinetics and carotenoid production were correlated with the mRNA levels of the idi, crtE, crtYB, crtI, crtS and crtR genes, and the changes in gene sequence between the wild-type and a carotenoid overproducer XR4 mutant strain were identified. At the late stationary phase, the total carotenoid content in XR4 was fivefold higher than that of the wild-type strain.

Long-term response on growth, antioxidant enzymes, and secondary metabolites in salicylic acid pre-treated Uncaria tomentosa microplants.

Objective: To obtain micro propagated Uncaria tomentosa plantlets with enhanced secondary metabolites production, long-term responses to salicylic acid (SA) pre-treatments at 1 and 100 µM were evaluated after propagation of the plantlets in a SA-free medium.

Results: SA pre-treatments of single node cuttings OF U. tomentosa produced long-term responses in microplants grown for 75 days in a SA-free medium.

Analysis of proteomic changes in colored mutants of Xanthophyllomyces dendrorhous (Phaffia rhodozyma).

The yeast Xanthophyllomyces dendrorhous synthesizes astaxanthin as its most prevalent xanthophyll derivative. Comparisons between the protein profiles of mutant lines of this yeast can provide insight into the carotenogenic pathway. Differently colored mutants (red, orange, pink, yellow, and white) were obtained from this yeast species, and their protein profiles were determined using two-dimensional polyacrylamide gel electrophoresis (2DE).

Extracellular expression of glucose inhibition-resistant Cellulomonas flavigena PN-120 β-glucosidase by a diploid strain of Saccharomyces cerevisiae.

The catalytic fraction of the Cellulomonas flavigena PN-120 oligomeric β-glucosidase (BGLA) was expressed both intra- and extracellularly in a recombinant diploid of Saccharomyces cerevisiae, under limited nutrient conditions. The recombinant enzyme (BGLA¹⁵) expressed in the supernatant of a rich medium showed 582 IU/L and 99.4 IU/g dry cell, with p-nitrophenyl-β-D-glucopyranoside as substrate.

Strictosidine-related enzymes involved in the alkaloid biosynthesis of Uncaria tomentosa root cultures grown under oxidative stress.

The activity and gene expression of strictosidine-related enzymes in Uncaria tomentosa root cultures exposed to oxidative stress were studied. Elicitation with 0.2 mM hydrogen peroxide (H2 O2 ) or a combination of 0.

Differential alkaloid profile in Uncaria tomentosa micropropagated plantlets and root cultures.

The alkaloids of Uncaria tomentosa micropropagated plantlets and root cultures were isolated and identified by NMR and mass spectrometry. Plantlets yielded pteropodine (1), isopteropodine (2), mitraphylline (3), isomitraphylline (4), uncarine F (5), speciophylline (6), rhynchophylline (7) and isorhynchophylline (8). In plantlets growing under continuous light, tetracyclic alkaloids 7 and 8 decreased from 20 ± 1.

A new monoterpenoid oxindole alkaloid from Hamelia patens micropropagated plantlets.

Chemical studies on Hamelia patens (Rubiaceae) micropropagated plantlets allowed production of a new monoterpenoid oxindole alkaloid, named (-)-hameline (7), together with eight known alkaloids, tetrahydroalstonine (1), aricine (2), pteropodine (3), isopteropodine (4), uncarine F (5), speciophylline (6), palmirine (8), and rumberine (9). The structure of the new alkaloid was assigned on the basis of 1D and 2D NMR spectroscopy, mass spectrometry, and molecular modeling.

Production of cellulases and xylanases under catabolic repression conditions from mutant PR-22 of Cellulomonas flavigena.

Derepressed mutant PR-22 was obtained by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) mutagenic treatment of Cellulomonas flavigena PN-120. This mutant improved its xylanolytic activity from 26.9 to 40 U mg(-1) and cellulolytic activity from 1.

Short-term accumulation of atrazine by three plants from a wetland model system.

This work describes the accumulation and distribution of the herbicide atrazine in soil, water, and roots from three wetland model systems using the monocots Typha domingensis, Sagittaria lancifolia, and Echinochloa pyramidalis. Results were analyzed from a 3(3) full factorial experimental design, in order to describe the effect of accumulation of atrazine and times of exposure in the species evaluated. We found that accumulation depends on the species and the herbicide concentration; about 30% was accumulated in soil, 40% in roots, and 10-20% in water.

