Phenolics, alkaloids, saponins and cyanogenic glycosides.pdf

1226 S. Mali, R.M. Borges / Biochemical Systematics and Ecology 31 (2003) 1221–1246in almost all cases, we were examining only one species per genus, and one genusper family.3. Results3.1. Occurrence of alkaloids, saponins, cyanogenic glycosides and phenolicsCyanogenic glycosides were not found in any of the plant tissues examined (N= 54 bark items, N = 108 reproductive parts, N = 109 leaf items) except for theflush leaves of B. retusa (Euphorbiaceae). Therefore, only one out of 43 plant species(2.3%) exhibited cyanogenesis. Summaries of the species-wise occurrence of thedifferent compounds in the various plant parts are given in Table 2. Alkaloids werenot found in petioles, semi-ripe and ripe fruit, and mature seeds examined (AppendixA, Table A1). Saponins were found in all types of plant parts (Appendix A, TableA1). Condensed tannins were found in all immature leaves, as well as all petiolesand flowers examined. Hydrolysable tannins were found in 68% of species, and 38%of plant samples. Gallotannins were found in only 31% of the samples examinedwhile ellagitannins were found in still fewer samples (only 19%). Fewer plant speciescontained condensed or hydrolysable tannins in their bark and stems than in otherplant parts.3.2. Relative concentrations of secondary compounds in plant partsImmature leaves, flowers, and petioles had high astringency while lower levelswere found in fruit (Table 3). Tree twigs had low levels of astringency, condensedand hydrolysable tannins but high levels of fibre (Table 3). Inner bark had astringencyand condensed tannin levels comparable to that of mature leaves while fibre levelswere lower than those found in twigs (Table 3). Flowers and fruit had low fibrelevels (Table 3). After Bonferroni’s correction (P 0.001), only immature leaveswere found to have significantly higher astringency, gallotannin and ellagitannin contentthan tree twigs, flowers were found to have significantly higher gallotannin levelsthan immature leaves, and tree twigs were found to have significantly higher ADFlevels than mature seeds.3.3. The quantitative relationship between various measures of phenolicsAstringency levels were strongly positively correlated with total phenolic, condensedtannin, gallotannin and ellagitanin contents (Table 4). Condensed tanninvalues were not correlated with gallotannin or ellagitannin contents. Gallotannin andellagitannin contents were strongly positively correlated with each other (Table 4).Of the fibre components, since ADF, NDF and ADL are all highly correlated witheach other, we used only ADF values in the correlations. We found no significantrelation between any measure of phenolics and fibre after Bonferroni’s correction,except for the negative relationship between gallotannins and ADF (Table 4).