Within-tree variability of chemical constituents of Tessmaniaafricana from Gabon

This work studies the intra-tree variability of the chemical constituents of Tessmania africana from Gabon from two trees, at three height levels (DBH, mid-height and under the crown) and two radial positions (sapwood and heartwood). The contents of ethanol-toluene and hot water extracts in tree 1 gave 10.1% (heartwood) and 7.5% (sapwood), and in tree 2; 9.8% (heartwood) and 5.7% (sapwood). The cellulose content is 46.8% (heartwood) against 46.3% (sapwood) for tree 1 and 47.6% (heartwood) and 47.2% (sapwood) for tree 2; with very little variation from tree to tree. The hemicelluloses (pentosanes) gave an average content of 17.1% (heartwood) against 19.4% (sapwood) for tree 1 and 17.4% (heartwood) and 19.0% (sapwood) for the tree 2. The total lignin content in tree 1 is 28.3% (heartwood) and 28.2% (sapwood) and for tree 2; 28.1% (heartwood) and 27.8% (sapwood). Total phenols, flavonoids, hydroxycinnamic acids, proanthocyanidins or condensed tannins are determined by UV-visible spectroscopy. In tree 1, total phenols vary from 248 to 434 mg gallic acid equivalents/g of dry extract and are more abundant in the heartwood, particularly at mid-height. For tree 2, the total phenols are also concentrated in the heartwood, 397 mg gallic acid equivalents/g of dry extract. The content of hydroxycinnamic acids varies between 112.6 and 193.1 mg of chlorogenic acid equivalent/g of dry extract in the heartwood against 82.0 and 153.5 mg of chlorogenic acid equivalent/g of dry extract in the sapwood for tree 1, and values varying from 103.5 and 166.8 mg of chlorogenic acid equivalent/g of dry extracts for the heartwood and 81.4 and 179.2 mg of chlorogenic acid equivalent/g of dry extracts in the sapwood for tree 2. The hydroxycinnamic acids indicate a higher concentration in the heartwood than in the sapwood and maximum values at mid-height in the sapwood for the two trees. Proanthocyanidins vary between 6.3 and 74.8 mg cyanidin chloride equivalent/g dry extract in sapwood and 43.6 and 93.6 mg cyanidin chloride equivalent/g extract dryness in the heartwood for tree 1 and values varying between 17.6 and 44.8 in mg of cyanidin chloride equivalent/g of dry extract in the sapwood; 17.6 and 68.0 in mg of cyanidin chloride equivalent/g of dry extract in the heartwood for tree 2. Tessmania africana is a tropical species rich in phenolic compounds which are more concentrated in the heartwood and in the mid- height.