Amany K. Ibrahim

New antibacterial xanthone from the marine sponge-derived Micrococcus sp. EG45

Microluside A [4 (19-para-hydroxy benzoyloxy-O-β-D-cellobiosyl), 5 (30-para-hydroxy benzoyloxy-O-β-D-glucopyranosyl) xanthone (1)] is a unique O-glycosylated disubstituted xanthone isolated from the broth culture of Micrococcus sp. EG45 cultivated from the Red Sea sponge Spheciospongia vagabunda. The structure of microluside A was determined by 1D- and 2D-NMR techniques as well as high resolution tandem mass spectrometry. The antimicrobial activity evaluation showed that 1 exhibited antibacterial potential against Enterococcus faecalis JH212 and Staphylococcus aureus NCTC 8325 with MIC values of 10 and 13 μM, respectively.

Anti-H5N1 virus flavonoids from Capparis sinaica Veill

Methanolic extract of Capparis sinaica Veill was tested for its in vitro antiviral activity against highly pathogenic avian influenza strain H5N1 using plaque inhibition assay in Madin–Darby canine kidney. The results indicated that the extract possessed potent antiviral activity (100% inhibition at the concentration of 1 μg/ml). Based on this result, C. sinaica Veill was selected for further study by applying bioactivity-guided fractionation to isolate its antiviral principles. The fractions eluted with EtOAc and 25% MeOH in EtOAc were found to hold the antiviral activity. Further chromatographic separation of the fractions holding the antiviral activity led to the isolation of quercetin (1), isoquercetin (2) and rutin (3) for the first time from this species. The isolates showed reduction in the virus titre by 68.13%, 79.66% and 73.22% inhibition at a concentration of 1 ng/ml, respectively.

Enhancement of oleandrin production in suspension cultures of Nerium oleander by combined optimization of medium composition and substrate feeding

Abstract Oleandrin has been identified as the most potent antitumor ingredient of the Mediterranean herb Nerium oleander L. A strategy for optimization of medium compositions and conditions was developed for enhanced oleandrin production in suspension cultures from leaf-origin explants of Nerium oleander. The cell suspension cultures were grown in various modifications of MS medium as a basal medium. The effects of different natural extracts, plant growth substances, carbon and nitrogen sources and phosphate on the growth and oleandrin accumulation were investigated as well as effect of light, pH, shaking speed and substrate feeding. The highest oleandrin yield was obtained when the nitrogen concentration was lowered to two-thirds and the phosphate concentration increased by two-thirds of that specified in the MS medium in the presence of 3% sucrose, coconut milk, indolebutyric acid and benzyladenine in concentrations of 1 and 2 mg l−1, respectively. Lower pH and faster shaking speed favored oleandrin accumulation. Chemical feeding of progesterone and cholesterol boosted the oleandrin concentration to higher levels reaching 8.23±0.05 mg g−1 dry weight. This was about 10-fold higher than that detected in field-grown plants using the same extraction and analytic conditions, and about 24-fold higher than that determined in control cultures with regular MS medium and without precursor feeding.

Antichlamydial Sterol from the Red Sea Sponge Callyspongia aff. implexa

Marine sponges are rich sources of natural products exhibiting diverse biological activities. Bioactivity-guided fractionation of the Red Sea sponge Callyspongia aff. implexa led to the isolation of two new compounds, 26,27-bisnorcholest-5,16-dien-23-yn-3β,7α-diol, gelliusterol E (1) and C27-polyacetylene, callimplexen A (2), in addition to the known compound β-sitosterol (3). The structures of the isolated compounds were determined by 1D- and 2D-NMR techniques as well as high-resolution tandem mass spectrometry and by comparison to the literature. The three compounds (1-3) were tested against Chlamydia trachomatis, an obligate intracellular gram-negative bacterium, which is the leading cause of ocular and genital infections worldwide. Only gelliusterol E (1) inhibited the formation and growth of chlamydial inclusions in a dose-dependent manner with an IC50 value of 2.3 µM.

Mechanism of action of antiepileptic ceramide from Red Sea soft coral Sarcophyton auritum.

Chemical investigation of the Red Sea soft coral Sarcophyton auritum led to the isolation and structure elucidation of a new ceramide N-((2S,3R,4E,6E)-1,3-dihydroxyhenicosa-4,6-dien-2-yl)tridecanamide (1). Structure elucidation was achieved using spectroscopic techniques, including 1D and 2D NMR and HRMS. The anticonvulsant activity of the isolated ceramide was measured in vivo using the pentylenetetrazole (PTZ)-induced seizure model, where it successfully antagonized the lethality of pentylenetetrazole in mice. In addition, the isolated ceramide showed good anxiolytic activity when used in the light–dark transition box and the elevated plus maze compared to diazepam. The molecular modeling studies for the antiepileptic and antianxiety mechanism of the isolated ceramide suggested a CNS depressing activity possibly through GABA and serotonin receptors modulation. The pharmacological activity of the ceramide involved agonistic activity on GABA-A receptors but not 5HT3 receptors.

