Anticholinesterase and antifungal of some iridoids from the flower of Allamanda cathartica (Apocynaceae)

Allamanda cathartica L. (Apocynaceae) have been used traditionally in medicinal practices to cure symptoms and complications of some diseases in several countries [1]. As a measure to unleash other medicinal uses, the isolated compounds were tested for potential anticholinesterase activity and antifungal testing on human phatogen. Our latest isolation work yielded some iridoids; plumieride (1), plumieride p-Z-coumarate (2), plumericin (3), and allamandicin (4) from the acetonic extract of the flowers by using a combination of vacuum liquid chromatography, column chromatography, radial chromatography and preparative thin layer chromatography techniques. The molecular structures of the isolated compounds were established based on the spectroscopic data and compared with previous reported data [2].

For the anticholinesterase inhibitory activity, these iridoids were screened by using in vitro Ellman method (tacrine as positive control)[3]. Plumericin and allamandicin respectively exhibited inhibitory activities IC25 at 1543.9 mg/ml and 434 mg/ml. Plumieride showed low inhibition up to 3 mg/ml and inhibitory activity not up to 25%. These iridoids also known for their antifungal properties based from past research [4]. To investigate the antifungal activity of these iridoids, they were tested on Candida albicans, Rhodotorula sp., and Aspergillus sp. by using agar plate diffusion method. In this work, plumeriede showed diameter of inhibited zone against C. albicans (18 mm) and Aspergillus sp. (15 mm). These result indicated that these iridoids have positive response to the tests.

Acknowledgements: The authors would like to thank The Institute of Graduate Studies, UiTM Shah Alam, Malaysia for the financial support under the Graduate Service Scheme and Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM) Shah Alam for providing research facility.

Keywords: Allamanda cathartica, iridoids, anticholinesterase, antifungal.

References:

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[2] Coppen JJW. Iridoids with algicidal properties from Allamanda Cathartica. Phytochemistry 1983; 22: 179 – 182

[3] Ahmad R, Baharum SN, Bunawan H, Lee M, Noor NM, Rohani ER, Ilias N, Zin NM. Volatile profiling of aromatic traditional medicinal plant, Polygonum minus in different tissues and its biological activities. Molecules 2014; 19: 19220 – 19242

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