Volume 69, Issue 1-2

Thirteen selected Saudi Arabian plants, belonging to seven different families, were tested for possible anti-inflammatory activity using the carrageenin-induced paw edema model in rats. The methanolic extracts of Vernonia schimperi, Trichodesma trichodesmoides var. tomentosum, and Anabasis articulata exhibited the highest anti-inflammatory activity. The active extracts were further subjected to fractionation with chloroform, ethyl acetate, and n-butanol and tested together with their mother liquor for their anti-inflammatory activity in the same rat model. The most potent fractions were the n-butanol fractions of Anabasis articulata and Vernonia shimperi and the aqueous mother liquor of Trichodesma trichodesmoides. Nevertheless, the three potent methanolic extracts showed higher anti-inflammatory activities than their individual fractions. The antioxidant properties were assessed by their in vitro 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical scavenging activities. It was concluded that the anti-inflammatory activity is dependent, at least in part, on the reduction of prostaglandin (PGE 2 ) and tumour necrosis factor-α (TNF-α) levels and cyclooxygenase-2 (COX-2) activity.

Propolis is a beehive product that bees manufacture by mixing their own wax with vegetable resins collected from different species of trees and bushes. The chemical composition of propolis is very variable because it depends on the flora locally available, and specimens from different geographical and climatic areas display unique properties. In this paper, the results of the chemical characterization of some propolis specimens collected in northern California and in Oregon are presented. Their chemical compositions show that all specimens contain resins from poplars of the Tacamahaca section (balsam poplars) - characteristic of the western part of the North American continent. Nevertheless, some of the specimens are of mixed origin because they also contain resins from poplars of the Aigeiros section (cottonwoods) - also present in this part of the world. Propolis causes allergies in sensitive human individuals, which are due to the presence of certain esters. The contents of known propolis allergenic esters - phenylethyl caffeate, 1,1-dimethylallyl caffeate, benzyl cinnamate, and benzyl salicylate - have been investigated in these specimens and found to depend on the botanical origin.

Five novel derivatives of N-(9,10-dihydro-9,10-dioxoanthracenyl)-1H-indole-2-carboxamide were synthesized and their lipid-lowering effects studied in hyperlipidemic rats. Fusion of the anthraquinone derivatives at high temperature with 5-indole-2-carbonyl chloride, followed by recrystallization from chloroform=methanol gave the desired compounds in excellent yields. Compounds 1 to 5 at a non-toxic dose (1 ml of 57 mM solutions) and bezafibrate as positive control were administered to rats that were hyperlipidemic due to treatment with Triton WR-1339. A decrease in the plasma levels of triglyceride (TG) and low-density lipoprotein-cholesterol (LDL-C) and an increase in the plasma level of high-density lipoprotein-cholesterol (HDL-C) were observed with compounds 1, 3, 4, and 5. Compounds 1, 4, and 5 significantly reduced total cholesterol (TC) levels as well. These compounds may provide agents for targeting dyslipidemia and cardiovascular disease.

Vismia mexicana (Clusiaceae) is a small tropical tree found from Mexico to Honduras. The CH 2 Cl 2 =MeOH extract from the leaves has been reported to have inhibitory properties against reverse transcriptase of human immunodeficiency virus type 1 (HIV-1 RT). In order to characterize some of its chemical constituents, the EtOAc-soluble fraction of this extract was subjected to column chromatography. A new natural product was isolated and designated vismiaquinone D [1-hydroxy-6- methoxy-7,8-(3',3'-dimethyl-pyrano) anthraquinone]. In addition, vismiaquinone was obtained. The structures of vismiaquinone and vismiaquinone D were determined by 1 H and 13 C NMR spectroscopy, unambiguous assignments were achieved with DEPT, HSQC, and HMBC experiments, and corroborated by X-ray diffraction studies. The isolated anthraquinones were tested against HIV-1 RT. However, none showed relevant activity, suggesting that other compounds in this extract may be responsible for its HIV-1 RT inhibitory properties.

The effect of an aqueous Mentha cordifolia (MC) extract on the haemodynamic status, vascular remodeling, function, and oxidative status in N G -nitro-L-arginine methyl ester (L-NAME)-induced hypertension was investigated. Male Sprague-Dawley rats were given L-NAME [50 mg/(kg body weight (BW) d)] in their drinking water for 5 weeks and were treated by intragastric administration with the MC extract [200 mg/(kgBWd)] for 2 consecutive weeks. Quercetin [25 mg/(kg BW d)] was used as a positive control. The effects of the MC extract on the haemodynamic status, thoracic aortic wall thickness, and oxidative stress markers were determined, and the vasorelaxant activity of the MC extract was tested in isolated mesenteric vascular beds in rats. Significant increases in the mean arterial pressure (MAP), heart rate (HR), hind limb vascular resistance (HVR), wall thickness, and cross-sectional area of the thoracic aorta, as well as oxidative stress markers were found in the LNAME- treated group compared to the control (P<0.05). MAP, HVR, wall thickness, cross-sectional area of the thoracic aorta, plasma malondialdehyde (MDA), and vascular superoxide anion production were significantly reduced in L-NAME hypersensitive rats treated with the MC extract or quercetin. Furthermore, the MC extract induced vasorelaxation in the pre-constricted mesenteric vascular bed with intact and denuded endothelium of normotensive and hypertensive rats. Our results suggest that the MC extract exhibits an antihypertensive effect via its antioxidant capacity, vasodilator property, and reduced vascular remodeling.

