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22 record(s) found

Isolation Of Stigmasterol from the leaves of Kopsia Singapurensis RIDL

Lee Yean Shan, Ahmad Kartini, Awang Khalijah, Tan Siow Ping, Nafiah Mohd Azlan,

Abstract

The isolation and purification of the leaves of Kopsia singapurensisRidl. (Apocynaceae) revealed the presence of steroids, terpenes, and alkaloids. Stigmasterol 1 was isolated from the hexane crude extract of the leaves of this species. This phytochemical study involves extraction, separation by using various chromatographic methods and structural determination by spectroscopic technique such as IR, NMR including 1D-NMR (1H, 13C and DEPT), 2D-NMR (COSY, NOESY, HMQC/HSQC, and HMBC) and GCMS, involving also comparison with data from the literature..

Conference Item Published 2012 6391 hits Available

Chemical Constituent from Alstonia Spathulata BL. (Apocynaceae)

Tee Chuan Thing, Ahmad Kartini, Awang Khalijah, Tan Siow Ping, Nafiah Mohd Azlan,

Abstract

In Malaysia, Alstonia spathulataBl. is locally known as pulai basong which distribute in peat forest. The separations of the chemical components from hexane crude extract (bark) of Alstonia spathulata were carried out using different chromatographic techniques (column chromatography and thin layer chromatography). One compound were isolated and identified as lupeol acetate (1). This compound have never been reported and isolated from this species. The structures of this compound were elucidated based on the basis of detailed 1D-NMR (1H, 13C and DEPT) and 2DNMR (COSY, HSQC, HMBC) spectroscopic analysis. The data analysis was also compared with the literature...

Conference Item Published 2012 6158 hits Available

Phytochemical analysis of Murraya Koenigii (Rutaceae) and in Vitro Cytotoxic activity of its isolated compounds and the synthetic analogues of Girinimbine and Mahanimbine

Tan, Siow Ping

Abstract

The objectives of the study are to determine the phytochemical constituents from the bark and leaves of Murraya koenigii, to develop synthetic analogues from girinimbine and mahanimbine via Lewis acid-mediated reactions, and to evaluate cytotoxic activities. The isolation and purification of the chemical compounds were done by using various chromatography methodologies. These compounds were then structurally identified by various spectroscopic techniques such as NMR, IR, UV and mass spectrometry. In vitro cytotoxic activities were evaluated against human promyelocytic leukemia (HL-60), cervical cancer cell lines (HeLa) and the normal mouse embryonic fibroblasts (NIH/3T3) cell lines via MTT assay. As the findings, phytochemical analysis on bark and leaves of M. koenigii afforded a total of 36 chemical compounds included six new carbazoles, viz., murrastanine-A, murrastinine-A, -B and -C, murrayatanine-A and bismahanimboline. Besides, two girinimbine analogues, viz., murranimbine and epo.....

Thesis Published 2015 2210 hits Available

C23-Carbazole Alkaloids from the bark of Murraya koenigii (L.) Spreng

Tan Siow Ping, Nafiah Mohd Azlan, Ahmad Kartini,

Abstract

Murraya koenigii (Rutaceae), locally known as curry leaf tree, is a medicinally important herb of Indian origin and now is widely distributed throughout southern Asia. The bark of Malayan Murraya koenigii was investigated for phytochemical content. The isolation of chemical constituents from its hexane extract was carried out by using various chromatographic techniques. Spectroscopic methods, including NMR, IR, UV, MS spectra data, were used for the structural characterization. Four C23-carbazole alkaloids were isolated..

Article Published 2014 3555 hits Available

Phytochemical study of stem bark from Alstonia spathulata Bl. (Apocynaceae)

Tee Chuan Thing, Lee Yean Shan, Tan Siow Ping, Awang Khalijah, Nafiah Mohd Azlan, Ahmad Kartini,

Abstract

In Malaysia, Alstonia spathulata Bl. is locally known as ‘Pulai Basong’ which distribute in peat forest. The separation of the chemical components from hexane and DCM crude extract of Alstonia spathulata was carried out using column chromatography (CC) and thin layer chromatography (TCL) techniques. A total of five known compound were isolated from the stem bark extracts and identified as: β-amyrin, β-amyrin acetate, lupeol acetate, stigmasterol and β-sitosterol. The elucidation structures of these compounds were established using 1D-NMR (1H, 13C and DEPT) and 2D-NMR (COSY, HSQC, HMBC) spectroscopic analysis, involving also comparison with data from the literature...

Article Published 2014 4163 hits Available

Steroids and terpenoids from the bark of phyllanthus acidus

Tan Siow-Ping

Abstract

[No abstract available]..