Determination of Acid and Neutral Cannabinoids in Extracts of Different Strains of Cannabis sativa Using GC-FID

Cannabis (Cannabis sativa L.) is an annual herbaceous plant that belongs to the family Cannabaceae. Trans-Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) are the two major phytocannabinoids accounting for over 40% of the cannabis plant extracts, depending on the variety. At the University of Mississippi, different strains of C. sativa, with different concentration ratios of CBD and Δ9-THC, have been tissue cultured via micropropagation and cultivated. A GC-FID method has been developed and validated for the qualitative and quantitative analysis of acid and neutral cannabinoids in C. sativa extracts. The method involves trimethyl silyl derivatization of the extracts. These cannabinoids include tetrahydrocannabivarian, CBD, cannabichromene, trans-Δ8-tetrahydrocannabinol, Δ9-THC, cannabigerol, cannabinol, cannabidiolic acid, cannabigerolic acid, and Δ9-tetrahydrocannabinolic acid-A. The concentration-response relationship of the method indicated a linear relationship between the concentration and peak area ratio with R2 > 0.999 for all 10 cannabinoids. The precision and accuracy of the method were found to be ≤ 15% and ± 5%, respectively. The limit of detection range was 0.11 - 0.19 µg/mL, and the limit of quantitation was 0.34 - 0.56 µg/mL for all 10 cannabinoids. The developed method is simple, sensitive, reproducible, and suitable for the detection and quantitation of acidic and neutral cannabinoids in different extracts of cannabis varieties. The method was applied to the analysis of these cannabinoids in different parts of the micropropagated cannabis plants (buds, leaves, roots, and stems).

Anti-choline esterase activity of ceramides from the Red Sea marine sponge Mycale euplectellioides

The isolation and structure elucidation of new phytoceramides from a methanolic extract of the Red Sea sponge Mycale euplectellioides was exclusively studied. Structure elucidation was achieved using spectroscopic techniques, including 1D and 2D NMR and HRMS. The anti-choline esterase activity of the isolated ceramides was evaluated in vitro using a microplate-based Ellman’s assay. Bioassay guided isolation led to the isolation of a MEC-1 phytoceramide molecular species; further purification of MEC-1 afforded three pure phytoceramides: MEC-1-4, MEC-1-7 and MEC-1-8. Molecular modeling studies using glide docking showed tight binding of the ceramides to acetylcholine esterase (AChE). The ceramides showed a better docking score and glide Emodel value when compared to known AChE inhibitors. The ceramides interacted with an aromatic residue of the peripheral anionic site and penetrated deeply into the catalytic triad residues of the active site. Overall, the ceramides obtained using the approaches described here could be considered as promising lead compounds for the discovery and design of potent anti-choline esterase drug candidates, which would be used for Alzheimer’s eradication.

Anti-H5N1 virus new diglyceride ester from the Red Sea grass Thallasodendron ciliatum

Some Egyptian plants were screened against highly pathogenic avian influenza strain H5N1 using plaque inhibition assay in Madin–Darby canine kidney. The results indicated that the extracts of Red Sea grass Thallasodendron ciliatum possessed potent antiviral activity (100% inhibition at the concentration of 1 μg mL− 1). The bioactivity-guided fractionations led to the isolation of a new diglyceride ester (1) along with asebotin (2) for the first time from the plant. The two isolates showed reduction of virus titre by 67.26% and 53.81% inhibition at concentration of 1 ng mL− 1, respectively.

New terpenoids from Mentha pulegium L. and their antimicrobial activity

In addition to one previously reported compound: two new terpenoidal compounds 1α, 6βdimethyl-5β-hydroxy-4β-(prop-1-en-2-yl)-decahydronaphthalen-2-one (1) and 1-(O-β-D-glucopyranosyl)-2,7-dimethyloct-5-en-3-one (2) were isolated from the chloroformic extract of Mentha pulegium L. The structure elucidation of these compounds was based primarily on 1D and 2D-nuclear magnetic resonance analyses. Compound 1 displayed moderate anti-MRSa (IC50 8.5 µg mL−1).

Efficient Callus Induction, Plant Regeneration and Estragole Estimation in Tarragon (Artemisia dracunculus L.).

Abstract Our research studied the fast-breeding technology of Artemisia dracunculus using tissue culture in order to provide the scientific foundation for industry production. The susceptibility of callus formation and plant regeneration was studied under different conditions of basic medium, hormones and additives. The use of explants of different origins as the leaf, stem and root explants was also studied for best callus induction rate, regeneration ability and estragole concentration. The best culture medium for the induction of calli was MS + 2.4.D 1.0 mgl−1, which started with the leaves as explants, and the best medium for stem regeneration was MS + BA 0.5 mgl−1+ NAA 0.1 mgl−1. A new HPLC method was developed to provide a specific procedure for the rapid and facile analysis of the major constituent of tarragon volatile oil estragole. Estragole concentration was estimated at all the experiment treatments including the induced calli under different medium conditions, as well as the regenerated plants. Estragole concentration was found to be 9.8% dry weight in the in vitro regenerated plantlets. Using this method estragole was found to be absent in different plant extracts of the field grown plants (acclimatized after in vitro regeneration)