Ehab A. Abourashed

The inhibitory activity of natural products on plant p-hydroxyphenylpyruvate dioxygenase.

The inhibitory activity of 34 natural products of various structural classes on hydroxyphenylpyruvate dioxygenase (HPPD), the target site for triketone herbicides, and the mode of interaction of selected natural products were investigated. Recombinant HPPD from arabidopsis is sensitive to several classes of natural compounds including, in decreasing order of sensitivity, triketones, benzoquinones, naphthoquinones and anthraquinones. The triketone natural products acted as competitive tight-binding inhibitors, whereas the benzoquinones and naphthoquinones did not appear to bind tightly to HPPD. While these natural products may not have optimal structural features required for in vivo herbicidal activity, the differences in their kinetic behavior suggest that novel classes of HPPD inhibitors may be developed based on their structural backbones.

Interactions of valerian extracts and a fixed valerian–hop extract combination with adenosine receptors

Phytopharmaceuticals and dietary supplements containing valerian are used as mild sleep-inducing agents. An in vitro radioligand binding assay at A(1) and A(2A) adenosine receptors (ARs) was conducted with a fixed extract combination of valerian and hop (Ze 91019) to investigate a possible mechanism for the pharmacological activity of the extract. Component extracts of valerian and hop were also individually investigated. The fixed combination Ze 91019 as well as the valerian extracts therein exhibited selective affinity to A(1)ARs (K(i) = 0.15-0.37 mg/mL vs [(3)H]CCPA). The same extracts exhibited partial agonist activity at the A(1) adenosine receptor as indicated by a lower degree of stimulation of [35S]GTP gamma S binding in membrane preparations of CHO-hA(1) cells as compared to the full A(1) AR agonist N(6)-cyclopentyladenosine (CPA). In addition valerian extract inhibited cAMP accumulation in CHO-hA(1) cell membranes. The partial agonistic activity at A(1)ARs may thus play a role in the sleep inducing effect of Ze 91019 and the valerian extract therein.

Phytochemical and biological studies on Saudi Commiphora opobalsamum L.

The aerial part of Commiphora opobalsamum L. (Burseraceae) growing in Saudi Arabia was subjected to a phytopharmacological investigation in order to identify its major chemical constituents and to evaluate its extracts and isolated compounds in preliminary in vitro assays for antimicrobial, antimalarial, antitumor, anti-inflammatory (COX-2 inhibition), antioxidant and estrogenic activity. Six compounds were isolated and identified as the triterpenes friedelin, canophyllal, and oleanonic acid; the flavonols mearnsetin and quercetin; and syringic acid. The ethyl acetate extract was moderately active against Staphylococcus aureus, Pseudomonas aeruginosa, and Plasmodium falciparum; while the petroleum ether and chloroform extracts inhibited COX-2 at 5 and 10 µg mL−1, respectively. Of the isolated compounds, syringic acid showed moderate antimalarial, anticandidal, and antimycobacterial activity; while mearnsetin and quercetin exhibited antioxidant activity comparable to ascorbic acid and trolox. This is the first detailed phytochemical investigation of C. opobalsamum L. growing in Saudi Arabia and elsewhere. The isolated compounds are reported from this plant for the first time and their full 1H and 13C NMR assignments are included.

Clinic at the health food store? Employee recommendations and product analysis

Study Objectives. To determine what products health food store employees recommend for depression, to analyze the content of these products based on label claims, and to evaluate employee statements or recommendations for accuracy and safety.

High-Speed Extraction and HPLC Fingerprinting of Medicinal Plants – I. Application to Passiflora Flavonoids

An approach comprising accelerated solvent extraction followed by quantitative HPLC analysis has been adopted in fingerprinting 115 samples of different species of the genus Passiflora. The C-flavonoid glycosides schaftoside (1), isoschaftoside (2), isoorientin (3), orientin (4), isovitexin (5) and vitexin (6) were chosen as analytical standards and their overall prevalence in all samples was determined. The developed HPLC method utilizes gradient elution on an analytical Phenomenex Hypersil ODS column and UV detection at 280 nm. The availability of unique fingerprints, as well as quantitative data, for each species can provide a number of benefits including, but not limited to (a) authentication of samples, (b) determination of chemotaxonomic markers, (c) identification of constituent patterns related to specific geographical locations, (d) supportive data in genetic studies, (e) identifying possible substitutes for Passiflora incarnata, (f) differentiating between closely related species, and (g) relating biological activities to phytochemical profiles.

