Isolation of two cassane-type diterpenoids from the bark of Erythrophleum suaveolens (Guill. & Perr.) Brenan (Fabaceae)

*Corresponding author: Ouattara Logopho Hyacinthe Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Isolation of two cassane-type diterpenoids from the bark of Erythrophleum suaveolens (Guill. & Perr.) Brenan (Fabaceae) Logopho Hyacinthe Ouattara 1, *, Richmond Jean-François Kablan 1, Aminata Akoubet-Ouayogode 2, Dibi Jacques Konan 3, Ahmont Landry Claude Kablan 1, N’dri Marcelline Adiko 2 and Obiang Cédric Sima 4 1 UPR Chemistry, Department of Mathematics-Physics-Chemistry, Faculty of Biological Sciences, Peleforo GON COULIBALY University, BP 1328 Korhogo, Ivory Coast 2 Laboratory of Medicinal Sciences, Analytical Sciences, and Public Health, Department of Pharmaceutical Sciences, UFR SPB, Félix Houphouët-Boigny University, Cocody (Ivory Coast) 3 Laboratory of Bio-Organic Chemistry and Natural Substances (LCBOSN), UFR-SFA, NANGUI ABROGOUA University, 02 BP 801 Abidjan 02, Ivory Coast 4 Laboratory for Research in Biochemistry (LAREBIO), Faculty of Sciences, Masuku University of Science and Technology, Franceville, Gabon. GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 Publication history: Received on 21 August 2025; revised on 27 September 2025; accepted on 30 September 2025 Article DOI: https://doi.org/10.30574/gscbps.2025.32.3.0376 Abstract Erythrophleum suaveolens is a plant species used to treat Buruli ulcer in Côte d'Ivoire. This plant is rich in cassane-type diterpenoids, compounds known for their multiple biological activities. This study focuses on the isolation, purification, and structural identification of two cassane-type diterpenoids from the ethyl acetate extract of the bark of Erythrophleum suaveolens. Two molecules were isolated using conventional purification and isolation methods, namely column chromatography and preparative HPLC. The structural analysis of these compounds was carried out using onedimensional (1D) and two-dimensional (2D) 1H and 13C Nuclear Magnetic Resonance (NMR), COSY, HMBC, and NOESY. The molecules were identified as 3β-acetoxyerythrosuamine and 3β-hydroxy-3-methylbutanoyloxy-6α-hydroxy-norcassamine. These compounds have already been isolated from the root bark of this plant, but this is the first time they have been isolated from the trunk bark. Both compounds belong to the cassane genus, and their discovery enriches the chemistry of E. suaveolens. Keywords: Fabaceae; Erythrophleum suaveolens; Cassane diterpenoid; NMR 1. Introduction Cassane-type diterpenoids are an important class of secondary metabolites in several species of the genus Erythrophleum as well as in other Fabaceae. In the genus Erythrophleum, despite their high toxicity to humans and livestock, many species are widely used for therapeutic purposes in various local communities [1]. In addition, in Africa and Asia, traditional medicine practitioners empirically used decoctions of leaves or powdered bark from species of the genus Erythrphleum to treat various conditions, including cardiovascular disease, dysentery, and diarrhea (decoction of E. africanum leaves) [2, 3], blood cancer and mental illness (aqueous extract of leaves and trunk bark of E. africanum, aqueous extract of leaves of E. fordii) [4, 5], lung diseases in livestock (powder from the bark of E. chlorostachys) [6], smallpox, convulsive disorders, pain, swelling (bark of E. ivorense) [7, 8], fevers (powder from the bark of E. chlorostachys) [6]. The powdered bark of E. couminga is used as a purgative and laxative. It was previously used as a poison for fishing and hunting. Pharmaceutical companies used the bark of E. couminga as a non-steroidal cardioactive drug, but the project was abandoned due to a shortage of material [9]. GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 315 Species of the genus also have various biological activities: cytotoxicity, antimalarial, antioxidant, and anti-inflammatory [10, 11, 12, 13]. Erythrophleum suaveolens, a tree widespread in West Africa, is used in traditional medicine [14]. The objective of this study is to isolate cassane-type diterpenoids from the bark of Erythrophleum suaveolens. These molecules will enrich the knowledge base on cassane diterpenoids in this species and may serve as a basis for further pharmacological investigations. 