J.D. Gbenou, M. Moudachirou, Jean-Claude Chalchat* and Gilles Figuérédo

Abstract: Forty compounds have been characterized by GC and GC/MS and relative retention times in 300 samples of Niaouli (Melaleuca quinquenervia) oils collected on 75 different trees during four seasons. Twenty-one compounds were submitted to multivariate statistical analyses using Principal Component Analysis (PCA). Factorial Discriminant Analysis (FDA) revealed the presence of three chemotypes. Chemotype I is already known (1,8-cineole; 50%), chemotype II had an equal content in 1,8-cineole (33%) and viridiflorol (32%). The third (chemotype III) was characterized by a high content in viridiflorol (50%). The 1,8-cineole chemotype represented 58% of three populations. Seasonal differentiation does not occur, showing that Niaouli oil composition is stable all year.

To ascertain the occurrence of various chemotypes and seasonal influence on the main components in Niaouli essential oil from Benin, the change in chemical composition was followed at four seasons of the year: Great Rain Season (GRS), Small Dry Season (SDS), Small Rain Season (SRS) and Great Dry Season (GDS). Chemotypes were identified using chemical compound content. Multivariate statistical analyses were applied to 300 essential oil samples (1). Australia and Pacific are countries from which Melaleuca species originate. Many authors have reported on (2–5). Several studies of Melaleuca species from different countries was reported (6–18 ; 25,26). Several chemotypes were identified in different species and they were characterized by high levels of 1,8-cineole (40–50%) (6–10), (E)-nerolidol (40–80%) (7,11), (E) methyl isoeugenol (> 80%) or methyl eugenol (99%) (12) and two viridiflorol types, the first (48%) from Madagascar (7), the second (> 40%) from Benin (6). Niaouli oil may affect microbial growth, since the oils are characterized by possessing pharmaceutical and antimicrobial properties (11,13).