Chemical characterisation of six wood species from Côte d’Ivoire: macromolecular composition, extractives yields and profiling by GC-MS and FTIR

Abstract

This study aimed to characterise extracts from six tropical hardwoods of Cote d’Ivoire, notably Milicia excelsa (iroko), Khaya ivorensis (mahogany), Triplochiton scleroxylon (samba), Gmelina arborea (gmelina), Piptadeniastrum africanum (dabema), and Acacia mangium (acacia), through macromolecular quantification, FTIR, and GC–MS analyses. The objectives were to evaluate solvent-dependent extraction yields, to identify and classify major groups of extractives, to assess polysaccharide and lignin composition across species, and to highlight metabolites of industrial and biological significance, including those reported here for the first time. Extraction yields varied markedly among species. Gmelina arborea (gmelina) displayed the highest levels, exceeding 10%, particularly in dichloromethane fractions rich in polar compounds. Iroko and mahogany showed intermediate yields between 6 and 8%, enriched in phenolic fractions, while dabema, acacia, and samba produced lower amounts. FTIR spectra revealed characteristic hydroxyl, carbonyl, and aromatic absorptions, in agreement with the chemical families confirmed by GC–MS. This analysis identified a wide diversity of metabolites, such as chlorophorin, catechin, resveratrol, lupeol, gmelinol, and major fatty acids, including palmitic and stearic acids. Notably, gmelinol in Gmelina arborea and oxyresveratrol in iroko are reported here for the first time in Ivorian hardwoods. In addition, the polysaccharide and lignin contents varied considerably among species. Cellulose ranged from 29.65% in iroko to 42.01% in acacia, holocellulose extended from 69.33% in dabema to 74.69% in acacia, and lignin fluctuated between 21.54% in acacia and 28.49% in gmelina. These variations reflect interspecific differences in wood structure and may partly account for the diversity of extractive profiles and durability. Overall, the results highlight the significant bioactive potential of Ivorian hardwoods and support the valorisation of sawmill by-products as sustainablesources of high value-added compounds.