M. Mohtar

Chemical composition and antimicrobial activities of the essential oils of Cinnamomum aureofulvum Gamb.

Abstract The leaf and bark oils of Cinnamomum aureofulvum Gamb. were analyzed by GC and GC/MS. The leaf oil was made up predominantly of benzyl benzoate (43.4%), benzyl alcohol (8.1%) and linalool (7.3%), whereas the bark oil contained cinnamaldehyde (46.6%), linalool (14.6%) and eugenol (5.0%) as the major components. The oils were screened for antibacterial activity against two Gram positive bacteria (Staphylococcus aureus and S. epidermidis) and two Gram negative bacteria (Pseudomonas cepacia and P. aeruginosa) and antifungal activity against two Candida species (C. albicans and C. glabrata) and three dermatophytes (Microsporum canis, Trichophyton mentagrophytes and 7′. rubrum) by using the broth microdilution method. The oils exhibited insignificant activity against all the bacteria except P. aeruginosa, which was observed to be sensitive to the bark oil with MIC value of 1.87 μg/μ.L. They demonstrated moderate to strong activities towards all the fungi tested except C. glabrata, with MIC values ranging from 0.63 to 2.50 μg/μL. Among the fungi, M. canis was the most susceptible, with both oils exhibiting their lowest MIC values towards the fungi. The bark oil was found to be more effective than the leaf oil and their activity was mainly due to their respective major components.

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.

Efflux inhibitory activity of flavonoids from Chromolaena odorata against selected methicillin- resistant Staphylococcus aureus (MRSA) isolates

Antimicrobial Laboratory, Bioactivity Programme, Natural Products Division, Forest Research Institute Malaysia (FRIM), Selangor, Malaysia. Phytochemistry Programme, Natural Products Division, Forest Research Institute Malaysia (FRIM), Selangor, Malaysia. Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia (UPM), Selangor, Malaysia. Faculty of Agriculture and Biotechnology, Universiti Sultan Zainal Abidin (UniSZA), Kuala Terengganu, Malaysia.

In Vitro Inhibitory and Cytotoxic Activity of MFM 501, a Novel Codonopsinine Derivative, against Methicillin-Resistant Staphylococcus aureus Clinical Isolates

28 new pyrrolidine types of compounds as analogues for natural polyhydroxy alkaloids of codonopsinine were evaluated for their anti-MRSA activity using MIC and MBC value determination assay against a panel of S. aureus isolates. One pyrrolidine compound, MFM 501, exhibited good inhibitory activity with MIC value of 15.6 to 31.3 μg/mL against 55 S. aureus isolates (43 MRSA and 12 MSSA isolates). The active compound also displayed MBC values between 250 and 500 μg/mL against 58 S. aureus isolates (45 MRSA and 13 MSSA isolates) implying that MFM 501 has a bacteriostatic rather than bactericidal effect against both MRSA and MSSA isolates. In addition, MFM 501 showed no apparent cytotoxicity activity towards three normal cell lines (WRL-68, Vero, and 3T3) with IC50 values of >625 µg/mL. Selectivity index (SI) of MFM 501 gave a value of >10 suggesting that MFM 501 is significant and suitable for further in vivo investigations. These results suggested that synthetically derived intermediate compounds based on natural products may play an important role in the discovery of new anti-infective agents against MRSA.

In Vitro Evaluations and In Vivo Toxicity and Efficacy Studies of MFM501 against MRSA

Previously we have discovered a synthetically derived pyrrolidone alkaloid, MFM501, exhibiting good inhibitory activity against 53 MRSA and MSSA isolates with low cytotoxicity against three normal cell-lines with IC50 values at >625 µg/ml. Time-kill assay, scanning electron microscopy (SEM) analysis, in vivo oral acute toxicity test, and mice peritonitis model were carried out in this study. In the time-kill study, MFM501 showed a less than 3 log10 decrease in bacterial colony concentration value (CFU/ml) which represented a bacteriostatic action while displaying a time-dependent inhibitory mechanism. Following that, SEM analysis suggested that MFM501 may exert its inhibitory activity via cytoplasmic membrane disruption. Moreover, MFM501 showed no toxicity effect on treated mice at an estimated median acute lethal dose (LD50) value of more than 300 mg/kg and less than 2000 mg/kg. For the efficacy test, a mean effective dose (ED50) of 87.16 mg/kg was obtained via a single dose oral administration. Our data demonstrated that MFM501 has the potential to be developed further as a new, safe, and effective oral-delivered antibacterial agent against MRSA isolates.

Chemical compositions and antimicrobial activity of twig essential oils from three Xylopia (Annonaceae) species

The chemical composition of twig essential oils of Xylopia malayana , Xylopia elliptica and Xylopia fusca were analyzed using GC and GCMS. Both X. malayana (12.9%) and X. fusca (11.8%) twig oils contained spathulenol as the major constituent while X. elliptica twig oil was found to be rich in terpinen-4-ol (11.9%). The antimicrobial activities of the essential oils were evaluated against six gram positive bacteria, two gram negative bacteria and yeast by using the broth microdilution method. The twig oil of X. elliptica at a concentration ranging from 156 to 625 μg/ml was found to be active against all bacterial and yeast strains tested. Both X. malayana and X. fusca twig oils demonstrated weak activity toward all microorganisms tested with the MIC value of 5000 μg/ml. Gram negative bacteria’s, Pseudomonas aeruginosa and Escherichia coli seemed to be resistant to the essential oils tested. α-Pinene showed moderate to strong inhibitory effect against all the microorganism strains tested with the MIC value ranging from 325 to 2500 μg/ml, as compared to the other standard compounds which showed weak inhibitory even at the highest concentrations used. This finding demonstrated that the twig oil of X.elliptica possesses antimicrobial activity which may be useful and potential ingredient in the production of health care products. Key words: Xylopia twigs, essential oils, GC & GCMS analysis, antimicrobial activity.