The Orchidaceae family is appreciated worldwide for the beauty of its flowers, and hundreds of species of this family occur in Brazil. Yet little is known about the potential of orchids for therapeutic application. We have investigated bioactive compounds produced by the South Brazilian orchid Miltonia flavescens Lindl. Bioguided studies with the fungus Cladosporium herbarum allowed the identification of hydrocinnamic acid as the active antifungal compound. In addition, the chloroform fraction exhibited an interesting activity against human cancer cells, and 5,7-dihydroxy-6,4'- dimethoxyflavone isolated from this fraction was found to be active against seven human cancer cell lines, including NCI/ADR-RES ovary sarcoma, with an IC 50 value of 2.6 mg/mL. This is the first report on the cytostatic activity of this flavone against human ovary sarcoma.

Microcystis and Anabaena are the main cyanobacteria that cause cyanobacterial blooms in Taihu Lake, China. The mechanism of population competition between M. aeruginosa and A. flos-aquae was studied by co-cultivation in the laboratory. The growth of M. aeruginosa was inhibited, while the growth of A. flos-aquae was promoted. The degree of inhibition or promotion was related to the ratio of the initial cell densities. Both cell-free filtrates of A. flos-aquae and co-culture inhibited M. aeruginosa growth, while both cell-free filtrates of M. aeruginosa and co-culture promoted A. flos-aquae growth. Analysis of the cell-free filtrate by gas chromatography-mass spectrometry indicated that M. aeruginosa and A. flos-aquae may secrete some extracellular allelochemicals that inhibit (promote) the growth of M. aeruginosa (A. flos-aquae) in co-culture. These compounds included sulfur compounds, naphthalene derivatives, cedrene derivatives, quinones, phenol derivatives, diphenyl derivatives, anthracene derivatives, and phthalate esters. This study can help to understand the characteristics of M. aeruginosa and A. flos-aquae and to provide new concepts for the control of cyanobacterial blooms in Taihu Lake.

The influence of the cultivation system and of the culture medium on the biotransformation of (+)-limonene by a strain of Aspergillus niger was investigated. Biooxidation products were obtained in all conditions tested. Using a laboratory bioreactor, six terpenes were identified in every medium, predominantly terpineols and carveols, whereas terpinen-4-ol and perillyl alcohol were the only terpenes found when flasks were used for culture. Perillyl alcohol and carveols predominated when the medium was tryptic soy broth (TSB), whereas the formation of terpineols was clearly favoured in malt broth (MB). Thus, there was a marked influence of the culture conditions on the results of the biotransformation. Changes in the conditions led to variations both in the type and relative amount of products obtained.

Our previous data demonstrated that CoCl 2 -induced hypoxia controls endoplasmic reticulum (ER) stress-associated and other intracellular factors. One of them, the transcription factor Pokemon, was differentially regulated by low-dose radiation (LDR). There are limited data regarding how this transcription factor is involved in expression of the unfolded protein response (UPR) under hypoxic conditions. The purpose of this study was to obtain clues on how Pokemon is involved in the UPR. Pokemon was selected as a differentially expressed gene under hypoxic conditions; however, its regulation was clearly repressed by LDR. It was also demonstrated that both expression of ER chaperones and ER stress sensors were affected by hypoxic conditions, and the same results were obtained when cells in which Pokemon was up- or down-regulated were used. The current state of UPR and LDR research associated with the Pokemon pathway offers an important opportunity to understand the oncogenesis, senescence, and differentiation of cells, as well as to facilitate introduction of new therapeutic radiopharmaceuticals

Biotechnology of microalgae represents a very attractive alternative as a source of energy and substances of high value when compared with plant cultivation. Cell walls of green microalgae have an extraordinary chemical and mechanical resistance and may impede some steps in the biotechnological/industrial exploitation of algae. The aim of the present contribution was to check the presence of polyamines in the cell walls of chlorococcalean green microalgae. Polyamines are nitrogenous compounds synthesized normally in cells and may affect the properties of the cell wall. Our work included strains either forming or not forming the polymer algaenan, allowing us to conclude that algaenan is not a prerequisite for the presence of polyamines in the cell walls. Polyamines were detected in isolated cell walls of Scenedesmus obliquus, Chlorella fusca, Chlorella saccharophila, and Chlorella vulgaris. Their concentration in isolated cell walls ranged between 0.4 and 8.4 nmol/mg dry weight.

Base excision repair (BER) is a key pathway for maintaining genomic stability. A key enzyme in the BER pathway is DNA polymerase beta (polβ). It has been shown that more than 11% of breast, bladder, esophageal, colon, and gastric cancer samples studied so far exhibit polβ mutation. A truncated form of polβ, polβΔ (exon 11 deletion), identified in a colon tumour sample, exhibited dominant negative activity. Using this poβΔ as bait, we screened a HeLa cDNA library for any interacting protein(s) in the yeast two-hybrid (Y2H) system. PolβΔ was cloned into a pGBKT7 vector (pGBKT7-polβΔ). pGBKT7-polβΔ was transformed into the yeast strain AH109. Then the cDNA library was co-transformed into AH109=pGBKT7-polβΔ and screened by the selection procedure. The yeast-purified plasmids were transformed into Escherichia coli. Plasmid DNA was isolated from the colonies, purified, digested with Sma I and Sal I, and the fragments were sequenced. Four positive clones were obtained. Out of these, three proteins were already known to interact with polβ (XRCC1, MGC5306, and AP endonuclease 1). The only member previously not known to interact with polβ was phosphatidylinositol glycosylase type S (PIGS). PIGS is a 64-kDa membrane protein, encoded in chromosome 17. The PIGS protein interacts also with wild-type polβwhich was confirmed by co-immunoprecipitation and Western blot analysis. The role of the newly identified protein in the dominant negative function of the variant form of polβ remains to be seen.