Akinola O. Ogunbinu, Isiaka A. Ogunwande,* Emmanuel Essien, Pier L. Cioni and Guido Flamini
Abstract: The essential oils of the leaf and stem bark of Polyalthia longifolia Thw. (Annonaceae) have been studied for their
constituents by means of GC and GC/MS. The leaf oil was almost exclusively composed of sesquiterpene derivatives,
being represented by allo-aromadendrene (19.7%), caryophyllene oxide (14.4%), β-caryophyllene (13.0%), β-selinene
(7.9%), α-humulene (7.0%) and ar-curcumene (6.8%). However, α-copaene and α-muurolol (ca. 8.7%), β-selinene
(8.6%), viridiflorene (8.1%), α-guaiene (7.8%), allo-aromadendrene (7.4%) and δ-cadinene (7.0%) were the major
constituents occurring in the oil of the bark sample. All the other sesquiterpenoid compounds were observed in
amount greater than 1%. α-Pinene (0.5%) and camphene (tr), which are the two monoterpenoids present in the leaf
oil, could not be detected from the bark essential oil.
As a continuation of our research about the volatile oils of poorly studied species of Nigerian flora (1), we report here the constituents identified from the leaf and bark of Polyalthia longifolia Thw (Annonaceae). About 120 species of Polyalthia are distributed throughout the tropics. Polyalthia longifolia is a tall, handsome, evergreen tree cultivated in gardens in Southwestern Nigeria. In Nigeria and elsewhere, the plant is used for the treatment of skin diseases, fever, diabetes and hypertension. A number of biologically active compounds have been isolated from the non-volatile fractions of the plant. A phytochemical study on the hexane extract of the stem bark of P. longifolia has led to the characterization of clerodane and ent-halimane diterpenes (2,3), two of which have demonstrated significant antibacterial and antifungal activities (4). Previous studies on the oil of the plant reports on the antimicrobial activity of the essential oils (5–9). Another paper also reports on a preliminary investigation of the essential oil of the leaves, in which azulene derivatives were detected (10).
