Nawal M. Al Musayeib

In vitro antiprotozoal activity of triterpenoid constituents of Kleinia odora growing in Saudi Arabia.

Two lupane and four ursane triterpenes, namely epilupeol (1), lupeol acetate (2), ursolic acid (3), brein (4), 3β 11α-dihydroxy urs-12-ene (5) and ursolic acid lactone (6) were isolated from aerial parts of Kleinia odora and identified. Compounds 1 and 3–6 were isolated for the first time from K. odora. The triterpene constituents were investigated for antiprotozoal potential against erythrocytic schizonts of Plasmodium falciparum, intracellular amastigotes of Leishmania infantum and Trypanosoma cruzi and free trypomastigotes of T. brucei. Cytotoxicity was determined against MRC-5 fibroblasts to assess selectivity. The ursane triterpenes were found to be active against more than one type of the tested parasites, with the exception of compound 6. This is also the first report on the occurrence of ursane type triterpenes in the genus Kleinia and their antiprotozoal potential against P. falciparum, L. infantum, T. cruzi, and T. brucei.

Fusaripeptide A: new antifungal and anti-malarial cyclodepsipeptide from the endophytic fungus Fusarium sp.

Abstract From the culture of the endophytic fungus Fusarium sp. isolated from the roots of Mentha longifolia L. (Labiatae) growing in Saudi Arabia, a new cyclodepsipeptide, namely fusaripeptide A (1), along with three known compounds adenosine (2), 2[(2-hydroxypropionyl)amino]benzamide (3), and cyclopentanol (4), have been isolated. Their structures were determined, using extensive 1D and 2D NMR and HRESI and GC mass spectral data. That is the first report for the isolation of compound 4 from natural source. In addition, compounds 2 and 3 are reported here for the first time from Fusarium sp. The absolute configuration of the amino acid residues of 1 was assigned by chiral GCMS and Marfey’s analysis after acid hydrolysis. Fusaripeptide A differs from the reported ones from Fusarium sp. in the length of fatty acidic alkyl chain. Compound 1 was evaluated for its antifungal, anti-malarial, and cytotoxic activities. It exhibited potent antifungal activity toward C. albicans, C. glabrata, C. krusei, and A. fumigates with IC50 values of 0.11, 0.24, 0.19, and 0.14 μM, respectively. Furthermore, it had significant anti-malarial activity toward P. falciparum (D6 clone) with IC50 value of 0.34 μM. However, it showed cytotoxic activity toward the tested cell lines.

Elucidation of the interaction of human serum albumin with anti-cancer sipholane triterpenoid from the Red Sea sponge.

A sipholane triterpenoid, named sipholenone A, with anti-cancer properties was isolated from the Red Sea sponge Siphonochalina siphonella and characterized by proton and carbon-13 nuclear magnetic resonance (1 H NMR and 13 C NMR) spectroscopies. The goal of this study was to visualize the binding of this triterpenoid with human serum albumin (HSA) and to determine its binding site on the biomacromolecule. The interaction was visualized using fluorescence quenching, synchronous fluorescence, far- and near-UV circular dichroism (CD), UV-visible and Fourier transform-infrared (FT-IR) spectroscopies. UV-visible spectroscopy indicated the formation of a ground-state complex as a result of the interaction. Sipholenone A quenches the fluorescence of HSA via a static quenching mechanism. A small blue shift in the fluorescence quenching profiles suggested the involvement of hydrophobic forces in the interaction. Sipholenone A binding takes place at site I of subdomain II A with a 1:1 binding ratio, as revealed by displacement binding studies using warfarin, ibuprofen and digitoxin. Far-UV CD and FT-IR studies showed that the binding of sipholenone A to HSA also had a small effect on the proteins secondary structure with a slight decrease in the α-helical content. Several thermodynamic parameters were calculated, along with Forsters radiative energy transfer analysis.

Klodorone A and klodorol A: new triterpenes from Kleinia odora

Re-investigation of the EtOH extract of the aerial parts of Kleinia odora led to the isolation of two new triterpenes; klodorone A (3) and klodorol A (4), together with two known compounds: β-amyrin (1) and germanicol (2), which were reported from this plant for the first time. Their structures were determined by using extensive 1D (1H, 13C and DEPT) and 2D (1H–1H COSY, HMQC and HMBC) NMR and mass spectral measurements in addition to comparison of their data with the literature.

Low temperature synthesis of Manganese tungstate nanoflowers with antibacterial potential: Future material for water purification

Pure water is the fundamental requisite for human life. The water has been recycled naturally but not in an adequate amount for consumption. Nanotechnology with extraordinary applications provides competent ways for the decontamination of contaminated water. In the present study MnWO4 nanoflowers endorsed with inherent antibacterial activity were successfully synthesized by facile hydrothermal approach. XRD, SEM, EDX spectroscopy and UVDRS were used to characterize the as-synthesized nanoflowers. Gram negative Escherichia coli ATCC 52922 bacterium was used as model organism to test antibacterial activity of as-synthesized MnWO4 nanoflowers. This study was conducted to optimize minimum concentration of MnWO4 nanoflowers and maximum contact time required to achieve complete inactivation of bacteria present in contaminated water. Minimum inhibitory concentration (MIC) of MnWO4 nanoflowers was found to be 10 μg/ml. The assessment and interpretation of bacterial viability was done using dual fluorescent staining. The synthesized 3D-nanoflowers were found as potent bactericides. Thus, MnWO4 nanoflowers emerged to be very good future material for disinfection of biological pollutants present in the contaminated water reservoirs and as an anti-biofouling agent.

Curviflorside and curviflorin, new naphthalene glycoside and flavanol from Plicosepalus curviflorus

Abstract The naphthalene glycosidecurviflorside [1,5-dihydroxy-8-methoxynaphthalene-2-O-β-D-xylopyranoside] (3) and the flavanol curviflorin [(+)-catechin-7-O-3″,4″-dihydroxybenzoate] (4), along with two known flavonoids: (+)-catechin (1) and quercetin (2) were isolated from the shoots of Plicosepalu scurviflorus Benth. (Loranthaceae) growing in Saudi Arabia and the chemical structures were elucidated by 2D-NMR spectroscopy.