Isolation and characterization of pentadin, the sweet principle of Pentadiplandra brazzeana Baillon

An aqaeous extract from the pulp of the plant Pentadiplandrabrazzeana Baillon (Pentadiplandraceae) yielded a strong sweet-tastingmaterial. This sweet principle was isolated by water extraction,ultrafiltration and gel filtration. The conclusion that thissubstance must be of a proteinaceous nature was based on aminoacid analysis, characteristic UV-absorption spectrum and positivecolour reaction with Coomassie brilliant blue. The mol. wt ofthe subunit of the sweet protein was estimated to be {smalltilde} 12 000 daltons. The sweetness intensity of the wholeprotein was {small tilde} 500 times that of sucrose on a weightbasis. The taste response in a Rhesus monkey to a 0.1 % solutionwas comparable to the response to a 0.02 % monellin solution.We propose the name ‘pentadin’ for this sweet-tastingprotein and present a few comments about the possible originof such sugar mimics.     

Potent Natural Soluble Epoxide Hydrolase Inhibitors from Pentadiplandra brazzeana Baillon: Synthesis,Quantification, and Measurement of Biological Activities In Vitro and In Vivo

We describe here three urea-based soluble epoxide hydrolase (sEH) inhibitors from the root of the plant Pentadiplandra brazzeana. The concentration of these ureas in the root was quantified by LC-MS/MS, showing that 1, 3-bis (4-methoxybenzyl) urea (MMU) is the most abundant (42.3 μg/g dry root weight). All of the ureas were chemically synthesized, and their inhibitory activity toward recombinant human and recombinant rat sEH was measured. The most potent compound, MMU, showed an IC₅₀ of 92 nM via fluorescent assay and a Ki of 54 nM via radioactivity-based assay on human sEH. MMU effectively reduced inflammatory pain in a rat nociceptive pain assay. These compounds are among the most potent sEH inhibitors derived from natural sources. Moreover, inhibition of sEH by these compounds may mechanistically explain some of the therapeutic effects of P. brazzeana.     

Role of glucosinolates in plant invasiveness

Many plants have been intentionally or accidentally introduced to new habitats where some of them now cause major ecological and economic threats to natural and agricultural ecosystems. The potential to become invasive might depend on plant characteristics, as well as on specific interactions with other organisms acting as symbionts or antagonists, including other plants, microbes, herbivores, or pollinators. The invasion potential furthermore depends on abiotic conditions in the habitat. Several species of the Brassicaceae, well known for their glucosinolate–myrosinase defence system, are invasive species. Various factors are reviewed here that might explain why these species were so successful in colonising new areas. Specific emphasis is laid on the role of glucosinolates and their hydrolysis products in the invasion potential. This particular defence system is involved specifically in plant–plant, plant–microbe and plant–insect interactions. Most research has been done on the mechanisms underlying invasion success of Alliaria petiolata and Brassica spp., followed by Bunias orientalis and Lepidium draba. Some examples are also given for plants that are not necessarily considered as invasives, but which were well investigated with respect to their interference potential with their biotic environment. For each species, most likely a combination of different plant characteristics enhanced the competitive abilities and led to diverse invasive phenotypes.     

Thermal degradation of glucosinolates

Three glucosinolates (allyl-, benzyl- and 2-phenethyl-) were shown to degrade thermally in a GC column to yield products identical with those obtained conventionally on enzymic decomposition, namely nitriles and isothiocyanates. Nitriles were formed more readily at 125° but the facility for isothiocyanate production varied slightly with the glucosinolate; 2-phenethylglucosinolate was the most labile of those studied yielding isothiocyanate at a column temperature of 150°. Temperature was confirmed as the cause of degradation by isolated heated-tube experiments. The results have significance both with regard to analytical methodology for glucosinolates and their products, and with regard to furthering understanding of the mechanisms of glucosinolate degradation.     

Biosynthesis and metabolic engineering of glucosinolates

Summary. Glucosinolates are amino acid-derived natural plant products found throughout the Capparales order. Glucosinolates and their degradation products have a wide range of biological activities, e.g. in plant defense as deterrents against insect and fungi. The conversion of amino acids to aldoximes is a key step in glucosinolate biosynthesis. This step is catalyzed by cytochromes P450 from the CYP79 family. The post-aldoxime enzymes in the glucosinolate pathway have high substrate-specificity for the functional group and low substrate-specificity for the side chain. Therefore, we have been able to metabolically engineer new glucosinolate profiles into Arabidopsis by altering the levels of endogenous CYP79s and by introducing exogenous CYP79s. The approach has great potential for design of metabolically engineered plants with improved pest resistance and increased nutritional value. Received December 7, 2001 Accepted December 21, 2001     

Failure to detect glucosinolates in cocoa

Dehulled cocoa beans and hulls of cocoa beans, Theobroma cacao L., have been examined for a supposed content of glucosinolates. Different methods of glucosinolate analysis have been used for investigations of the anion-containing fractions but no glucosinolates (detection limit 1 nmol/g) could be detected. The significance of the results obtained is briefly discussed.     

