Siow-Ping Tan

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• PhD (Chemistry)
• Professor (Associate) at Tunku Abdul Rahman University of Management and Technology

The hydantoin scaffold is renowned for its wide-ranging biological activities, including antibacterial, antiviral, anticancer, anti-inflammatory, and anticonvulsant effects. In this study, we present an innovative, sustainable approach to synthesizing hydantoins (H2a-j) directly from amino acids. This method employs a column chromatography-free, tw...

This research is intended to synthesize Sn-ZIF-8 with an environmentally friendly hydrothermal method by exploring the potential of the utilization of aqueous solvents as the main solvent. Sn-ZIF-8 material has been successfully synthesized with water solvent at room temperature and has been characterized using XRD, FTIR, and SEM instrumentation to...

2-(3 ' ,4 '-dihydroxyphenyl)-3,6,7,8-tetramethoxy-4H-chromen-4-one (3), a new flavonoid was isolated from the ethyl acetate fraction of Chrysanthemum morifolium Ramat. dried flowers, while 4′,5-dihydroxy-3,3′,7,8-tetra-methoxy-flavone (1) and casticine (5) were isolated from this plant for the first time, as well as two known flavonoids, eriodictyo...

The analysis of the constituents of the leaves of Tradescantia spathacea yielded one new phenolic compound, named 3,6-di-tert-butyl-5-ethylphenol (1), along with four known compounds consisting of 1,1′-oxybis(2,4-di-tert-butylbenzene), β-sitosterol, β-sitosterone, and stigmasterol. All the structures were depicted using different spectroscopic meth...

Background: Cervical cancer is the second most common cancer among women worldwide, with over 500,000 new cases diagnosed annually and a 50% mortality rate in Asia. The incidence and prevalence of cervical cancer is high in Asia due to limited screening, awareness of HPV infection, and access to vaccines. The purpose of this study is to evaluate th...

Tradescantia spathacea Sw. (T. Spathacea) belongs to the Commelinaceae family and has a wide range of pharmacological activities. This study aims to identify the classes of phytochemicals through phytochemical screening, quantify the antioxidant content via total phenolic content (TPC) and total flavonoid content (TFC) analyses, evaluate the antiox...

Murraya koenigii has been used in traditional Indian Ayurvedic medicine and in culinary as flavouring agents. The metabolites in the leaves of M. koenigii have been studied extensively for its pharmacological properties, revealing a diverse range of its therapeutic effects. This study aimed to investigate the metabolites in the leaf, bark, and root...

Strobilanthes crispa (L.) Blume (S. crispa) is a well-known folklore medicinal plant traditionally used in Malaysia and Indonesia for its diverse range of traditional applications and medicinal properties. While previous studies have established its effectiveness as an anticancer agent against various cancer types, its impact on skin cancer cells r...

Chrysanthemum morifolium is commonly prescribe as one of the ingredients in traditional Chinese medicine for gout treatment and pain relief from gout. This study aimed to study the interaction between apigenin, kaempferol and trans-cinnamic acid identified from C. morifolium in xanthine oxidase (XO) inhibition. In our previous study, apigenin, kaem...

Plant-derived natural products are an important source of potential medicines and continue to have a major impact on the drug discovery process. Natural product discovery assignments provide an opportunity to present various experimental techniques to undergraduate students in introductory medicinal chemistry. This assignment was developed to serve...

Clinacanthus nutans (Burm. f.) Lindau (C. nutans) is renowned in many tropical countries for its wide range of traditional uses and medicinal properties. This study qualitatively screened ethanol, hexane, and ethyl acetate (EA) leaf extracts of C. nutans for phytochemicals and evaluated their antioxidant activities using 2,2-diphenyl-1-picrylhydraz...

Strobilanthes crispa (L.) Blume (S. crispa) is a folklore medicinal plant of the genus Strobilanthes (Acanthaceae), traditionally used in Malaysia and Indonesia to treat various diseases such as breast and uterine cancers, diabetes mellitus, hypertension, gastrointestinal and kidney diseases, typhoid, jaundice, piles, high cholesterol, and ulcers....

