Phenolic compounds and radical scavenging potential of twenty Cameroonian spices

Abstract

The antioxidant activity and phenolic content of twenty different spices commonly used in Cameroon were analyzed with the view of updating our present knowledge on their nutritional and nutraceutical potentials. To achieve this aim, the ferric iron reducing activity (FIRA), hydroxyl radical scavenging activity (HRSA), free radical scavenging activity (FRSA), total phenols, flavonoids, proanthocyanidins, and tannins content were analyzed using current techniques. In all the cases significant variations (p<0.001) were observed in the levels of the parameters analyzed. The different parameters varied as follows: total phenols (1.05 – 38.80 g/100 g), flavonoids (0.00 g – 5.94 g/100 g), tannins (0.00 – 281.5 mg/100 g), FIRA (1.55 – 168.63 mg/100 g), FRSA (3.96 – 71.5 mg/g), HRSA (0.01 – 2.45 mg/100 g). Using Principal Component Analysis (PCA), 79 % of the variation in spices was found to be mainly associated with their FRSA, FIRA, total phenols, flavonoids, and proanthocyanidins content. Furthermore, using K-means classification, it was possible to classify the spices into four major groups, each of relatively similar composition as follows: Group 1 has high FRSA and FIRA levels, high phenols, and flavonoids contents: Dichrostachys glomerata, Fagara leprieuri; Group 2 has high HRSA levels: Fagara xanthoxyloides, Mondia whitei, Pentadiplandra brazzeana, Piper guineense, Scorodophleus zenkeri (fruit), Scorodophleus zenkeri (bark); Group 3 has low levels in all variables: Aframomum daniellii, Hua gabonii (fruit), Monodora myristica, Dorstenia psilurus, Hua gabonii (bark), Piper umbellatum, Solanum melongena, Scleria striatinux, Xylopia aethiopica and Group 4 has moderate levels of FRSA and FIRA, phenols, flavonoids and proanthocyanidins: Echinops giganteus and Tetrapleura tetraptera. In addition Pearson correlation analysis revealed strong positive correlations between FRSA and FIRA (93 %), between FRSA and total phenols (90 %) and between flavonoids and total phenols (93 %). Dichrostachys glomerata and Fagara leprieuri were the spices with the best antioxidant activity and highest phenolic content.