Contamination levels of toxic metals in selected traditional plants incense (gum).

Gums are polysaccharides, proteins, and minerals that occur naturally in seed coverings and as exudative resinous substance from woody plants. It is reported to have antibacterial, anticancer, blood sugar regulation, and immune system boosting properties. However, the presence of toxic metals in gum is caused for caution as these metals can be harmful if taken in high quantities. The purpose of this study was to determine the amounts of toxic metals in gums collected from the local market, as many consumers tend to use them daily for incense or food ingredients. Gum samples were extracted from several parts of 10 selected medicinal plants (bark, sap, root, latex, leaf glue, and gum). Two fractions of each sample were produced using nitric acid (NHO3), followed by hydrochloric acid (HCl) at first and then hydrogen peroxide (H2O2). The presence of toxic metals in the solutions was determined using an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP OES). The results showed that most of the elements were detected in high concentrations in Commiphora myrrha (Cd, Cu, Fe, K, Mn, Ni, Pb, and Zn) followed by Benzoin resin (Jawi Oud) and Paeonia officinalis. The most prevalent elements detected in all of the herbal gums were potassium (K) and iron (Fe). Fortunately, the sampled herbal gums were found to be within the WHO/FAO permitted range. This study may provide insights about the safety of the selected gums to be used for food applications. Further in vitro and in vivo toxicity studies should be performed to identify the safe dose.

[Determination of phenolic compounds in Chinese poplar propolis, Brazil green propolis, and poplar gum by high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry and preliminary study of the identification of adulteration].

High-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (HPLC/Q-TOF MS) was used to analyze 23 phenolic compounds in Chinese poplar propolis, Brazil green propolis, and poplar gum. Propolis and poplar gum samples were dissolved in methanol-water (1:1, v/v) and filtered by 0.45 µm organic phase filtration membrane. The separation was carried out in an Agilent Eclipse Plus C18 column with gradient elution using acetoni-trile and 0.1% (volume percentage) formic acid solution as the mobile phases. The compounds were detected using positive ion electrospray ionization in full scan mode (m/z 100-1000). The quantification analysis was performed by the external standard method. The results showed that all the compounds were linear, with correlation coefficients>0.99, in the range of 10-20 µg/L. The limits of detection and limits of quantification for tangeretin and formononetin were 0.2 and 1 µg/L, respectively, and those for the other compounds were 2 and 10 µg/L, respectively. At the spiked levels of 10, 25, and 50 mg/kg, the recoveries of all the compounds ranged from 70.2% to 122.6%, with relative standard deviations of less than 10%. Salicin, cinnamic acid, caffeic acid, and coumaric acid could be used as markers for detecting adulteration in Chinese poplar propolis, while caffeic acid, ferulic acid, chrysin, caffeic acid phenethyl ester, pinocembrin, galangin, coumaric acid, isorhamnetin, kaempferide, and arte-pillin C could be used as markers for identifying Chinese poplar propolis and Brazil green propolis. The results presented in this paper may be helpful in quality control of propolis products.

Structural characterization of mesquite (Prosopis velutina) gum and its fractions.

Structural and physicochemical characteristics of mesquite gum (from Prosopis velutina) were investigated using FT-IR spectroscopic, mass spectrometric and chromatographic methods. Four fractions (F-I, F-IIa, F-IIb and F-III) were isolated by hydrophobic interaction chromatography. The samples were characterized and analyzed for their monosaccharide and oligomers composition by high performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD). L-Arabinose (L-Ara) and D-galactose (D-Gal) were found as the main carbohydrate constituent residues in the polysaccharides from mesquite gum and their ratio (L-Ara/D-Gal) varied within the range 2.54 to 3.06 among the various fractions. Small amounts of D-glucose (D-Glc), D-mannose (D-Man) and D-xylose (D-Xyl) were also detected, particularly in Fractions IIa, IIb and III. Infrared spectroscopy identified polysaccharides and protein in all the samples. Data from mass spectrometry (MALDI-TOF MS) was consistent with the idea that the structure corresponding to the periphereal chains of Fraction I is predominantly a chain of pentoses attached to uronic acid.

Purification of guar gum for biological applications.

Commercial guar gum (GG) was purified by four different methods and characterized by gel permeation chromatography (GPC), thermogravimetric analysis and the determination of monosaccharides composition, protein and copper content, turbidity, intrinsic viscosity and rheological parameters. The first method was based on enzymatic hydrolysis with porcine pancreatin. In the second method successive gum dissolution, centrifugation and precipitation with acetone and ethanol were carried out. Precipitation with Fehling solution was employed in the third method. In the fourth method, the gum was purified by method 2 and then by method 3. All methods led to a reduction in protein content, arabinose and glucose residues, considered as sugar contaminants, and also in intrinsic viscosity and molar mass. Total elimination of protein was only achieved by method 4. Using methods 3 and 4, the gum was contaminated with small amounts of Cu(II) from the Fehling solution. Methods 2 and 4 apparently provided purer guar gum. If the amount of protein is a crucial parameter in the biological application and the guar will be taken in low amounts, method 4 is recommended. Taking into account the purity, thermal stability, rheological parameters of the purified gum and also the cost and simplicity of the procedure, method 2 has wider biological application.