Urea derivatives are an important class of pharmacologically-active compounds due to their ability to form hydrogen bonds with biological targets. Several synthetic pathways have been developed to access urea derivatives, such as the metal-free and metal-catalysed carbonylation reactions of amines and the Curtius, Hofmann, and Tiemann rearrangement...

A phytochemical study has been carried out on CH2Cl2 extract of Alphonsea cylindrica leaves, resulting in the isolation of three new morphinan alkaloids. They are kinomenine (1), N-methylkinomenine (2), and hydroxymethylkinomenine (3). The structures of these compounds were elucidated by extensive spectroscopic analysis (1D and 2D NMR, IR, UV, HRES...

Tradescantia spathacea Sw. (T. spathacea) is known for its antioxidant properties as it was used as a traditional medicine from the 16th to 19th century, and little research has been done on its phytochemical analysis on the roots. In this study, hexane and ethyl acetate root extracts of T. spathacea were analyzed for phytochemical, antioxidant and...

The leaves of Mitragyna speciosa were traditionally used by natives as a substitute for opium. Nowadays, recreational use of M. speciosa leaves is increasing and has become a concern because of the lack of information and studies about its potential health risks. This study evaluated the antioxidant, antimicrobial, and cytotoxic activities of the c...

Alphonsea cylindrica King belongs to the family Annonaceae, which is traditionally used to treat rheumatism, bruises, and edema. Investigation of its antibacterial properties was carried out on hexane and dichloromethane crude extracts using agar diffusion method and minimum inhibitory concentration against ESKAPE pathogens. Both extracts showed po...

The Urech hydantoin synthesis is the chemical reaction of amino acids with potassium cyanate and hydrochloric acid, which allows access to hydantoins and its derivatives. Most of them are biologically active with varieties of structural diversity that make them synthetically attractive. A series of hydantoins were synthesized from various α-amino a...

Phyllanthus acidus (L.) Skeels (Phyllanthaceae family) is a plant that is widely distributed in Asian countries, which is traditionally used as a medicinal plant to treat various ailments. Inspired by the uses of the plant, the aim of this study was to extract and isolate bioactive compounds from P. acidus as potential antimicrobials. The isolation...

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 char-acterization of these compounds were determined by 1D and 2D NMR experiments. These compounds showed no cytotoxic activity a...

Murraya koenigii (L.) Spreng. is a member of the Rutaceae family, which is commonly grown in home gardens in Malaysia. It is a highly valuable plant because of its characteristic aroma and medicinal value.

Ethnopharmacological relevance: Phyllanthus acidus (L.) Skeels is not only used for its edible fruits but also used to treat a wide spectrum of diseases such as inflammatory, rheumatism, bronchitis, asthma, respiratory disorder, hepatic diseases and diabetes in India, Asia, the Caribbean region, and Central and South America. This paper aims to di...

Non-polar crude extracts obtained from the calyces of Hibiscus sabdariffa Linn. (Roselle) and their α-glucosidase inhibitory activity has been investigated. Roselle extracts potentially act as an anti-diabetic activity. However, most of the previous studies on Roselle were just focused on the polar crude extracts. Therefore, hexane and dichlorometh...

Phyllanthus amarus which is locally known as Dukung Anak was one of the herb used in traditional medicine and research of P. amarus in Malaysia was not widely reported. This present research has isolated three chemical compounds and its anticancer effect of this species has been determined. Three lignans namely hypophyllanthin was afforded from hex...

Background Phytochemical investigation of the bark of Phyllanthus acidus (L.) Skeels led to the isolation of two chemical entities, namely meso-hydrobenzoin (1), 2-ethylhexyl isonicotinate (2) and squalene (3) via chromatography methods. Methods The structures of these compounds were characterised and identified by spectral analyses, such as NMR...

The FeCl3-catalyzed cross-coupling through a sequential C−N and C−C bond-forming via tandem C−H and N−H bonds functionalization represents a novel method for the formation of dimeric carbazole derivatives. This approach provides a novel dimeric carbazole, namely murrabicine (4), from murrayacine (1). Following the same procedure, a cycloadduct (6)...

