Nebojsa Ilic

Plants and human health in the twenty-first century

The concept of growing crops for health rather than for food or fiber is slowly changing plant biotechnology and medicine. Rediscovery of the connection between plants and health is responsible for launching a new generation of botanical therapeutics that include plant-derived pharmaceuticals, multicomponent botanical drugs, dietary supplements, functional foods and plant-produced recombinant proteins. Many of these products will soon complement conventional pharmaceuticals in the treatment, prevention and diagnosis of diseases, while at the same time adding value to agriculture. Such complementation can be accelerated by developing better tools for the efficient exploration of diverse and mutually interacting arrays of phytochemicals and for the manipulation of the plants ability to synthesize natural products and complex proteins. This review discusses the history, future, scientific background and regulatory issues related to botanical therapeutics.

Inhibitory effects of grape seed extract on lipases

OBJECTIVE The aim of the present study was to assess the effects of grape seed extract (GSE) on the fat-metabolizing enzymes pancreatic lipase, lipoprotein lipase, and hormone-sensitive lipase in vitro and evaluate its potential application as a treatment for obesity. METHODS Crushed grape seeds were extracted in ethanol, and the extract was assayed for the measurement of inhibitory effects on pancreatic lipase and lipoprotein lipase activities and on lipolysis of 3T3-L1 adipocytes. RESULTS The GSE rich in bioactive phytochemicals showed inhibitory activity on the fat-metabolizing enzymes pancreatic lipase and lipoprotein lipase, thus suggesting that GSE might be useful as a treatment to limit dietary fat absorption and the accumulation of fat in adipose tissue. The observed reduction in intracellular lipolytic activity of cultured 3T3-L1 adipocytes may reduce the levels of circulating free fatty acids that have been linked to insulin resistance in obese patients. CONCLUSION The GSE rich in compounds that inhibit lipases may provide a safe, natural, and cost-effective weight control treatment.

Phytoecdysteroids Increase Protein Synthesis in Skeletal Muscle Cells

Phytoecdysteroids, which are structurally similar or identical to insect molting hormones, produce a range of effects in mammals, including increasing growth and physical performance. To study the mechanism of action of phytoecdysteroids in mammalian tissue, an in vitro cellular assay of protein synthesis was developed. In C2C12 murine myotubes and human primary myotubes, phytoecdysteroids increased protein synthesis by up to 20%. In vivo, ecdysteroids increased rat grip strength. Ecdysteroid-containing plant extracts produced similar results. The effect was inhibited by a phosphoinositide kinase-3 inhibitor, which suggests a PI3K-mediated mechanism.

Indole-3-acetic acid biosynthesis in isolated axes from germinating bean seeds: The effect of wounding on the biosynthetic pathway

A facile radiotracer method for discriminating between the activities oftryptophan-dependent and tryptophan-independent pathways for IAA biosynthesisisdescribed. This method utilized the simultaneous exposure of plants to[14C]anthranilate in the presence or absence of excess unlabeledtryptophan in order to determine if tryptophan feeding can affect the relativeenrichment of the IAA pool. Using this radiotracer method, the activities ofthetwo biosynthetic pathways were analyzed in isolated axes of germinating beanseedlings at various times after cotyledon excision. Unlabeled tryptophansuppressed [14C]anthranilate conversion into IAA in isolated axes ofdifferent ages immediately following cotyledon excision. On the other hand,tryptophan feeding did not inhibit [14C]IAA accumulation in isolatedaxes 36 or 120 h after cotyledon excision. Thus, this method wasable to resolve time-dependent differences following cotyledon excision in thebiosynthetic activities of the two pathways. Moreover, the present results lendfurther support to the emerging consensus that the tryptophan-dependent pathwayacts to maintain very high IAA levels required for mediating rapid cellproliferation in wounded tissues and, as previously shown, young embryos.

Toxicological evaluation of grains of paradise (Aframomum melegueta) [Roscoe] K. Schum.

ETHNOPHARMACOLOGICAL RELEVANCE Grains of Paradise (Aframomum melegueta [Roscoe] K. Schum.) seeds are used in West Africa as a remedy for variety of ailments such as stomach ache, snakebite, diarrhea and they have reported anti-inflammatory properties. Additionally, the seeds contain gingerols and related compounds that may be useful against cardiovascular disease, diabetes, and inflammation. AIM OF STUDY A 28-day sub-chronic toxicity study in male and female Sprague-Dawley rats was conducted to evaluate the safety of a Grains of Paradise extract. MATERIALS AND METHODS An ethanolic extract of the seeds was evaluated for toxicological effect on rats. RESULTS A dose-related increase in absolute and relative liver weights was observed in males and females dosed with 450 and 1500 mg/kg. There was a corresponding increase in alkaline phosphatase with no signs of steatosis or cirrhosis. At the same doses, there was a significant decrease in blood glucose in male rats. CONCLUSIONS This study shows that Grains of Paradise extract may be useful as a treatment for diabetes, however liver toxicity should be considered.

