Rasadah Mat Ali

Systematic analysis of in vitro photo-cytotoxic activity in extracts from terrestrial plants in Peninsula Malaysia for photodynamic therapy

One hundred and fifty-five extracts from 93 terrestrial species of plants in Peninsula Malaysia were screened for in vitro photo-cytotoxic activity by means of a cell viability test using a human leukaemia cell-line HL60. These plants which can be classified into 43 plant families are diverse in their type of vegetation and their natural habitat in the wild, and may therefore harbour equally diverse metabolites with potential pharmaceutical properties. Of these, 29 plants, namely three from each of the Clusiaceae, Leguminosae, Rutaceae and Verbenaceae families, two from the Piperaceae family and the remaining 15 are from Acanthaceae, Apocynaceae, Bignoniaceae, Celastraceae, Chrysobalanaceae, Irvingiaceae, Lauraceae, Lythraceae, Malvaceae, Meliaceae, Moraceae, Myristicaceae, Myrsinaceae, Olacaceae and Sapindaceae. Hibiscus cannabinus (Malvaceae), Ficus deltoidea (Moraceae), Maranthes corymbosa (Chrysobalanaceae), Micromelum sp., Micromelum minutum and Citrus hystrix (Rutaceae), Cryptocarya griffithiana (Lauraceae), Litchi chinensis (Sapindaceae), Scorodocarpus bornensis (Olacaceae), Kokoona reflexa (Celastraceae), Irvingia malayana (Irvingiaceae), Knema curtisii (Myristicaceae), Dysoxylum sericeum (Meliaceae), Garcinia atroviridis, Garcinia mangostana and Calophyllum inophyllum (Clusiaceae), Ervatamia hirta (Apocynaceae), Cassia alata, Entada phaseoloides and Leucaena leucocephala (Leguminosae), Oroxylum indicum (Bignoniaceae), Peronema canescens,Vitex pubescens and Premna odorata (Verbenaceae), Piper mucronatum and Piper sp. (Piperaceae), Ardisia crenata (Myrsinaceae), Lawsonia inermis (Lythraceae), Strobilanthes sp. (Acanthaceae) were able to reduce the in vitro cell viability by more than 50% when exposed to 9.6J/cm(2) of a broad spectrum light when tested at a concentration of 20 microg/mL. Six of these active extracts were further fractionated and bio-assayed to yield four photosensitisers, all of which are based on the pheophorbide-a and -b core structures. Our results suggest that the main photosensitisers from terrestrial plants are likely based on the cyclic tetrapyrrole structure and photosensitisers with other structures, if present, are present in minor amounts or are not as active as those with the cyclic tetrapyrrole structure.

Antimicrobial and antiinflammatory activities of extracts and constituents of Oroxylum indicum (L.) Vent

Dichloromethane extracts of the stembark and root of Oroxylum indicum were found to have antimicrobial activities against Gram positive bacteria (Bacillus subtilis and Staphylococcus aureus), Gramnegative bacteria (Escherichia coli and Pseudomonas aeruginosa) and a yeast (Candida albicans). Bioassay-guided chromatographic fractionation led to the isolation of flavonoids (bacailein and chrysin) and a naphthoquinone, lapachol. Lapachol was found active against the Gram-positive bacteria, 5 μg giving a zone of inhibition equivalent to that shown by 5 μg streptomycin, whereas 5 μg chrysin gave inhibition zones of equal size to 5 μg streptomycin against Candida albicans and Pseudomonas aeruginosa. The inhibitory activity of lapachol from O. indicum root against soya 5-lipoxygenase (IC(50) 0.79 μg/ml) was equivalent to that of the positive control fisetin (IC(50) 0.97 μg/ml) and 50 μg/ml of the dichloromethane extract of the rootbark gave 100% inhibition of leukocyte lipoxygenase. These activities might indicate an antiinflammatory effect for the dichloromethane extract, mainly due to the lapachol content.

Antifungal activity of some Bignoniaceae found in Malaysia

The dichloromethane extracts of Tabebuia chrysantha, Oroxylum indicum, Fernandoa adenophylla and Jacaranda filicifolia display antifungal activity against dermatophytes and wood rot fungi. The activity is probably due mainly to lapachol and β‐lapachone which were shown to be present in these plant extracts. Microscopical study has shown that these extracts inhibit the development of mycelium and conidia in the filamentous fungi.

Chemical Constituents and Antimicrobial Activity of the Leaf and Rhizome Oils of Alpinia pahangensisRidl., an Endemic Wild Ginger from Peninsular Malaysia

The essential oils from the leaves and rhizomes of Alpinia pahangensis Ridl., collected from Pahang, Peninsular Malaysia, were obtained by hydrodistillation, and their chemical compositions were determined by GC and GC/MS analyses. The major components of the rhizome oil were γ‐selinene (11.60%), β‐pinene (10.87%), (E,E)‐farnesyl acetate (8.65%), and α‐terpineol (6.38%), while those of the leaf oil were β‐pinene (39.61%), α‐pinene (7.55%), and limonene (4.89%). The investigation of the antimicrobial activity of the essential oils using the broth microdilution technique revealed that the rhizome oil of A. pahangensis inhibited five Staphylococcus aureus strains with minimum inhibitory concentration (MIC) values between 0.08 and 0.31 μg/μl, and four selected fungi with MIC values between 1.25 and 2.50 μg/μl.