The purpose of this study is to isolate and identify alkaloid compounds from the roots of Malayan Murraya koenigii. This plant has been reported to be rich in carbazole alkaloid. The hexane and dichloromethane crude extracts (roots) were separated using thin layer and column chromatography techniques. Four carbazole alkaloids were afforded and iden...

Murraya koenigii, locally known as "kari" tree, was selected for the phytochemical analysis. The extraction and isolation of the carbazole alkaloids from its n-hexane extract of the bark was carried out by using various chromatographic techniques. Three cyclic monoterpenoid pyranocarbazole alkaloids namely, murrayazolinol, murrayakoeninol and bicyc...

Six new carbazole alkaloids, murrastanine-A (1), murrastinine-A, -B, -C (2-4), murrayatanine-A (5) and bismahanimboline (6), were isolated from the bark and leaves of Murraya koenigii (Linn.) Spreng along with 24 known carbazole alkaloids. The structure of these compounds were elucidated by extensive spectroscopic analysis. Murrastinine-C (4) and m...

Six indole alkaloids; kopsamine N(4)-oxide 1, kopsifine 2, rhazinicine 3, aspidodasycarpine 4, kopsamine 5 and akuammidine 6, were isolated from the roots of Kopsia singapurensis Ridl. (Apocynaceae). Compound 2 is first time isolated from the roots of K. singapurensis Ridl. Those compounds were screened for in vitro cytotoxic activity against human...

Murraya koenigii (L.) (Rutaceae) is an indigenous medicinally important herb of Indian origin and now is widely distributed throughout southern Asia. The stem bark, leaves and roots of Malayan Murraya koenigii were selected for phytochemical investigation. Eight carbazole alkaloids was isolated and identified using spectroscopic methods including N...

Kopsia singapurensis Ridl. is one of the species of the genus Kopsia, also called white kopsia or locally known as ‘selada’ which about 18 species were distributed in Malaysia. This species is endemic only to Peninsular Malaysia and Singapore. This plant is known to produce a large number of biologically active compounds. In the present study, six...

Murraya koenigii (Curry leaf tree), from the Rutaceae family, is a medicinally important herb of Indian origin and now were widely distributed throughout southern Asia. The bark of Malayan Murraya koenigii was selected for phytochemical investigation. The isolation of chemical constituents from its hexane and dichloromethane extract was carried out...

Four indole alkaloids,viz., kopsifine 1, kopsamine2, kopsamine N(4)-oxide3, and rhazinicine 4 have been isolated from the roots of Kopsia singapurensis Ridl. The structures of these known indole alkaloids were established by NMR spectral data using various 1D-NMR (1H, 13C & DEPT) and 2D-NMR (COSY, HMQC & HMBC) techniques and also by comparison with...

Murraya koenigii (Rutaceae), locally known as curry leaf tree, is a medicinally important herb of Indian origin and now were widely distributed throughout southern Asia. The bark of Murraya koenigii was selected for phytochemical investigation. The isolation of chemical constituents from its hexane extract was carried out by using different chromat...

Study on chemical constituents from Kopsia singapurensis (Apocynaceae) yielded four new aspidofractinines: Singaporentine A (1), N(1)-formylkopsininic acid (2), N(1)-formylkopsininic acid-N(4)-oxide (3), 15-hydroxykopsamine (4); a new aspidospermatan: 14α-hydroxy-N(4)-methylcondylocarpine (5) and a new akuamiline: singaporentinidine (6) together wi...

Murraya koenigii (Curry Leaf), belonging to the Rutaceae family, is native to India and now were also distributed throughout southern Asia. Phytochemical investigation on hexane extract of the bark of Malayan Murraya koenigii has led to the isolation and identification of three pyranocarbazole alkaloids: girinimbine 1, mahanimbine 2 and murrayamine...

In Malaysia, Alstonia spathulata Bl. is locally known as ‘pulai basong’ which distribute in peat forest. The separation of the chemical components from hexane crude extract (bark) of Alstonia spathulata was carried out using different chromatographic techniques (column chromatography and thin layer chromatography). Two compounds were isolated and i...