Article Published 2021 1460 hits Available

Keberkesanan penggunaan peta pemikiran I-Think dalam menyelesaikan masalah Matematik berayat dalam kalangan murid tahun lima

Khoo, Yee Ping

Abstract

Kajian ini bertujuan menilai keberkesanan penggunaan peta pemikiran i-Think bagi menyelesaikan masalah matematik berayat dalam kalangan murid Tahun Lima. Pembinaan modul i-Think Penyelesaian Masalah Matematik Berayat (iPMMB) adalah berdasarkan adaptasi model ADDIE. Pendekatan kuantitatif dalam bentuk kuasi eksperimen telah digunakan dalam kajian ini. Pemilihan subjek kajian telah dijalankan secara persampelan berkelompok yang melibatkan 55 orang murid di sebuah Sekolah Rendah Jenis Kebangsaan di daerah Hilir Perak. Tiga instrumen kajian digunakan iaitu modul iPMMB, borang soal selidik dan ujian pencapaian iaitu ujian pra dan ujian pasca. Data dianalisis dengan analisis deskriptif dan inferensi. Analisis deskriptif menjelaskan minat murid dalam menyelesaikan masalah matematik berayat dengan peta pemikiran i-Think, manakala analisis inferensi pula melibatkan ujian-t bagi menunjukkan perbezaan antara pemboleh ubah kajian. Hasil dapatan menunjukkan bahawa penggunaan peta pemikiran i-Think .....

Thesis Published 2017 3244 hits Available

Kesilapan sebutan nada bahasa Mandarin dalam kalangan pelajar Melayu

Chuah, Kee Ping

Abstract

Kajian ini bertujuan untuk mengenal pasti dan menganalisis kesilapan sebutan nada serta membanding persepsi pelajar terhadap kesukaran sebutan nada dan kesilapan sebenar dalam sebutan nada Bahasa Mandarin dalam kalangan pelajar Melayu. Kajian deskriptif berdasarkan tinjauan ini melibatkan 88 orang pelajar UiTM yang mengikuti kursus Bahasa Mandarin sebagai subjek kajian ini. Rakaman suara bacaan sebutan kata dwisuku dianalisis dengan perisian Praat untuk menganalisis dan mengenal pasti kesilapan sebutan nada. Soal selidik diedarkan kepada subjek kajian untuk mengenal pasti dan menganalisis serta membanding persepsi pelajar terhadap kesukaran sebutan nada kata dwisuku dengan kesilapan sebenar yang dilakukan. Dapatan kajian menunjukkan bahawa persepsi pelajar terhadap kesilapan sebutan nada adalah tidak selaras dengan hasil analisis sebenar. Maka, penekanan terhadap semua kategori sebutan nada kata dwisuku adalah diperlukan. Kesilapan interlingual, intralingual, dan developmental dan pers.....

Thesis Published 2016 3060 hits Available

Terpenes and phenolic compounds of Murraya Koenigii

Siow-Ping, Tan

Abstract

Murraya koenigii (L.) Spreng, an evergreen plant, is mostly distributed in tropical and subtropical regions [1]. It belongs to the Murraya genus of the Rutaceae family, which is widely grown in home gardens in Malaysia for its aromatic leaves and as one of the important ingredients in Indian cuisine. Previous phytochemical studies on M. koenigii revealed the presence of carbazole alkaloids [2–7] and coumarins [8]. Herein, we present data on the isolation and identification of three triterpenes and two phenolic compounds from the hexane crude extracts of the bark and leaves of M. koenigii collected from Pahang, Malaysia. The hexane crude extract of the bark (30.0 g) was chromatographed over silica gel 60F254 (70–230 mesh) and extensively subjected to silica gel 60F254 (230–400 mesh) column chromatography and preparative TLC on silica gel GF254, leading to the isolation of compounds 1–3, and 5. Meanwhile, compounds 1, 4, and 6 were isolated from the leaves hexane extract (20.0 g).....

Article Published 2017 1320 hits Limited

A simple BF3 Et2O-mediated cycloaddition reaction to the formation of cyclic monoterpenoid pyrano[3,2-a]carbazole alkaloids

Tan, Siow-Ping

Abstract

A Lewis acid BF3?Et2O-mediated intramolecular cycloaddition reaction of mahanimbine (1) is described. Three cycloadducts, bicyclomahanimbine (2), cyclomahanimbine (3) and murrayazolinine (4) were obtained. The structural characterization of these compounds was determined by 1D and 2D NMR experiments. These compounds showed no cytotoxic activity against human MRC-5 cells (IC50 > 60 ?g/mL). Compound 3 showed the highest inhibition cytotoxic effects against HeLa and HL-60 cancer cells with IC50 values of 10.0 and 28.7 ?g/mL, respectively. This strategy opens a new approach for the synthesis of biologically significant cyclic monoterpenoid pyrano[3,2-a]carbazole alkaloids. ? 2021 Bentham Science Publishers...

Article Published 2021 1380 hits Available

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