Long-distance phloem transport of glucosinolates in Arabidopsis

Glucosinolates are a large group of plant secondary metabolites found mainly in the order Capparales, which includes a large number of economically important Brassica crops and the model plant Arabidopsis. In the present study, several lines of evidence are provided for phloem transport of glucosinolates in Arabidopsis. When radiolabeled p-hydroxybenzylglucosinolate (p-OHBG) and sucrose were co-applied to the tip of detached leaves, both tracers were collected in the phloem exudates at the petioles. Long-distance transport of [(14)C]p-OHBG was investigated in wild-type and transgenic 35S::CYP79A1 plants, synthesizing high amounts of p-OHBG, which is not a natural constituent of wild-type Arabidopsis. In both wild-type and 35S::CYP79A1 plants, radiolabeled p-OHBG was rapidly transported from the application site into the whole plant and intact p-OHBG was recovered from different tissues. The pattern of distribution of the radioactivity corresponded to that expected for transport of photoassimilates such as sucrose, and was consistent with translocation in phloem following the source-sink relationship. Radiolabeled p-OHBG was shown to accumulate in the seeds of wild-type and 35S::CYP79A1 plants, where p-OHBG had been either exogenously applied or endogenously synthesized from Tyr in the leaves. p-OHBG was found in phloem exudates collected from cut petioles of leaves from both wild-type and 35S::CYP79A1 plants. Phloem exudates were shown to contain intact glucosinolates, and not desulphoglucosinolates, as the transport form. It is concluded that intact glucosinolates are readily loaded into and transported by the phloem.     

The phloem mobility of glucosinolates

The transport properties of glucosinolates within Brassica napus are of interest as identification of the mechanism of transport could lead to lower levels being obtained in specific tissues such as the seeds. The phloem mobility of ³⁵S-gluconapin (but-3-enylglucosinolate) and ³⁵S-desulphogluconapin in oilseed rape plants has been inferred from tissue distribution patterns, as well as from observed coincident phloem mobility of ³H-gluconapin and ¹⁴C-sucrose. The measured relative phloem mobilities for sinigrin (2-propenylglucosinolate), ³H-gluconapin, ³⁵S-desulphogluconapin, ³⁵S-desulphosinigrin, ¹⁴C-tryptophan, ³H-AIB (-aminoisobutyric acid), and literature values for a reduced ³H-oligogalacutonide elicitor (degree of polymerization 6) and ¹⁴C-IAA (indolylacetic acid), have been compared with the predicted values obtained using the Kleier model for phloem mobility of xenobiotics. All the above compounds show phloem systemicity, demonstrated using the Ricinus assay, as predicted by the model. Log Kow (octanol-water partition coefficient) values for glucosinolates and desulphoglucosinolates measured at pH 4 and pH 7, and the effect of pH on uptake by oilseed rape embryos are provided as evidence against a weak acid trap mechanism acting in either the phloem mobility or the accumulation of glucosinolates in oilseed rape embryos. The phloem mobility of glucosinolates is explained by the intermediate permeability hypothesis. In conclusion, it would appear that glucosinolates like other groups of endogenous compounds have physicochemical properties allowing phloem mobility as predicted by the Kleier model.Keywords: Brassica napus, Ricinus communis, phloem mobility, glucosinolates, Kleier model.      

Synthesis and anti-inflammatory activity of indole glucosinolates

The nitronate and nitrovinyl methods to synthesize indole glucosinolates (GLs) have been investigated. The results were applied to generally the most prevalent natural indole glucosinolates to synthesize 4-methoxyglucobrassicin (MGB) and neo-glucobrassicin (NGB) in moderate overall yield for the first time. The anti-inflammatory activity of the synthetic indole GLs was determined by inhibition of TNF-α secretion in LPS-stimulated THP-1 cells. The data showed that glucobrassicin (GB) exhibited higher activity than other synthetic indolyl GLs.     