2. Material and methods 2.1. Material 2.1.1. Plant material The bark of the trunk of Erythrophleum suaveolens (Guill. & Perr.) Brenan (Fabaceae) was collected in December in Toumodi (Pacobo: 6°09'56.8“N 4°56'26.1”W), a town located in central Côte d'Ivoire. It was identified and authenticated at the National Floristic Center (CNF) of Félix HOUPHOUËT-BOIGNY University (Abidjan, Ivory Coast). A specimen numbered 10 DIBI ES-2014 was deposited in the herbarium of this center. The bark was scraped from the trunk using a machete, dried in the laboratory away from sunlight, and ground using an electric grinder. The powder obtained was used for the extractions. 2.1.2. Chemical material The chemical materials consist of distilled methanol, ammonium hydroxide, dichloromethane, sulfuric acid, distilled ethyl acetate, formic acid, acetonitrile, Sephadex® LH 20, and silica gel 60. 2.2. Methods 2.2.1. Extraction 1 kg of E. suaveolens bark powder was subjected to solid-liquid extraction at room temperature in 10 L of distilled methanol (MeOH) for 24 hours. This operation was repeated twice more with the residual marc under the same conditions as before. After filtration, the various solutions were evaporated using a rotary evaporator (Ratavapor, Sartorius Stedim Biotech) and then dried to yield 48.3 g of crude extract. Next, 15 g of this methanolic extract was dissolved in 50 mL of MeOH, then alkalized with a few drops of 25% ammonium hydroxide (NH4OH), and then supplemented with 100 mL of dichloromethane (CH2C12). To the solution obtained, 100 mL of 1% sulfuric acid was added. The solution obtained was counter-extracted by liquid-liquid extraction with distilled CH2C12 (100 mL x 4). The supernatant phase separated from the dichloromethane phase is first alkalized with NH4OH to pH = 10, then counterextracted with distilled ethyl acetate (100 mL x 4) to give, after evaporation using a rotary evaporator, the ethyl acetate extract coded ESA. 2.2.2. Preliminary test: phytochemical screening The ESA extract underwent phytochemical screening with Dragendorff's reagent. The test proved positive, so the ESA extract was used for fractionation and purification. 2.2.3. Chromatographic methods Thin-layer chromatography (TLC) Thin-layer chromatography analyses were performed on aluminum plates (Silicagel 60 F254, Merck, Germany). After development in glass tanks, the plates were observed under ultraviolet light (254 nm and 366 nm). The UV lamp used was manufactured by Vilber Lourmat (230 V, 50 Hz, France). Flash chromatography We used a device with an isocratic and gradient pumping system, with a double piston pump. Cartridges weighing 330 g, 120 g, and 24 g from the Grace Resolv® Silica Flash Silica series were used. These cartridges have the advantage of effectively replacing glass columns. GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 316 Silica gel column chromatography (CC) Chromatographic column separations were performed taking into account the mass of the sample (fraction or extract) to be fractionated and its chromatographic profile (CCM). The diameter and height of the column are determined based on the mass of the sample. For effective separation, the mass of silica in the column is equal to 10 times the mass of the sample to be purified [15]. In this study, the stationary phase used in the various CCM separations was silica gel 60 (4063 µm, Chromagel, Merck). Fractionation and purification of ESA extract constituents The ESA extract is initially