Planta Med 2016; 82(S 01): S1-S381
DOI: 10.1055/s-0036-1596495
Abstracts
Georg Thieme Verlag KG Stuttgart · New York

The Chemistry of African Croton species

MK Langat
1  Natural Products Research Group, Department of Chemistry, FEPS, University of Surrey, Guildford, GU2 7XH, UK
,
N Crouch
2  Biodiversity Research, Monitoring and Assessment, South African National Biodiversity Institute, PO Box 52099, Berea Road, 4007, Durban, South Africa
3  School of Chemistry and Physics, University of KwaZulu-Natal, Durban, 4041, South Africa
,
B Ndunda
4  Department of Chemistry, University of Nairobi, PO Box 30197 – 00100, Nairobi, Kenya
,
JO Midiwo
4  Department of Chemistry, University of Nairobi, PO Box 30197 – 00100, Nairobi, Kenya
,
A Aldhaher
1  Natural Products Research Group, Department of Chemistry, FEPS, University of Surrey, Guildford, GU2 7XH, UK
,
A Alqahtani
1  Natural Products Research Group, Department of Chemistry, FEPS, University of Surrey, Guildford, GU2 7XH, UK
,
DA Mulholland
1  Natural Products Research Group, Department of Chemistry, FEPS, University of Surrey, Guildford, GU2 7XH, UK
3  School of Chemistry and Physics, University of KwaZulu-Natal, Durban, 4041, South Africa
› Author Affiliations
Further Information

Publication History

Publication Date:
14 December 2016 (online)

 

The genus Croton is one of the largest of Euphorbiaceae sensu stricto, and consists of over 1300 species of trees, shrubs and herbs that are distributed worldwide in the warm tropics and subtropics. It is reported that 124 Croton species occur in continental Africa whilst a further 156 species are endemic to Madagascar. Another 12 species occur in the Indian Ocean islands of Comoros, Mauritius, Reunion and Sao Tome and Principe [1]. We discuss the chemistry, chemotaxonomic patterns and biological activities of selected compounds from ten African Croton taxa: C. alienus, C. dichogamus, C. gratissimus var. gratissimus, C. megalobotrys, C. megalocarpoides, C. megalocarpus, C. menyhartii, C. pseudopulchellus, C. rivularis and C. sylvaticus. Examples of compounds to be presented include cembranoids (1-3) from C. gratissimus var. gratissimus [2,3], ent-kauranes (4-5) from C. pseudopulchellus [4], ent-clerodanes (6-8) from C. sylvaticus, C. megalocarpus and C. megalocarpoidies, and both halimanes (9) and crotofolanes (10 – 11) from C. dichogamus. Triterpenoids, sesquiterpenoids, flavonoids and cyclohexanol derivatives from Croton will also be discussed. Selected cembranoids from C. gratissimus were tested against a chloroquine-sensitive strain of Plasmodium falciparum (D10) and against the PEO1 and PEO1TaxR ovarian cancer cell lines [2]. Compound 1 showed moderate activity against the PEO1 (IC50= 132 nM) and PEO1TaxR (IC50= 200 nM) ovarian cancer cell lines. Selected ent-kauranoids were tested for their effects on Semliki Forest Virus replication and for cytotoxicity against human liver tumour cells (Huh-7 strain). Other Croton-derived compounds were tested for antimicrobial and antifungal activities [5,6], antiplasmodial activity using two strains of Plasmodium falciparum, antileishmanial activities against Leishmania donovanii [5], and cytotoxic activity against NCI59 cancer cell panels, and colorectal and VERO cancer cell lines.

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Acknowledgements: University of Surrey, University of KwaZulu Natal and NRF-South Africa are acknowledged for funding.

Keywords: Croton, Euphorbiaceae, ent-clerodanes, cembranoids, crotofolanes.

References:

[1] WCSP (2016). 'World Checklist of Selected Plant Families. Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet; http://apps.kew.org/wcsp/Retrieved on 12th February 2016.'

[2] Mulholland DA, Langat MK, Crouch NR, Coley HM, Mutambi EM, Nuzillard J-M. Cembranolides from the stem bark of the southern African medicinal plant, Croton gratissimus (Euphorbiaceae). Phytochemistry 2010; 71: 1381 – 1386.

[3] Langat MK, Crouch NR, Smith PJ, Mulholland DA. Cembranolides from the Leaves of Croton gratissimus. J Nat Prod 2011; 74: 2349 – 2355.

[4] Langat MK, Crouch NR, Pohjala L, Tammela P, Smith PJ, Mulholland DA. Ent-kauren-19-oic acid derivatives from the stem bark of Croton pseudopulchellus Pax. Phytochem Lett 2012; 5: 414 – 418.

[5] Ndunda B, Langat MK, Wanjohi JM, Midiwo JO, Kerubo LO. Alienusolin, a new 4α-deoxyphorbol ester derivative, and crotonimide C, a new glutarimide alkaloid from the Kenyan Croton alienus. Planta Med 2013; 79: 1762 – 1766.

[6] Ndunda B, Langat MK, Midiwo JO, Omosa LK. Diterpenoid Derivatives of Kenyan Croton sylvaticus. Nat Prod Commun 2015; 10: 557 – 558.