Composition and content of glucosinolates in developing Arabidopsis thaliana

The glucosinolate composition and content in various tissues of Arabidopsis thaliana (L.) Heynh. ecotype Columbia during development from seeds to bolting plants were determined in detail by high-performance liquid chromatography. Comparison of the glucosinolate profiles of leaves, roots and stems from mature plants with those of green siliques and mature seeds indicated that a majority of the seed glucosinolates were synthesized de novo in the silique. A comparison of the glucosinolate profile of mature seeds with that of cotyledons indicated that a major part of seed glucosinolates was retained in the cotyledons. Turnover of glucosinolates was studied by germination of seeds containing radiolabelled p-hydroxybenzylglucosinolate (p-OHBG). Approximately 70% of the content of [14C]p-OHBG in the seeds was detected in seedlings at the cotyledon stage and [14C]p-OHBG was barely detectable in young plants with rosettes of six to eight leaves. The turn-over of p-OHBG was found to coincide with the expression of the glucosinolate-degrading enzyme myrosinase, which was detectable at very low levels in seedlings at the cotyledon stage, but which dramatically increased in leaves from plants at later developmental stages. This indicates that there is a continuous turnover of glucosinolates during development and not only upon tissue disruption.     

Synthesis and anti-inflammatory activity of aromatic glucosinolates

Aromatic GLs are important members of the glucosinolate family of compounds because of their potential biological activity and medicinal properties. This study has shown success in the high yielding synthesis of some important aromatic GLs as well as the results of testing for anti-inflammatory properties of the synthetic GLs. 3,4-Dimethoxyphenylglucosinolate was found to be the most active anti-inflammatory of the seven glucosinolates assayed.     

Determination and quantification of sinigrin glucosinolates in Alternaria solani susceptible tomato (Solanum lycopersicum) leaves treated with moringa (Moringa oleifera) leaf extract

Abstract

The study investigates the presence and quantity of antimicrobial sinigrin glucosinolates in tomato leaves after spraying them with moringa (Moringa oleifera) leaf extract (MLAE). Moringa concentrates (0.5, 0.75, 1.00 and 1.5?kg?L^?1 (w v^?1)) were prepared. Distilled water was the control. Sampled tomato leaves were air-dried, freeze-dried and extracted firstly using pure methanol in a hot water bath and then pellet re-extracted using 5?mL of hot aqueous methanol (70% v v^?1). An ion exchange column, and sulphatase was used to achieve glucosiodesulphonation. High performance liquid chromatography (HPLC) was employed in the identification and quantitative analysis of the sinigrin glucosinolates. Tomato (Solanum lycopersicum) leaves treated with MLAE revealed highly significant (p?<?.001) content of sinigrin glucosinolates. The sinigrin standard and the desulphated sinigrin glucosinolates had a 7?s retention time difference; 5?kg?L^?1 (w v^?1) resulted in a superior amount of sinigrin in tomato leaves as compared to all the other MLAE concentrations. The study reveals that spraying MLAE on putatively diseased tomato leaves donates specific quantifiable glucosinolates like sinigrin, which may be involved in defense against tomato diseases and, hence, recommends use of 5?kg?L^?1 (w v^?1) for the highest sinigrin defense tag.     

Chemical profile and biological activities of Cedrelopsis grevei H. Baillon bark essential oil

Cedrelopsis grevei H. Baillon bark, endemic plant from Madagascar, is used in folk medicine for the treatment of rheumatism, muscular pain, and for its antifungal and antibiotic activities. In this paper, the phytochemical composition, antioxidant, antimicrobial, and cytotoxic activities of C. grevei bark essential oil (EO), its non-polar (I and II) and polar (III) fractions and its main compounds (ishwarane, β-elemene and α-copaene) were investigated.

The GC–MS analysis pointed out the presence of 36 components, representing about 80% as semi-quantitative characterization of the total. The presence of ishwarane, β-elemene and α-copaene as the main constituents highlighted its peculiar composition as a sesquiterpene-rich phytocomplex. Moreover, the quantification was performed for the first time by means of the experimental and predicted response factors (ERFs and PRFs, respectively).

As regards the biological activity, C. grevei EO and its fractions showed weak antioxidant activity against Trolox. The whole EO demonstrated instead considerable antimicrobial activity against Staphylococcus aureus and Staphylococcus epidermidis, while its polar-fraction evidenced an interesting bioactivity against Pseudomonas aeruginosa and Candida albicans. Finally, C. grevei EO and its fractions exhibited an interesting cytotoxic activity on human lung cancer cells (A549) and human colorectal cancer cells (CaCo-2).     