purified using flash chromatography. For 2 g of ESA extract, a cartridge containing 10 g of silica gel 60 was used. The elution system consists of a MeOH/ CH2Cl2 mixture following an elution gradient of 1:99 (v/v) to 50:50 (v/v). The fractions collected are grouped according to their chromatographic profiles (CCM). A total of 6 fractions (F1 to F6) were collected, and each fraction was then purified on a chromatographic column using a 1.5 cm diameter column and Sephadex® LH 20 as the stationary phase. Fractions F1 to F5 were purified under the same conditions, using a CH2Cl2/MeOH (2:1, v/v) mixture as eluent, following isocratic elution, to give a single subfraction. This fraction was then purified by preparative high-performance liquid chromatography (HPLC) using the H2O+0.1% methanoic acid (HCOOH)/acetonitrile (ACN) system (85:15 to 50:50, v/v) to provide compound 1. Fraction F6 is purified under the same conditions as F1-F5, using the CH2Cl2/MeOH (1:1, v/v) mixture as eluent, following isocratic elution, to give a single subfraction which is then purified by preparative HPLC (reverse phase) with the H2O+0.1% HCOOH/ ACN (85:15 to 50:50, v/v) to give compound 2. 2.2.4. Structural identification The isolated compounds were subjected to the following spectroscopic techniques: • 1H and 13C NMR to assign proton and carbon signals. • Two-dimensional experiments: o COSY (Correlation Spectroscopy) to identify couplings between adjacent protons. o HMBC (Heteronuclear Multiple Bond Correlation) for long-range proton-carbon correlations (2-3 bonds) to locate substituents and side chains. o NOESY to establish spatial proximities (interactions across space), which helps define relative stereochemistry (α/β faces, 3β, 6α positions, etc.). • Other spectral data (exact mass, IR) as needed to confirm functional groups (hydroxyl, ester, acetoxy) and molecular formula. For purity control, each purified compound was checked by thin-layer chromatography (TLC) for homogeneity, and by additional spectra to ensure that there was no mixture. 3. Results 3.1. Structural elucidation of compound 1 Compound 1, soluble in methanol, was obtained as an amorphous solid. Its IR spectrum shows certain characteristic bands, such as those at ʋmax 1735, 1721, and 1594 cm-1, which indicate the presence of three ester functions, and the band at ʋmax 1669 cm-1, which suggests the presence of a ketone function. The hydroxyl and amine groups give broad absorption bands centered at ʋmax 3342 and 3323 cm-1. The mass of this compound was determined using the HRESIQTOF-SM+ method. The HRESI-QTOF-SM+ mass spectrum shows the peak of the pseudomolecular ion [M+H]+ at m/z 494.2713, corresponding to a molecular mass of 493.2635 g/mol. This value is consistent with the molecular formula C26H39NO8 (calculated mass 493.2676). The fragmentation pattern of this molecule is typical of diterpenoid cassanes and resembles those of 3β-hydroxy-3-methyl-butanoyloxy)-nor-erythrosuamine and 3β-hydroxy-3-methylbutanoyloxy-6α-hydroxy-nor-cassamine [11]. The difference with these compounds is the loss of the acetate fragment (CH3-COO-; m/z 59 g/mol) in the form of acetic acid (CH3-COOH) observed at m/z 60 g/mol. The 1H and 13C NMR spectra of compound 1, performed in deuterated methanol, confirm the link between this compound and those of 3β-hydroxy3-methyl-butanoyloxy)-nor-erythrosuamine and 3β-hydroxy-3-methyl-butanoyloxy-6α-hydroxy-nor-cassamine [11]. Indeed, there is a very strong resemblance between the spectra of these three molecules. However, on the proton spectrum of compound 1, a singlet is observed at H 2.00 ppm, whereas on those of 3β-hydroxy-3-methyl-butanoyloxy)- GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 317 nor-erythrosuamine and 3β-hydroxy-3-methyl-butanoyloxy-6α-hydroxy-nor-cassamine, this singlet resonates at H 2.49 (s, 2H) and 2.45 (s, 2H) ppm, respectively. The HSQC spectrum indicates that the