Morphological characteristics, bioactive compounds content, and antioxidant activity of different accessions of African eggplant (Solanum anguivi Lam.)

Abstract

African eggplant (Solanum anguivi Lam.) fruits reportedly exhibit antidiabetic properties, possibly due to the presence of bioactive compounds. This study aimed to assess the bioactive compounds content (BCC) and antioxidant activity (AA) in the fruits of fourteen African eggplant accessions. The relationship between the fruit BCC and AA, and the plant (leaf, stem and fruit) morphological characteristics was determined. Morphological traits for the plant accessions were characterized based on existing Solanum species descriptors. Total phenolics, flavonoids, saponins, vitamin C and AA  were determined by spectrophotometry, while total alkaloids were detected by gravimetry. HPLC was used for the quantification of phenolic compounds. Morphological characteristics, BCC and AA differed among the accessions. The fruit’s accessions contained total phenolics (8.0-12.4 mg gallic acid equivalent/g dry weight (DW)), saponins (51.1-124.8 mg diosgenin equivalent/g DW), alkaloids (81.4-127.7 mg/g DW), vitamin C (3.6-6.4 mg ascorbic acid equivalent/g DW), and flavonoids (0.9-2.1 mg quercetin equivalent (QE)/ g DW) and exhibited a high AA (1.2-4.6 mg QE/g DW). Amongst the quantified phenolic compounds, chlorogenic acid (21.4-301.3 μg/ g DW) had the highest content. Cluster analyses showed that morphological characteristics might be useful to predict accessions with similar BCC and AA. Accessions with high total phenolics provided the highest AA, and, therefore, may mediate health benefits.