Planta Med 2014; 80 - P1L152
DOI: 10.1055/s-0034-1394809

Abietane diterpenes from Plectranthus madagascariensis: A cytotoxicity screening

D Matias 1, 2, F Pereira 1, M Nicolai 1, A Roberto 1, N Saraiva 1, AS Fernandes 1, MF Simões 1, 3, AD Lanza 2, CP Reis 1, P Rijo 1, 3
  • 1Universidade Lusófona Research Center for Biosciences & Health Technologies (CBIOS), Campo Grande, 376, 1749 – 024 Lisboa
  • 2Dpto. Ciencias Biomédicas, Univesidad de Alcalá, Plaza de San Diego, s/n, 28801 Alcalá de Henares, Madrid, Espanha
  • 3Instituto de Investigação do Medicamento (iMed.ULisboa), Faculdade de Farmácia da Universidade de Lisboa, Av. Professor Gama Pinto 1649 – 003 Lisboa

Plectranthus genus (Lamiaceae) includes interesting plants with medicinal uses. Their ethnopharmacological application as anti-infectious medicines has been correlated with the presence of bioactive diterpenes that frequently show cytotoxicity against human tumour cell lines [1 – 3]. This study describes the cytotoxic screening carried out with extracts of Plectranthus species P. madagascariensis Benth., P. neochilus Schltr. and P. porcatus Winter & Van Jaarsv. A total of 26 aqueous, acetonic and methanolic extracts from the three Plectranthus species were obtained using different extraction techniques. The aqueous extracts were prepared by infusion, decoction and microwave techniques. The organic extracts were prepared by maceration, ultrasounds and supercritical carbon dioxide extraction methods. All the extracts were tested for their cell toxicity using a crystal violet assay in MDA-MB-231 breast cancer cells. The acetonic P. madagascariensis extract obtained by maceration was the most cytotoxic with IC50 values of ≈ 64 µg/ml. The bioactive extract was submitted to a cytotoxicity bioguided fractionation by different chromatographic techniques including semi-preparative HPLC. Compounds 7α-acetoxy-6β-hydroxyroyleanone 1 and coleon U 2 were identified with HPLC-DAD by comparison with the standard diterpenes previously isolated from P. grandidentatus [2] and confirmed using spectroscopic methods. We report the first cytotoxicity bioguided fractionation of a P. madagascariensis acetonic extract. The high levels of cytoxicity of the bioactive extract may be at least partially due to diterpenes 1 and 2, which are known antiproliferative abietanes [2,3]. P. madagascariensis species seems to be a good raw vegetal material for the isolation of lead anticancer drugs for further modulation.

Fig. 1: Abietane diterpenes 7α-acetoxy-6β-hydroxyroyleanone 1 and coleon U 2.

Acknowledgments: This project is supported by the grant PADDIC 2013 – 2014, from ALIES-COFAC and part of the PhD Program in Health Sciences from U. Alcalá and U. Lusófona.

Keywords: Plectranthus, Plectranthus madagascariensis, HPLC-DAD, diterpenes, cytotoxicity

References:

[1] Lukhoba CW, Simmonds MSJ, Paton AJ. Plectranthus: A review of ethnobotanical uses.J Ethnopharmacol. 2006; 103(1): 1 – 24

[2] Marques CG, Pedro M, Simoes MF, Nascimento MS, Pinto MM, Rodriguez B. Effect of abietane diterpenes from Plectranthus grandidentatus on the growth of human cancer cell lines. Planta Med. 2002; 68(9): 839 – 40

[3] Burmistrova O, Simões MF, Rijo P, Quintana J, Bermejo J, Estévez F. Antiproliferative Activity of Abietane Diterpenoids against Human Tumor Cells. J Nat Prod. 2013; 76(8): 1413 – 23.