proton at H 2.00 ppm (s, 3H) is carried by the carbon at δC 20.8 ppm. Also, the HMBC spectrum data allowed the acetoxy group (CH3COO) to be fixed in the C-3 position on the carbon chain. Indeed, the carbon at δC 172.1 ppm (C=O) correlates in 2JCH with the proton at H 2.00 ppm, and in 3JCH with the proton at H 4.72 ppm (HC-OH; C-3). We also observe correlations in 3JCH between the carbon at δC 77.0 ppm (HC-OH) and the protons at H 1.96 ppm (H-9) and 2.81 ppm (H-14). We can therefore deduce that the secondary alcohol at δC 77.0 ppm is in position C-7. The carbon of the ketone function observed at δC 209.6 ppm (C=O, ketone) correlates in 2JCH with the protons at δH 2.75 ppm (H-5) and H 4.05 ppm (H-7). We can also deduce that the ketone function is in position C-6. According to the NOESY spectrum, the proton in position (H-7) sees protons H-3, H-5, H-9, and H-18, which are behind the plane. Comparing our spectra with those of this compound allowed us to identify compound 1 as 3β-acetoxyerythrosuamine (Figure 1). Table I provides information on 1H and 13C NMR chemical shifts, COSY, NOESY, and HMBC correlations. Table 1 1H and 13C NMR chemical shift (1D and 2D) of compound 1 (MeOD) N° atom 13C (δ, ppm) 1H (δ, ppm ; m ; J, Hz) COSY HMBC NOESY 1 37,2 1,51 ; 1H ; m 1,85 ; 1H ; m H-2α H-2β C-3 ; C-9 ; C-20 - - - 2 24,9 1,69; 1H; m 2,21 ; 1H ; m H-1α ; H-3α H-1β ; H-3β - - - - 3 80,3 4,72 ; 1H ; dd (12,4 ;3,03) H-2α C-1 ; C-19 ; C25 - 4 43,3 - - - - 5 65,0 2,75 ; 1H ; s - C-6; C9, C-19; C18 C-20 H-18 6 209,6 - - - - 7 77,0 4,05 ; 1H ; d (11,4) - C-8; C14, C-6 H-17 8 52,1 1,84 ; 1H ; m H-9 - H-20 9 47,1 1,96 ; 1H ; m H-8 C-20 - 10 37,2 - - - - 11 27,7 1,12 ; 1H ; m 1,93 ; 1H ; m H-12α H-12β - C-12; C13 - - 12 24,8 2,11 ; 1H ; m 3,31 ; 1H ; m H-11α H-11β C-11; C-15 C-16 - - 13 167,4 - - - - 14 41,9 2,81 ; 1H ; m H-17 C-8; C-15 H-15 15 113,1 5,81 ; 1H ; s - C-12; C-13; C-16 H-14 16 169,7 - - - - 17 14,9 1,21 ; 3H ; d (6,8) H-14 C-8; C-13 H-7 18 25,7 1,18 ; 3H; s - C-19; C-5; C-5; C-10 H-5 19 174,8 - - - - 20 14,9 0,96; 3H; s - C-1; C-5; C-9; C-10 H-8 21 60,2 4,33 ; 2H ; m H-22 C-16 - 22 49,6 3,28 ; 2H ; m H-21 C-23 - 23 33,8 2,71 ; 3H ; s - C-21 - GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 318 24 52,0 3,70 ; 3H ; s - C-19 - 26 172,1 - - - - 26 20,8 2,00 ; 3H ; s - C-25 - Figure 1 Structure of 3β-acétoxyérythrosuamine 3.2. Structural elucidation of compound 2 Compound 2 was obtained as an amorphous solid, soluble in methanol. Its IR spectrum also indicates the presence of carbonyl groups (ester, ketone, and amide) as evidenced by absorption bands observed at ʋmax 3343, 3321, 1733, 1713, 1706, and 1670 cm⁻¹. The molecular mass of this compound was determined using high-resolution electrospray ionization in positive mode (HRESI-QTOF-SM+). The HRESI-QTOF-SM+ mass spectrum shows the pseudo-molecular ion [M+H]+ peak at m/z 552.3177, giving a molecular mass of 551.3099 g/mol. This value corresponds to the molecular formula C29H45NO9 (calculated mass 551.3094). The fragmentation pattern of compound 2 suggests that it is a cassane-type diterpenoid [16]. Some fragments are also comparable to those of 6α-hydroxy-norcassamine [17]. Specifically, the ion [(M+H)-75]+ observed at m/z 478.2111 corresponds to the loss of HO-CH2-CH2-NHCH3; the ion [(M+H)-75-118]+ observed at 360.1566 corresponds to the loss of HO-CH2-CH2-NHCH3; the ion [(M+H)-75-118-60]+ observed at 300.1415 corresponds to the loss of CH3O-CO; and the ion [(M+H)-31]+ observed at m/z 522.2316 corresponds to the loss of CH3-NH2 (Figure 2). Figure 2 ESI-MS/MS mass spectrum of 3β-hydroxy-3-methyl-butanoyloxy-6α-hydroxy-nor-cassamine GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 319 The fragment that differentiates 6α-hydroxy-norcassamine from compound 2 is the 3-hydroxy-3-methylbutanoate group (HO-C(CH3)2-CH2-COO-), which captures a proton to form 3-hydroxy-3-methylbutanoic acid (Figure 3), corresponding to