Molecular properties of 4-substituted indole-3-acetic acids affecting pea pericarp elongation

Pea (Pisum sativum L.) fruit naturally contain the auxins, indole-3-acetic acid (IAA) and 4-chloroindole-3-acetic acid (4-Cl-IAA). However, only 4-Cl-IAA can substitute for the seeds in maintaining pea fruit growth in planta. The importance of the substituent at the 4-position of the indole ring was tested by comparing the molecular properties of 4-X-IAA (X = H, Me, Et, F, or Cl) and their effect on the elongation of pea pericarps in planta. Structure-activity is discussed in terms of structural data derived from X-ray analysis, computed conformations in solution, semiempirical shape and bulk parameters, and experimentally determined lipophilicities and NH-acidities. The size of the 4-substituent, and its lipophilicity are associated with growth promoting activity of pea pericarp, while there was no obvious relationship with electromeric effects.

Stable-isotope labeled metabolites of the phytohormone, indole-3-acetic acid

1,3-Dicyclohexylcarbodiimide-mediated condensation of [3a,4,5,6,7,7a-13C6]indole-3-acetic acid with the bis(tert-butyl) esters of L-aspartic or L-glutamic acids, followed by removal of the ester groups by dilute alkali, afforded N-([3a,4,5,6,7,7a-13C6]indol-3-ylacetyl)-L-aspartic and N-([3a,4,5,6,7,7a-13C6]indol-3-ylacetyl)-L-glutamic acids, labeled forms of compounds involved in the regulation of plant growth and development. The corresponding conjugates of (R,S)-2,3-dihydro-2-oxoindole-3-acetic acid, which are likewise of physiological significance, were labeled with 15N in the amino acid moieties and were synthesized via the N-hydroxysuccinimide ester.

Anti-inflammatory activity of grains of paradise (Aframomum melegueta Schum) extract

The ethanolic extract of grains of paradise (Aframomum melegueta Schum, Zingiberaceae) has been evaluated for inhibitory activity on cyclooxygenase-2 (COX-2) enzyme, in vivo for the anti-inflammatory activity and expression of several pro-inflammatory genes. Bioactivity-guided fractionation showed that the most active COX-2 inhibitory compound in the extract was [6]-paradol. [6]-Shogaol, another compound from the extract, was the most active inhibitory compound in pro-inflammatory gene expression assays. In a rat paw edema model, the whole extract reduced inflammation by 49% at 1000 mg/kg. Major gingerols from the extract [6]-paradol, [6]-gingerol, and [6]-shogaol reduced inflammation by 20, 25 and 38%. respectively when administered individually at a dose of 150 mg/kg. [6]-Shogaol efficacy was at the level of aspirin, used as a positive control. Grains of paradise extract has demonstrated an anti-inflammatory activity, which is in part due to the inhibition of COX-2 enzyme activity and expression of pro-inflammatory genes.

Differential inhibition of indole-3-acetic acid and tryptophan biosynthesis by indole analogues. I. Tryptophan dependent IAA biosynthesis

Maize liquid endosperm extracts contain the enzymes necessary for all of the steps of the plant IAA biosynthetic pathway from tryptophan, and provide a means to assay the pathway in vitro. We have analyzed the reactions in the presence of a series of indole and indole-like analogues in order to evaluate the potential of these compounds to act as inhibitors of IAA biosynthesis. Such inhibitors will be useful to investigate the tryptophan to IAA pathway, to determine the precursors and intermediates involved, and to select for mutants in this process. A number of such compounds were tested using in vitro enzyme assays for both the tryptophan dependent IAA biosynthesis pathway and for tryptophan synthase β activity. Some compounds showed strong inhibition of IAA biosynthesis while having only a slight effect on the reaction rate of tryptophan synthase β. These results: (1) show that IAA biosynthesis can be selectively inhibited relative to tryptophan biosynthesis; (2) suggest potential ways to screen for IAA biosynthetic pathway mutations in plants; and (3) provide additional tools for studies of IAA biosynthesis in plants.

Synthesis and conformational analysis of the plant hormone (auxin) related 2-(indol-3-yl)ethyl and 2-phenylethyl β-d-xylopyranosides and their 2,3,4-tri-O-acetyl derivatives

Abstract The synthesis, structure analysis by X-ray diffraction and NMR spectroscopy (including also 1 H 1 HNOE measurements), as well as molecular mechanics and dynamics of d -xylopyranose conjugates of 2-(indol-3-yl)ethanol (1) and 2-phenylethanol ( 2 ) are described. The per- O -acetylated derivatives of 2-(indol-3-yl)ethyl β- d -xylopyranoside (4β) and 2-phenylethyl β- d -xylopyranoside (7β) were prepared [along with corresponding α- d -isomers (4α and 7α) and 1,2- O -orthoacetates (5,8)] by Koenigs-Knorr condensation of the aglycone alcohols with 2,3,4- tri -O- acetyl -α- d - xylopyranosyl bromide. Glycoside 4β was deprotected to yield 2-(indol-3-yl) ethyl β- d -xylopyranoside (6). The crystal structures of 4β and 7β were determined. The crystals of both compounds are monoclinic, space group P 2 1 with a = 11.985(1), b = 7.317(1), c = 12.428(1) A . β = 93.2(1)°, Z = 2 (4β); a = 5.809(1), b = 19.833(1), c = 8.912(1) A , β = 106.0(1)°, Z = 2 (7β) . The β- d -xylopyranose rings are in the 4 C 1 chair conformation. The results of the theoretical conformational analysis are compared with the values obtained from the experimental measurements in solid state and solution.