Chemical constituents from Elytropappus rhinocerotis (L.f.) Less. Bongiwe P. Mshengu, Emmanuel Gakuba, Fanie R. van Heerden * School of Chemistry and Physics, University of KwaZulu-Natal, Private Bag X01, Scottsville 3209, Pietermaritzburg, South Africa article info Article history: Received 22 June 2017 Received in revised form 25 October 2017 Accepted 26 October 2017 Keywords: Elytropappus rhinocerotis Asteraceae Flavone Labdane Diterpenoid abstract Phytochemical investigation of the ethyl acetate extract of the aerial parts of Elytropappus rhinocerotis (L.f.) Less. led to the isolation of a coumarin (1), four flavonoids (2e5), and four labdane diterpenes (6e9). The structural characterization of the isolated compounds was based on spectroscopic data. All com- pounds are reported for the first time from this species and from the genus Elytropappus Cass. The isolation of labdane diterpenes and methoxylated flavones is of taxonomical significance. © 2017 Elsevier Ltd. All rights reserved. 1. Subject and source Elytropappus rhinocerotis (L.f.) Less. (commonly known as “renosterbos” or rhinoceros bush) is widely used in traditional medicine in South Africa (Hutchings et al., 1996; Van Wyk et al., 2008; Van Wyk et al., 2012; Watt and Breyer-Brandwijk, 1962). The aerial parts (leaves and branches) of E. rhinocerotis were collected in December 2008 from the farm Weltevrede in Murraysburg (Western Cape, South Africa; 32.1182 S, 24.0095 E). The plant was identified by Mrs. Alison Young (University of KwaZulu-Natal Botanical Garden) and the voucher specimen (van Heerden 3, image in Supplementary Data) was deposited at the Bews Herbarium (University of KwaZulu- Natal). The plant material was authenticated by comparison with the voucher specimen Elytropappus NU002 in the Bews Herbarium, collected by N Pocock in 1949. 2. Previous work In previous investigations, rhinocerotinoic acid (Dekker et al., 1988), cirsimaritin, hispidulin, eupafolin, quercetin, benzoic acid and cinnamic acid derivatives (Proksch et al., 1982), (S)-4 0 ,5- dihydroxy-7-methoxyflavanone and (S)-4 0 ,5-dihydroxy-3 0 ,7- dimethoxyflavanone (Ticha et al., 2015) were isolated from this plant. Gray et al. (2003) was not able to re-isolate rhinocerotinoic acid from the plant material collected in the Eastern Cape province of South Africa. 3. Present study The aerial parts of E. rhinocerotis were air dried, ground into a powder and then extracted with a mixture of methanol (MeOH)- dichloromethane (DCM) (50:50, v/v) at room temperature for 48 h. This yielded 189 g of crude extract and this was re-dissolved in acetone and subjected to silica gel column chromatography. Suc- cessive elution with hexanes (hex)-ethyl acetate (EtOAc) (100:0, 90:10, 70:30, 30:70, 50:50 and 0:100, v/v) and finally washing with methanol gave four fractions (A-D) with the masses of 10.0 g, 6.84 g, 1.96 g and 3.25 g, respectively. Thin-layer chromatography (TLC) was used to monitor the chemical composition of the fractions and TLC was used to choose the suitable solvent system for further purification by silica gel column chromatography. Fraction B was further separated by column chromatography using EtOAc-hex (60:40, v/v) to afford four fractions (B1 - B4). Purification of fraction B2 by column chromatography using DCM-MeOH (95:5, v/v) yiel- ded seven fractions (B2.1 - B2.7). Further purification of fraction B2.3 using EtOAc-hex (60:40, v/v) afforded compound 1 (14 mg). Separation of fraction B2.4 eluting with EtOAc-hex (50:50, v/v) resulted in the isolation of compounds 2 (2 mg) and 4 (5 mg). Attempted dissolution of fractions B2.5 and B2.6 in methanol yielded a light yellow precipitate of compound 3 (12 mg). Fraction A (10 g) was separated by column chromatography using hex-EtOAc (70:30, v/v) to give five fractions (A1 - A5). Purification of fraction * Corresponding author. E-mail address: vanheerdenf@ukzn.ac.za (F.R. van Heerden). Contents lists available at ScienceDirect Biochemical Systematics and Ecology journal homepage: www.elsevier.com/locate/biochemsyseco https://doi.org/10.1016/j.bse.2017.10.002 0305-1978/© 2017 Elsevier Ltd. All rights reserved. Biochemical Systematics and Ecology 75 (2017) 18e20