Differential expression of cellulases and xylanases by Cellulomonas flavigena grown on different carbon sources.

The diversity of cellulases and xylanases secreted by Cellulomonas flavigena cultured on sugar cane bagasse, Solka-floc, xylan, or glucose was explored by two-dimensional gel electrophoresis. C. flavigena produced the largest variety of cellulases and xylanases on sugar cane bagasse.

Characterization of a beta-glucosidase produced by a high-specific growth-rate mutant of Cellulomonas flavigena.

The mutant strain PN-120 of Cellulomonas flavigena produces a ss-glucosidase that is 10-fold more active than the corresponding enzyme isolated from the parental strain. These enzymes were partially purified through Q Sepharose and Bio-Gel filtration. A single protein band was detected on polyacrylamide-gel electrophoresis/zymogram using 4-methylumbelliferyl-beta-D-glucoside.

Hydrodynamic stress induces monoterpenoid oxindole alkaloid accumulation by Uncaria tomentosa (Willd) D. C. cell suspension cultures via oxidative burst.

Uncaria tomentosa cell suspension cultures were grown in a 2-L stirred tank bioreactor operating at a shear rate gamma(.)(avg)=86 s(-1). The cultures showed an early monophasic oxidative burst measured as H2O2 production (2.

Induced accumulation of oleanolic acid and ursolic acid in cell suspension cultures of Uncaria tomentosa.

Increasing sucrose from 20 to 50 g l(-1) in Uncaria tomentosa cell suspension cultures enhanced ursolic acid and oleanolic acid production from 129 +/- 61 to 553 +/- 193 microg g(-1) cell dry wt. The maximal concentration of both triterpenes (1680 +/- 39 microg g(-1) cell dry wt) was 8 days after elicitation by jasmonic acid, while yeast extract or citrus pectin treatments produced 1189 +/- 20 or 1120 +/- 26 microg g(-1) cell dry wt, respectively. The ratio of ursolic acid:oleanolic acid was constant at 70:30.

Monoterpenoid oxindole alkaloid production by Uncaria tomentosa (Willd) D.C. cell suspension cultures in a stirred tank bioreactor.

Cell growth, monoterpenoid oxindole alkaloid (MOA) production, and morphological properties of Uncaria tomentosa cell suspension cultures in a 2-L stirred tank bioreactor were investigated. U. tomentosa (cell line green Uth-3) was able to grow in a stirred tank at an impeller tip speed of 95 cm/s (agitation speed of 400 rpm), showing a maximum biomass yield of 11.

Influence of auxins and sucrose in monoterpenoid oxindole alkaloid production by Uncaria tomentosa cell suspension cultures.

Growth and alkaloid production in Uncaria tomentosa cell suspension cultures were studied in Murashige and Skoog medium supplemented with 10 microM 2,4-dichlorophenoxyacetic acid, 10 microM kinetin, and 58 mM sucrose for maintenance and with 10 microM indole-3-acetic acid, 10 microM kinetin, and 58 mM sucrose for production. A U. tomentosa pale Uth-3 cell line, cultured in the production medium, showed a reduced lag phase and a specific growth rate (mu) of 0.

Production of alkaloids by in vitro culture of Erythrina americana Miller.

The production of erythroidines and other alkaloids was studied in cotyledons, callus and cell suspension cultures of Erythrina americana Miller. The cell suspension cultures, grown in Murashige & Skoog medium with naphthaleneacetic acid (3 mg l(-1)) and kinetin (2 mg l(-1)), produced 89 and 17 microg alpha- and beta-erythroidines respectively per g dry wt.

Identification of lethal mutations in Escherichia coli genes encoding enzymes of the methylerythritol phosphate pathway.

The recently elucidated methylerythritol phosphate (MEP) pathway for isoprenoid biosynthesis is essential in eubacteria (including Escherichia coli), the malaria parasite, and plants, but is absent in animals. Therefore, the pathway enzymes are promising targets for the development of novel herbicides and antimicrobials that are potentially innocuous for humans. For an effective drug design, it is important to identify the residues required to preserve the structure and activity of the MEP pathway enzymes.