the loss of a mass unit of 118 g/mol. Figure 3 Conversion of the 3-hydroxy-3-methylbutanoate ion to 3-hydroxy-3-methylbutanoic acid The positioning of the 3-hydroxy-3-methylbutanoate group on the carbon skeleton of compound 2 was determined based on correlations observed in the HMBC spectrum. In this spectrum, the carbonyl at δC 172.5 ppm shows a 3JCH correlation with the proton at δH 4.64 ppm (H-3), allowing it to be assigned to carbon C-3 of the basic cassane-type diterpenoid skeleton. Regarding the stereochemical arrangement of this molecule, the NOESY spectrum shows that the H-3 proton is positioned behind the plane, as it correlates with H-5, H-9, H-17, and H-18, which are also behind the plane. From this, it is deduced that the 3-hydroxy-3-methylbutanoic acid group (Figure 3) is oriented in front of the molecular plane. Based on the analyses above, compound 2 was formally identified as 3β-hydroxy-3methylbutanoyloxy-6α-hydroxy-nor-cassamine (Figure 4). This molecule has previously been isolated from the root bark of Erythrophleum suaveolens [18]; however, this is the first time it has been identified in the trunk bark of this plant. Figure 4 Structure de la 3β-hydroxy-3-méthyl-butanoyloxy-6α-hydroxy-nor-cassamine We have thus proposed a fragmentation scheme with the major fragments observed at m/z 553.3247, 522.2316, 478.2111, 360.1566, and 300.1415 (Figure 5). GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 320 Figure 5 Fragmentation pattern of 3β-hydroxy-3-methyl-butanoyloxy-6α-hydroxy-nor-cassamine 4. Discussion The structures isolated in this study, namely 3β-acetoxy-erythrosuamine and 3β-hydroxy-3-methylbutanoyloxy-6αhydroxy-nor-cassamine, are cassane-type diterpenoids with an amine function. Both molecules have previously been reported from the root bark of E. suaveolens. Several cassane-type diterpenoids with an amine function, such as 6αhydroxy-nor-cassamine or 8,9-dehydro-nor-cassamine [1], show similarities with compound 2 isolated in this study (3βhydroxy-3-methylbutanoyloxy-6α-hydroxy-nor-cassamine), particularly regarding the nor-cassamine skeleton. Likewise, the work of Konan et al. [11] reported new cassane-type amine derivatives bearing “3-hydroxy-3methylbutanoyloxy” groups, which further links compound 2 from our study to these cases. Although numerous cassane diterpenoids have been described, these two compounds exhibit particular substitutions: an acetoxy group in the first case, and a 3-methylbutanoyloxy group plus a 6α-hydroxy group in the second. These modifications can strongly influence polarity, chemical stability, and potentially biological properties (affinity, activity, toxicity). These compounds could be good candidates for biological activity studies (antioxidant, anti-inflammatory, cytotoxic). Indeed, some cassane-type diterpenoids with amide or hydroxyl functions from E. suaveolens reported by Konan et al. [11] have shown significant antioxidant capacities. It would be interesting to evaluate the compounds isolated in this study in similar tests, or others, to assess the influence of these specific substitutions (acetoxy vs. hydroxy + bulky ester) on activity. 5. Conclusion This study allowed the isolation from the trunk bark of Erythrophleum suaveolens of two cassane-type diterpenoids newly characterized in the context of trunk bark: 3β-acetoxy-erythrosuamine and 3β-hydroxy-3-methylbutanoyloxy6α-hydroxy-nor-cassamine. These molecules enrich the chemical repertoire of the species, particularly regarding esterified and hydroxylated substituents. Their discovery paves the way for future biological investigations to explore GSC Biological and Pharmaceutical Sciences, 2025, 32(03), 314-321 321 their pharmacological potential. For future studies, it is recommended to evaluate their biological activity and, if possible, to synthesize derivatives to establish structure-activity relationships. Compliance with ethical