Phytochemical content and antioxidant properties of Bornean wild durian from Sabah

Borneo is the centre of diversity of the genus Durio (family: Malvaceae; local name: durian). Durian fruit is known to contain high amounts of the major bioactive compounds (as antioxidants) such as anthocyanins, carotenoids, polyphenols and flavonoids. Two types of wild durian species, namely Durio kinabaluensis Kosterm. & Soegeng (durian tupoloh) and Durio oxleyanus Griff. (durian sukang) were studied. The 80% methanolic extracts of flesh, seed and peel (mesocarp and exocarp) were analysed for antioxidant activities, total phenolic and total flavonoid content. The antioxidant activities were determined using three parameters; 2,2-diphenyl-1-picrylhydrazyl radical assay (DPPH), 2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical cation assay, and Ferric reducing antioxidant power assay (FRAP). Durio kinabaluensis mesocarp extract displayed the highest antioxidant properties and total phenolic content. The non-edible parts of both durians (seed and peel) exhibited higher phytochemical contents and antioxidant properties compared to the flesh parts. This data may contribute to the pharmaceutical applications, health benefit information of wild durians and helps in popularising the potential of these fruits in international markets and ultimately protects them from extinction

Characterization of biofilms developed from alginate extracted from Padina sp. incorporated with calcium chloride (CaCl2)

Seaweed has been used in many industries, whether directly or its extract. Padina sp. is one of the understudied species of brown seaweed. Brown seaweed have alginate embedded in their cell wall which is a type of hydrocolloids and can be used in many industries and applications including development of biofilms. The main objective of this current study is to develop biofilms using alginate extracted from Padina sp. and incorporated with calcium chloride at different concentrations. Prior to that, the functional groups of Padina sp. and alginate extract were determined. Then, functional groups, surface morphology, mechanical properties, swelling ability and biodegradability of the biofilms were studied using standard methods. The results showed that there were no significant changes in their FTIR spectra with increasing CaCl2 content. Surface morphology showed improvement in bonding while mechanical properties showed the best tensile strength of 9.43mm and 8.61mm elongation-at-break (EAB) after addition of 0.12g CaCl2. As for their swelling and biodegradability, the samples were completely dissolved after one hour and degraded after 24 hours. This shows that the biofilms with CaCl2 indeed improve the quality of alginate-based biofilms which can further be studied to improve other aspects such as water sorption kinetic and thermal stability

Characterization of CdSe nanocrystals coated with amphiphiles. A capillary electrophoresis study

We have synthesized CdSe nanocrystals (NCs) possessing a trioctylphosphine surface passivation layer and modified with amphiphilic molecules to form a surface bilayer. The NCs covered with single amphiphiles are not stable in aqueous solution, but a mixed amphiphilic system is shown to provide stability in solution over several months. The solutions of the modified NCs were characterized by UV-Vis absorbance, photoluminescence, and transmission electron microscopy. An electrophoretic study revealed two operational modes. The first relies on the enrichment of NCs using a micellar plug as a tool. The accumulation of NCs at the plug-electrolyte buffer interface results in a sharp peak. By controlling the electrophoretic conditions, nanocrystals were forced to exit a micellar plug into an electrolyte buffer. We conclude that a system consisting of modified nanocrystals and a micellar plug can act as a mixed pseudomicellar system, where modified nanocrystals play the role of pseudomicelles

Capillary electrophoretic separation of nanoparticles

In the present work, CdSe nanocrystals (NCs) synthesized with a trioctylphosphine surface passivation layer were modified using amphiphilic molecules to form a surface bilayer capable of providing stable NCs aqueous solutions. Such modified nanocrystals were used as a test solute in order to analyze new electrophoretic phenomena, by applying a micellar plug as a separation tool for discriminating nanocrystals between micellar and micelle-free zones during electrophoresis. The distribution of NCs between both zones depended on the affinity of nanocrystals towards the micellar zone, and this relies on the kind of surface ligands attached to the NCs, as well as electrophoretic conditions applied. In this case, the NCs that migrated within a micellar zone can be focused using a preconcentration mechanism. By modifying electrophoretic conditions, NCs were forced to migrate outside the micellar zone in the form of a typical CZE peak. In this situation, a two-order difference in separation efficiencies, in terms of theoretical plates, was observed between focused NCs (N ~ 107) and a typical CZE peak for NCs (N ~ 105). By applying the amino-functionalized NCs the preconcentration of NCs, using a micellar plug, was examined, with the conclusion that preconcentration efficiency, in terms of the enhancement factor for peak height (SEFheight) can be, at least 20. The distribution effect was applied to separate CdSe/ZnS NCs encapsulated in silica, as well as surface-modified with DNA, which allows the estimation of the yield of conjugation of biologically active molecules to a particle surface

Effects of ascorbic acid and ferum ions concentration on the hydrolysis of glucosinolate and myrosinase activity in the watercress (Nasturtium officinale sp.)

Watercress (Nasturtium officinale sp.) from the Brassicae family contains phenethyl glucosinolates (gluconasturtiin) as the main glucosinolate (GLS). The enzymatic hydrolysis products by naturally-occuring myrosinase produced phenethyl isothicyanate (PEITC) which reported to possess anti-carcinogenic activity. Depending on several factors, its counterpart, phenethyl nitrile (PEN) can also be formed as hydrolysis product. This study investigated the effects of adding ascorbic acid and Fe2+ ions at different concentration on the hydrolysis of gluconasturtiin. Hydrolysis products were extracted using dichloromethane and analyzed semi-quantitatively by using GCMS. The results showed that PEITC increased at the low concentration of ascorbic acid (up to 0.06M). Similarly, addition of up to 0.06M Fe2+ ions increased PEITC; higher than 0.06M inhibits the formation of PEITC. Interestingly, similar trend for the production of PEN was detected. This study also investigated myrosinase activity both by exogenous and endogenous methods at different concentrations of ascorbic acid and Fe2+ ions using standard sinigrin as subsrat. Overall, the myrosinase activity was more active at the low concentrations of ascorbic acid. Also, the exogenous method is more efficient than endogenous. This study proved that the presence of reducing agents such as ascorbic acid and Fe2+ ions during the preparation of watercress as food would affect the production of the health-promoting PEITC

Phytochemical content and antioxidant properties of Bornean wild durian from Sabah

Borneo is the centre of diversity of the genus Durio (family: Malvaceae; local name: durian). Durian fruit is known to contain high amounts of the major bioactive compounds (as antioxidants) such as anthocyanins, carotenoids, polyphenols and flavonoids. Two types of wild durian species, namely Durio kinabaluensis Kosterm. & Soegeng (durian tupoloh) and Durio oxleyanus Griff. (durian sukang) were studied. The 80% methanolic extracts of flesh, seed and peel (mesocarp and exocarp) were analysed for antioxidant activities, total phenolic and total flavonoid content. The antioxidant activities were determined using three parameters; 2,2-diphenyl-1-picrylhydrazyl radical assay (DPPH), 2,2’-Azino-bis (3-ethylbenzothiazoline-6- sulphonic acid) radical cation assay, and Ferric reducing antioxidant power assay (FRAP). Durio kinabaluensis mesocarp extract displayed the highest antioxidant properties and total phenolic content. The non-edible parts of both durians (seed and peel) exhibited higher phytochemical contents and antioxidant properties compared to the flesh parts. This data may contribute to the pharmaceutical applications, health benefit information of wild durians and helps in popularising the potential of these fruits in international markets and ultimately protects them from extinction