Abstract:
ETHNOPHARMACOLOGICAL RELEVANCE : Culinary herbs and spices are widely used ethnomedically across Africa. They are traditionally employed
in the treatment of several ailments including inflammation disorders, pain alleviation and infectious
diseases. Pharmacological studies are necessary to provide a scientific basis to substantiate their
traditional use and safety. In this study, the 15-lipoxygenase inhibitory, antioxidant, antimycobacterial
and the cytotoxic activities, total phenolic and flavonoid contents of fourteen edible plants were
investigated.
MATERIALS AND METHODS :
The 15-lipoxygenase inhibitory activity was evaluated by the ferrous oxidation-xylenol orange (FOX)
assay method. The antioxidant activity was determined using free-radical scavenging assays. The
antimycobacterial activity was determined by a broth microdilution method against three species of
mycobacteria: Mycobacterium smegmatis, Mycobacterium aurum and Mycobacterium fortuitum using
tetrazolium violet as growth indicator. The cytotoxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)-
2,5-diphenyltetrazolium bromide (MTT) assay on Vero monkey kidney cells.
RESULTS :
All the extracts tested had some 15-lipoxygenase inhibitory activity ranging from 32.9-78.64%.
Adansonia digitata (fruit) had the highest antioxidant capacity (IC50 values of 8.15 μg/mL and 9.16
μg/mL in the DPPH and ABTS assays respectively; TEAC of 0.75 in the FRAP assay) along with the
highest amount of total phenolics (237.68 mg GAE/g) and total flavonoids (16.14 mg QE/g). There were
good correlations between DPPH and ABTS values (R2 0.98) and between total phenolics and total
flavonoids (R2 0.94). Tamarindus indica had significant antimycobacterial activity against M. aurum
(MIC 78 μg/mL). As could be expected with edible plants, all the extracts had a relatively low
cytotoxicity with LC50 values higher than 102 μg/mL with the exception of the two Aframomum species
(33 and 74 μg/mL).CONCLUSIONS : This study provides scientific support for some of the the traditional uses and the pharmacological
activities of the culinary herbs and spices investigated. The results suggest that increasing intake of some
of these herbs may be useful in preventing or reducing the progression of lifestyle-related diseases. The
diversity of the pharmacological activities of the extract from the fruit of Adansonia digitata suggested
that this plant might be valuable for application in human and animal health.