BIOCONVERSION OF SILYBIN TO PHASE I AND II MICROBIAL METABOLITES WITH RETAINED ANTIOXIDANT ACTIVITY

Microbial transformation of silybin (1), the major flavonolignan of milk thistle (Silybum marianum, Asteraceae), resulted in the isolation of four metabolites. The structures of the isolated metabolites were determined by spectroscopic methods. One phase I metabolite was produced by Beauveria bassiana and was characterized as 8-hydroxysilybin (2). Three phase II metabolites were produced by two Cunninghamella species and were identified as 2,3-dehydrosilybin-3-O-β-d-glucoside (3), obtained from Cunninghamella species; and silybin-7-sulfate (4) and 2,3-dehydrosilybin-7-sulfate (5), obtained from Cunninghamella blakesleana. Compared to 1 (IC(50) 284 μg/mL), the generated metabolites displayed varying levels of antioxidant activities in the DPPH free-radical scavenging assay.

Towards a better understanding of the psychopharmacology of nutmeg: Activities in the mouse tetrad assay

ETHNOPHARMACOLOGICAL RELEVANCE Nutmeg, the seeds of Myritica fragrans (family Myristicaceae), is a well known kitchen spice with a long-standing reputation as a psychoactive herb. Nutmeg at high doses is considered a cheap substitute to several drugs of abuse. Earlier reports have attributed amphetamine-like activities to nutmeg. AIM OF THE STUDY To characterize the neuropharmacological effects of different nutmeg extracts, administered orally and intraperitoneally, in comparison to Delta(9)-terahydrocannabinol, amphetamine, and morphine. MATERIALS AND METHODS Methanolic (ME), dichloromethane (DE), and hexane (HE) extracts were obtained from a chromatographically fingerprinted batch of nutmeg. Biological evaluation was conducted in sets of 6-8 mice in the tetrad assay at doses ranging from 100 to 500 and 500 to 1000 mg/kg for i.p. and oral administration, respectively. RESULTS While oral administration of all the nutmeg extracts at 500 mg/kg caused a significant increase in locomotor activity, the i.p. administration of DE showed significant reduction in rectal temperature along with a significant increase in tail flick latency at 300 mg/kg. A significant decrease in core body temperature was observed with HE at 100 mg/kg, while higher doses caused significant increases in hot plate latency. CONCLUSION Different behavioral effects were observed that varied by the type of extract as well as by the route of administration.

Bioavailability of Plant-Derived Antioxidants

Natural products with antioxidant properties have been extensively utilized in the pharmaceutical and food industry and have also been very popular as health-promoting herbal products. This review provides a summary of the literature published around the first decade of the 21st century regarding the oral bioavailability of carotenoids, polyphenols and sulfur compounds as the three major classes of plant-derived antioxidants. The reviewed original research includes more than 40 compounds belonging to the above mentioned classes of natural antioxidants. In addition, related reviews published during the same period have been cited. A brief introduction to general bioavailability-related definitions, procedures and considerations is also included.

HPTLC determination of sildenafil in pharmaceutical products and aphrodisiac herbal preparations

A high-performance thin-layer chromatographic (HPTLC) method has been established for determination of sildenafil citrate in commercial products. The compounds were separated on silica gel, with CHCl3-MeOH-diethylamine, 90 + 10 + 1 (v/v), as mobile phase, and the analyte spots were quantified densitometrically at λ = 305 nm. Recovery of sildenafil citrate was 100.6 and 98.2%, for pure and spiked samples, respectively. Method precision and specificity were also validated. The method was used for determination of sildenafil in four pharmaceutical products and three aphrodisiac herbal preparations which were claimed to be totally natural. Levels of sildenafil in the pharmaceutical products ranged from 49.7 to 50.5 mg per tablet. Sildenafil was also detected in one herbal preparation at a concentration of 85.0 mg per capsule.

High-Speed Extraction and HPLC Fingerprinting of Medicinal Plants – II. Application to Harman Alkaloids of Genus Passiflora

Although the presence of harman alkaloids in the genus Passiflora has been established in a few species, their presence in the medicinally significant P. incarnata (passion flower) is still debatable. Powdered samples from 91 Passiflora species were subjected to accelerated speed extraction and analyzed for their content of five harman alkaloids by reversed-phase HPLC with photodiode array detection. The utilized analytical method was capable of detecting harman alkaloids in more than 50% of the analyzed samples at ppm levels. A library of HPLC chromatograms has also been generated as a tool for fingerprinting and authentication of the studied Passiflora species.