Diogo Denardi Porto

The Alkaloid Brachycerine is Induced by Ultraviolet Radiation and is a Singlet Oxygen Quencher

Abstract The effects of ultraviolet (UV) radiation on chlorophyll content and accumulation of the anti-inflammatory monoterpene-indole alkaloid brachycerine in plants and calli of Psychotria brachyceras (Rubiaceae) were investigated. In this study, we also investigated a protective role for brachycerine against stress conditions. Calli and tip cuttings incubated in nutrient media were daily supplemented with 4 or 16 h of UV. High-performance liquid chromatography analyses of methanolic extracts showed only traces of brachycerine in irradiated aseptic cultures, with no alkaloid being observed in control calli. In cuttings, a 10-fold increase in brachycerine content was seen after exposure for 16 h to UV-C, whereas a 4 h daily supplementation doubled the amount of the alkaloid in leaves. Exposure to a UV-B source also doubled the alkaloid yield. In vitro brachycerine was able to quench singlet oxygen. The data indicate a potential protective role for brachycerine against UV radiation, acting as a UV filter (absorption peaks are within the UV range) and a reactive oxygen species scavenger. In addition, UV radiation may be used to increase yields of this compound of pharmaceutical interest.

ENVIRONMENTAL AND ONTOGENETIC CONTROL OF ACCUMULATION OF BRACHYCERINE, A BIOACTIVE INDOLE ALKALOID FROM Psychotria brachyceras

Brachycerine is a monoterpenoid indole alkaloid accumulated in Psychotria brachyceras plants (Rubiaceae). To better understand the accumulation patterns of this alkaloid, we investigated its content in different plant organs from field-grown trees, throughout the seasons, during seedling development, and in response to potential biotic factors regulating its biosynthesis. Quantification by RP-HPLC showed that aerial vegetative organs (green stems, young and old leaves) yielded similar amounts of brachycerine [0.1–0.2% dry weight (DW)]. Brachycerine was not detected in roots. In reproductive structures, the highest brachycerine amounts (0.3% DW) were found in inflorescences. Alkaloid concentration decreased in mature fruits (0.045% DW). The lowest concentration in reproductive organs was observed in quiescent seeds (0.004% DW). Apparently, brachycerine content dropped during radicle emission in germinating seeds. During seedling development, an increase in leaf content from 0.02 to 0.1% DW was observed between the stages of 2 and 14 leaves, respectively. Salicylic acid did not affect brachycerine content. A doubling of alkaloid content was observed in wounded plants, and a threefold induction occurred with jasmonic acid treatment, suggesting that brachycerine biosynthesis is regulated by jasmonate production.

Bioactive Alkaloids from South American Psychotria and Related Species

Many important molecules have been discovered from tropical and sub-tropical plant biodiversity. However, the largest part of the chemical profile of such biodiversity remains unknown. Combining ethnopharmacological and chemotaxonomical investigation can be a good strategy in bioactive compound discovery. South American Psychotria species studied by this approach proved to be a rich source of new bioactive alkaloids, some of which bear unique chemi- cal skeletons.

Transcriptome analyses of the Dof-like gene family in grapevine reveal its involvement in berry, flower and seed development.

The Dof (DNA-binding with one finger) protein family spans a group of plant transcription factors involved in the regulation of several functions, such as plant responses to stress, hormones and light, phytochrome signaling and seed germination. Here we describe the Dof-like gene family in grapevine (Vitis vinifera L.), which consists of 25 genes coding for Dof. An extensive in silico characterization of the VviDofL gene family was performed. Additionally, the expression of the entire gene family was assessed in 54 grapevine tissues and organs using an integrated approach with microarray (cv Corvina) and real-time PCR (cv Pinot Noir) analyses. The phylogenetic analysis comparing grapevine sequences with those of Arabidopsis, tomato, poplar and already described Dof genes in other species allowed us to identify several duplicated genes. The diversification of grapevine DofL genes during evolution likely resulted in a broader range of biological roles. Furthermore, distinct expression patterns were identified between samples analyzed, corroborating such hypothesis. Our expression results indicate that several VviDofL genes perform their functional roles mainly during flower, berry and seed development, highlighting their importance for grapevine growth and production. The identification of similar expression profiles between both approaches strongly suggests that these genes have important regulatory roles that are evolutionally conserved between grapevine cvs Corvina and Pinot Noir.