standards Disclosure of conflict of interest Authors declare that there are no conflicts of interest. References [1] Dade J.M.E., Kablan L.A., Okpekon T.A., Say M., Yapo K.D., Komlaga G., Boti J.B., Koffi A.P., Guei L.E., Djakoure L.A., Champy P. (2015). Cassane diterpenoids from stem bark of Erythrophleum suaveolens [(Guill. et Perr.), Brenan]. Phytochemistry Letters.;12:224-231. DOI:10.1016/j.phytol.2015.04.002 [2] Jinju M.H., (1990). A case study of Hausa Medicinal Plants and Therapy.Gaskiya Corpn. Ltd. Zaria. Nigeria. Afr. Trad. Med., 43-50. [3] Dalziel JM., (1999). Useful plants of tropical West Africa. Crown Agents London. 432-434. [4] Fang Y., Nan L., Shi-Shan Y. (2003). A new diterpenoid glucopyranoside from Erythrophleum fordii, Journal of Asian Nat. Prod. Res. 7(1), 19-24 [5] Yu F., Li N., Yu S.S. (2005). A new diterpenoid glucopyranoside from Erythrophleum fordii. J. Asian Nat. Prod. Res., 7(1), 19-24. [6] Hutchings A., Scott A.H, Lewis G., Cunningham A. (1996). Zulu Medicinal Plants: An Inventory. Pietermaritzburg, South Africa: University of Natal Press, p32 [7] Cronlund A. (1973). Two new alkaloids from the bark of Erythrophleum ivoirense. Acta Pharm. Suec.10, 507-514. [8] Irvine F.R. (1961). Woody Plants of Ghana. Oxford University Press, Amen House, London, p 7. [9] Boiteau P., Potier P. (1974). La prospection des plantes médicinales. Le Courrier du CNRS, n°14, 19-23. [10] Armah F.A., Annan K., Mensah A.Y., Amponsah I.K., Tocher D.A., Habtemariam S. (2015). Erythroivorensin: A novel anti-inflammatory diterpene from the root-bark of Erythrophleum ivorense (A Chev). Fitoterapia, 105, 3742. [11] Konan J.D., Attioua K.B., Kabran F.A., Ahmont Kablan C.L., Koffi A.A., Any-Grah S.A., Sissouma D., Seon-Meniel B., LeBlanc K., Jullian J.C., Beniddir M.A., Champy P. (2019a). New cassane diterpenoids from the root bark of Erythrophleum suaveolens. Phytochem. Lett.;31:166-169. DOI:10.1016/j.phytol.2019.07.007 [12] Kablan A.C.L., Jacques D.K., Gustav K., Faustin A.K., Ballo D., Amon D.N., Tapé K., Adrien J., Karine L., Blandine S.- M., Mehdi A.B., Koffi B.A., Pierre L.P., Pierre Champy (2020). Five new cassane diterpenes from the seeds and bark of Erythrophleum suaveolens, Fitoterapia, Volume 146, 104700, https://doi.org/10.1016/j.fitote.2020.104700. . [13] Son N.T. (2019). Genus Erythrophleum: Botanical description, traditional use, phytochemistry and pharmacology. Phytochem Rev 18, 571–599 (2019). https://doi.org/10.1007/s11101-019-09640-0 [14] Yemoa A.L., Gbenou J.D., Johnson R.C. (2008). Identification et étude phytochimique de plantes utilisées dans le traitement traditionnel de l’ulcère de Buruli au Bénin. Ethnopharmacologia, 42, 48-55. [15] Vernin, G. (1970). La chromatographie en couche mince : Techniques et applications en chimie organique, Paris : Dunod. XI + 177 pages. [16] Qu J., Wang Y-H., Li J-B., Yu S-S., Li Y., Liu Y-B. (2007). Rapid structural determination of the new cassaine-type diterpenoid amides in fractions from Erythrophleum fordii by liquid chromatography-diode-array detection/electrospray ionizaton tandem mass spectrometry and liquid chromatography/nuclear magnetic resonance. Rapid comm. Mass Spectrom., 2007, 21, 2109-2119. [17] Konan J.D., Kabran F.A., Attioua B.K., Kablan A.LC., Aka A-G.S., Koffi A.A., Akoubet O., Otogo N.E., Seon-Meniel B., Le Blanc K., Jullian J-C., Sissouma D., Beniddir M.B., Champy P. (2019b). Three novel non-nitrogenous cassane diterpenoids from Erythrophleum suaveolens (Guill. et Perr.) Brenan (Fabaceae). Natural Product Research,; DOI: 10.1080/14786419.2019.1650354; https://doi.org/10.1080/14786419.2019.1650354. [18] Konan J.D., Attioua B.K., Kabran A.F., Kablan A.LC., Koffi A.A., Aka Any-Grah S., Sissouma D., Seon-Meniel B., Karine L., Jullian J-C., Beniddir M.A., Champy P. (2019c). Spectroscopic data of new cassane diterpenoids from the root bark of Erythrophleum suaveolens. Data in brief, 2019c, 25, 104315.