The antioxidant properties of the natural plant extracts can be resulted from their ability to chelate transition metal ions, especially Fe 2+ and Cu 2+. For example, the complex formation between ferrozine and Fe 2+ can be disturbed by the presence of other complexing agents which cause a decrease in the red colour intensity of complexes. Phenolic compounds from Pandanus extracts (family: Pandanaceae) may consist of dihydroxy groups, which can conjugate transition metals, therefore preventing the metal-induced free radical formation. This study investigates the metal chelating capacity of Pandanus pygmaeus extracts and their column chromatographic fractions. The ferrous ion chelating (FIC) assay was performed to determine the ability of the extracts in chelating ferrous ion. The stock solution was diluted to five concentrations (1-10 000 µg/mL). 500 µL samples at different concentrations were mixed with 100 µL of 0.6 mM ferrous chloride (FeCl 2 ) and 900 µL of methanol (MeOH). Then, the mixtures (1.50 mL) were incubated for 5 minutes at room temperature. Next, 100 µL of 5 mM ferrozine was added, mixed thoroughly and left in the dark for another 10 minutes. The absorbance of the solution was measured spectrophotometrically at 562 nm. The respective solvent used in this bioassay served as a blank control. Ethylene diamine tetraacetate (EDTA) was used as positive control. The percentage inhibition of ferrozine-Fe +2 formations was calculated. In this assay, only the MeOH extract of P. pygmaeus and positive control EDTA exhibited the chelating activity. The absorbance of ferrous and ferrozine complex was decreased dose-dependently, which means that the chelating activity was increased on increasing concentration from 1-10 000 µg/mL. The highest chelating activity of MeOH extract and EDTA is at 10 000 µg/mL with 85.39% and 99.81%, respectively. However, the chelating activity of MeOH extract still can be improved by increasing the concentration. However, compared to positive control of EDTA, IC 50 of MeOH extract was higher than that of EDTA. The smaller the IC 50 value, the higher the metal chelating activity of the compound / extract. This reveals that the MeOH extract is a moderate metal chelating agent as compared to EDTA. On the other hand, the hexane and dichloromethane extracts do not show any chelating activity as IC 50 value could not be determined. The ferrous ion-chelating activity was shown by methanolic extract of P. pygmaeus and positive control EDTA with IC 50 values 2256.50 ± 59.53 µg/mL and 18.35 ± 0.99 and µg/mL, respectively.
The occurrence of alkaloids in Pandanaceae family was studied, due to their structural distinctiveness. Within the Pandanus genus, the alkaloidal components were investigated from P. amaryllifolius (the scented screwpines), followed by P. dubius (locally known as mengkuang). Pandanus' aromatic compound is attributed to a simple alkaloid, 2-acetyl-1-pyrroline. To date, twenty two alkaloids were reported from the above species, out of 600 Pandanus plants. From the review, it is anticipated that a specific Pandanus would contain a particular alkaloidal skeleton. The carbon arrangement might be constructed owing to the enzymatic cyclisation of the biogenetic precursor, Pandanamine. Hence, it is factual that Pygmauesamine, which possess an indolizidine, is a new alkaloid from P. pygmaeus. However, following a repetitive extraction of the leaves, another molecule could be purified. Based on the spectroscopic data, it is aimed that an isomer of Pygmauesamine could be recognized. The methodology includes the gravitational silica column and centrifugal radial thin layer chromatography of the dichloromethane extract. Nuclear magnetic resonance (NMR) spectroscopy (500 MHz, CDCl 3 , δ H 0 -8 ppm) was used to identify the molecular structures. The findings include the isolation of one alkaloid. An orange spot was observed when the silica plate was sprayed with the Dragendorff reagent. Spectroscopic evidences suggested that the protons' chemical shifts of this molecule are assortment of signals from Pandanamine (an alkaloid from P. amaryllifolius) and Dubiusamine A (a biologically active alkaloid from P. dubius). The presence of additional protons in the structure might give a molecular formula of C 18 H 27 NO 4 . Consequently, an isomeric Pygmaeusamine, arbitrarily labeled as Pygmaeusamine B, was proposed as another alkaloid from P. pygmaeus. The NMR spectral elucidation of this compound could suggest that it is a novel Pandanus alkaloid. Subsequent assessments will also feature the protons' spatial interaction in Pygmaeusamine B and the confirmation of the mass data.
This is a brief introduction of a phytochemical work involving the small screwpines, Pandanus pygmaeus (family: Pandanaceae). The objective is to purify the natural products from the extracts. Previous work discussed other Pandanus, such as P. boninensis, P. sanderi, and not overlooking the fragrant screwpines, P. amaryllifolius. Research papers also published the structures of Pandanus' constituents; particularly the triterpenes. From the literature review, these molecules are the steroidal precursors of the plant hormone and possess biological properties, comparable to the antimicrobial compounds. In an earlier experiment, only one colourless triterpene from the hexane fraction was gained. This compound was later established as stigmasterol, after the crystallization and spectroscopic assessments. Therefore, a quadrupled amount of P. pygmaeus was extracted, in order to study other triterpenoids from this species. The adopted methodology consisted of normal silica column chromatography, accompanied with both analytical and preparative thin layer chromatography of the hexane crude extract. The fractionation procedure was planned according to the nonpolarity of each organic component. Nuclear magnetic resonance spectroscopy (500 MHz, CDCl 3 ) was used to identify the molecular structures. The main findings include the isolation of two possible triterpenes. Blue spots were visualised when vanillin was utilised as the spray reagent. Preliminary spectroscopic evidences suggested that the carbon arrangement of the molecules belong to other than the stigmasterol. On the other hand, the presence of an olefinic system might include a vinyl proton, directly attached to the carbon-carbon double bond. Nevertheless, this fragment is unlike the one from the antitubercular triterpene of P. sanderi, where an exomethylene moiety was instead characterised. The purification of these triterpenes should be highlighted, since this is the second report of such occurrence from P. pygmaeus. Ongoing work also incorporates the antibacterial and antifungal evaluation of these compounds.
Garcinia atroviridis fruit has been shown to express anti-obesity activity as a result of its bioactive compound, hydroxycitric acid (HCA). HCA is effective in decreasing appetite, inhibiting fat synthesis, and reducing body weight. However, HCA is very unstable towards certain conditions thus limiting its bioavailability. To overcome the issue of HCA instability, HCA was encapsulated in chitosan (CS) nanoparticles in this study. CS nanoparticles were prepared based on ionic gelation using sodium tripolyphosphate (TPP) as a cross-linking agent. The concentration of chitosan and TPP: chitosan volume ratios were varied and the resulting nanoparticles were characterized based on zeta potential, particle size, encapsulation efficiency (EE%), and kinetics release. The most optimum nanoparticle was obtained with a combination of 1.5 mg/mL chitosan with a CS: TPP volume ratio of 4: 1. Zeta potential was measured by approximately 49 mV. The size of the particle at optimum condition was found to be 140 nm and the nanoparticle had high encapsulation efficiency (87.55±5.35%). G. atroviridis extract release from CS nanoparticles followed either Higuchi or Korsmeyer Peppas kinetic model. FT-IR studies indicated that G. atroviridis was encapsulated in CS nanoparticles. The present study revealed that concentration of chitosan, and CS: TPP volume ratio can significantly change the physical characteristics of the nanoparticles and this provides an avenue for formulators to engineer CS nanoparticles according to needs.
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