Cheng Hock Chuah

Separation of Vitamin E (tocopherol, tocotrienol, and tocomonoenol) in Palm Oil

Previous reports showed that vitamin E in palm oil consists of various isomers of tocopherols and tocotrienols [α-tocopherol (α−T), α-tocotrienol, γ-tocopherol, γ-tocotrienol, and δ-tocotrienol), and this is normally analyzed using silica column HPLC with fluorescence detection. In this study, an HPLC-fluorescence method using a C30 silica stationary phase was developed to separate and analyze the vitamin E isomers present in palm oil. In addition, an α-tocomonoenol (α−T1) isomer was quantified and characterized by MS and NMR. α−T1 constitutes about 3–4% (40±5 ppm) of vitamin E in crude palm oil (CPO) and is found in the phytonutrient concentrate (350±10 ppm) from palm oil, whereas its concentration in palm fiber oil (PFO) is about 11% (430±6 ppm). The relative content of each individual vitamin E isomer before and after interesterification/transesterification of CPO to CPO methyl esters, followed by vacuum distillation of CPO methyl esters to yield the residue, remained the same except for α−T and γ−T3. Whereas α−T constitutes about 36% of the total vitamin E in CPO, it is present at a level of 10% in the phytonutrient concentrate. On the other hand, the composition of γ−T3 increases from 31% in CPO to 60% in the phytonutrient concentrate. Vitamin is present at 1160±43 ppm, and its concentrations in PFO and the phytonutrient concentrate are 4,040±41 and 13,780±65 ppm, respectively. The separation and quantification of α−T1 in palm oil will lead to more in-depth knowledge of the occurrence of vitamin E in palm oil.

Lundurines A, B and C, new indole alkaloids with a novel carbon skeleton containing a cyclopropyl moiety

Abstract Three new indole alkaloids viz., Lundurines A, B and C, possessing a novel carbon skeleton incorporating a cyclopropyl unit were obtained from Kopsia tenuis. The structures of these alkaloids were elucidated by 2-D NMR methods.

Oxindole alkaloids from Alstonia macrophylla

Abstract Two new oxindole alkaloids, Nb-demethylalstophyllal oxindole and alstonal, together with three known alkaloids, Nb-demethylalstophylline oxindole, alstonisine and talcarpine, have been isolated from the bark of Alstonia macrophylla. Structures of the alkaloids were assigned by spectral methods

Application of supercritical fluid chromatography in the quantitative analysis of minor components (carotenes, vitamin E, sterols, and squalene) from palm oil

The application of supercritical fluid chromatography (SFC) coupled with a UV variable-wavelength detector to isolate the minor components (carotenes, vitamin E, sterols, and squalene) in crude palm oil (CPO) and the residual oil from palm-pressed fiber is reported. SFC is a good technique for the isolation and analysis of these compounds from the sources mentioned. The carotenes, vitamin E, sterols, and squalene were isolated in less than 20 min. The individual vitamin E isomers present in palm oil were also isolated into their respective components, α-tocopherol, α-tocotrienol, γ-tocopherol, γ-tocotrienol, and δ-tocotrienol. Calibration of all the minor components of palm as well as the individual components of palm vitamin E was carried out and was found to be comparable to those analyzed by other established analytical methods.

Kopsinitarines A B and C novel cage alkaloids from a Malaysian Kopsia

Abstract Novel indole alkaloids possessing an unprecedented cage skeletal system were isolated from a Malaysian Kopsia species and the structures were elucidated by spectral methods, especially 2-D NMR.

Kopsidine A and kopsidine B, two novel indole alkaloids from a Malaysian Kopsia

Abstract The ethanol extract of the leaves and stem-bark of Kopsia teoi provided a number of new indole alkaloids, two of these, kopsidine A and kopsidine B possess a novel heptacyclic skeletal system. The structures of these alkaloids were elucidated by 2-D NMR methods.

Rheological properties of cellulose nanocrystal-embedded polymer composites: a review

AbstractNanotechnology provides useful insights into the behavioural properties of materials from the nanoscale point of view, enabling researchers to develop new materials that were previously inconceivable. Cellulose is an ideal candidate for nanomaterial for nanotechnology because of its nanofibrillar structure, abundance, renewability, biodegradability and eco-friendly nature. Nanocrystalline cellulose materials have become the focus many studies related to these materials and their applications. This review summarises the current knowledge on the field of nanomaterials, focussing mainly on the rheological behaviour of polymer nanocomposites embedded with nanocrystalline cellulose. This review will enable better understanding of the use of nanocrystalline cellulose for the development and applications of cellulose nanocrystal-based nanocomposites.

Simultaneous quantification of free fatty acids, free sterols, squalene, and acylglycerol molecular species in palm oil by high-temperature gas chromatography-flame ionization detection

This paper discusses a rapid GC-FID technique for the simultaneous quantitative analysis of FFA, MAG, DAG, TAG, sterols, and squalene in vegetable oils, with special reference to palm oil. The FFA content determined had a lower SE compared with a conventional titrimetric method. Squalene and individual sterols, consisting of β-sitosterol, stigmasterol, campesterol, and cholesterol, were accurately quantified without any losses. This was achieved through elimination of tedious conventional sample pretreatments, such as saponification and preparative TLC. With this technique, the separation of individual MAG, consisting of 16∶0, 18∶0, and 18∶1 FA, and the DAG species, consisting of the 1,2(2,3)- and 1,3-positions, was sufficient to enable their quantification. This technique enabled the TAG to be determined according to their carbon numbers in the range of C44 to C56. Comparisons were made with conventional methods, and the results were in good agreement with those reported in the literature.

Aspidofractinine alkaloids from a new Kopsia species

Abstract Two new alkaloids of the aspidofractinine type, viz. kopsinginine and 17-α-hydroxy-Δ 14,15 -kopsinine, in addition to kopsingine and kopsaporine have been isolated from the bark of Kopsia teoi . The structures of the alkaloids were assigned by thorough analysis of their NMR spectra. The structure of kopsingine was also confirmed by X-ray diffraction analysis.

Extreme intraspecific chemical variability in soldier defense secretions of allopatric and sympatric colonies ofLongipeditermes longipes

The chemical defense secretions of major and minor soldiers of over 18 colonies of the primitive glue-squirting nasute termiteLongipeditermes longipes (Isoptera, Termitidae, Nasutitermitinae) were analyzed chormatographically. The colonies, collected from four rainforest sites in peninsular Malaysia, showed monoterpene patterns rich in pinenes and limonene but with few quantitative differences between colonies. In marked contrast, the diterpene chemistry is high variable, and includes tricyclic (trinervitane), tetracyclic (rippertane), bicyclic (secotrinervitane), and a new spirotetracyclic (longipane) skeleton. Three new natural products are included in this remarkable and unprecedented example of structural diversity among different colonies of a single species.