芥子油苷在植物-生物环境关系中的作用

芥子油苷是一类含氮、含硫的植物次生代谢物质,主要分布于白花菜目的十字花科植物。芥子油苷及其降解产物具有多种生化活性,近年来人们更多地关注芥子油苷代谢与其它物质代谢途径的相互联系以及与植物生存环境的相互作用。介绍了芥子油苷及其分布、芥子油苷-黑芥子酶系统以及由芥子油苷介导的植物对昆虫、病原体的防御作用和植物与植物之间的化感作用的研究概况。     

Distribution and chemotaxonomic significance of glucosinolates in certain Middle-Eastern cruciferae

Eighty-four collections of 51 species of Middle-eastern Cruciferae were analysed by paper and gas-liquid chromatography for seed glucosinolates. Thirty-two species were investigated for the first time. Thirty compounds were identified and three unknowns of limited occurrence were found, p-Hydroxybenzylglucosinolate was found in six species of various tribes. 4-Methylsulfinyl-3-butenyl, 3-methoxycarbonylpropyl, and p-rhamnopyranosyloxybenzyl glucosinolates, which are rare in the Cruciferae, were found in Sinapis aucheri two species of Erysimum and Thlaspi perfoliatum, respectively. The biosynthetic precursors of all but one of the 30 glucosinolates are protein amino acids and at least 20 glucosinolates are derived from methionine. The distribution of glucosinolates is very useful at the species and genus levels but may provide only minimal support to the tribal alliance of certain genera. It supports the removal of Sinapis aucheri from the genus, the recognition of Fibigia clypeata and F. macrocarpa as distinct species, and the alliance of Ochthodium with Euclidium and Arabis with Drabopsis.     

Survey of aliphatic glucosinolates in Sicilian wild and cultivated Brassicaceae

In the frame of the activities carried out to exploit Sicilian local cultivars of brassicas, we focused our attention on some of the potential health compounds of various local cruciferous crops. These compounds are of interest to improve the quality of the produce with the aim to develop new cultivars capable of providing functional foods able to prevent disease. In this context, we surveyed for the presence of specific glucosinolates in local cultivars of broccoli, cauliflower, kale, and in some wild species widespread in Sicily, using as control various commercial cultivars. Glucosinolate composition varied extensively among species and crops of the same species, such as cauliflower, broccoli and kale. Cultivar variation for glucosinolate profile was also observed for some crops. For example, Sicilian cultivars of cauliflower possessing colored curds displayed a high content of glucosinolates, glucoraphanin in particular, compared to white curd commercial cultivars. Also some wild species had a high content of other glucosinolates.     

The enzymic and chemically induced decomposition of glucosinolates

While the myrosinase-glucosinolate system has been reviewed in recent years by a number of authors, little attention has been paid to the enzymic and non-enzymic degradation of glucosinolates. Non-enzymic degradation processes are particularly important in the processing of brassica vegetables with respect to both flavour and in the role of glucosinolates as precursors of anticancer compounds in the diet. This review highlights early empirical work on glucosinolate degradation along with more recent aspects related to current research on mechanism of glucosinolate degradation in plants, microbes and animals.     

Variation of glucosinolates in vegetable crops of Brassica rapa

Glucosinolate levels in leaves were determined in a collection of 113 varieties of turnip greens (Brassica rapa L.) from northwestern Spain grown at two sites. Sensorial attributes were also assessed by a consumer panel. The objectives were to determine the diversity among varieties in total glucosinolate content and glucosinolate profile and to evaluate their sensory attributes in relation to glucosinolate content for breeding purposes. Sixteen glucosinolates were identified, being the aliphatic glucosinolates, gluconapin and glucobrassicanapin the most abundant. Other aliphatic glucosinolates, such as progoitrin, glucoalyssin, and gluconapoleiferin were relatively abundant in varieties with a different glucosinolate profile. Indolic and aromatic glucosinolate concentrations were low and showed few differences among varieties. Differences in total glucosinolate content, glucosinolate profile and bitterness were found among varieties, with a total glucosinolate content ranging from 11.8 to 74.0micromolg(-1) dw at one site and from 7.5 to 56.9micromolg(-1) dw at the other site. Sensory analysis comparing bitterness with variation in glucosinolate, gluconapin and glucobrassicanapin concentrations suggested that these compounds and their breakdown products are not the only determinants of the characteristic flavour of this vegetable. Other phytochemicals are probably involved on the characteristic bitter flavour. The varieties MBG-BRS0132, MBG-BRS0082, MBG-BRS0173, and MBG-BRS0184 could be good candidates for future breeding programs since they had high total glucosinolate content and good agronomic performance. The presence of glucoraphanin in some varieties should be studied more extensively, because this aliphatic glucosinolate is the precursor of sulforaphane, a potent anti-cancer isothiocyanate.