Chemoprevention assessment, genotoxicity and cytotoxicity of flavonoids from Inga laurina leaves (FABACEAE)

Nutritional, chemical and functional potential of Inga laurina (Fabaceae): A barely used edible species

Inga laurina is a plant species which produces edible fruits, and until now there is little information available concerning its nutritional, chemical and bioactive composition. In this study, we evaluated for the first time the proximate composition and mineral contents in its fruit (peel, pulp and seed), that is the traditionally consumed part. The seeds obtained the highest protein (19.52 g/100 g), carbohydrate (22.5 g/100 g) and mineral contents, mainly Cu, Cr, P, Mn, Se and Zn. The peel and pulp were excellent sources of fiber (4.5 and 11.05 g/100 g) as well as mineral content, with Cr and Cu standing out in the pulp. This study is notably the first to provide a detailed assessment of the nutritional compositions of traditionally consumed and not consumed parts of this fruit. Sensory analysis of the pulp was also performed, which indicated good acceptance. The antioxidant properties were characterized in the fruit, peels and leaves. The ABTS test showed that leaf supernatant hydroethanolic crude extract (EC50 = 2.70 μg/mL) and its corresponding ethyl acetate (EC50 = 1.68 µg/mL) and butanol (EC50 = 2.48 µg/mL) partitions presented higher antioxidant potential compared to the control Ginkgo biloba (EC50 = 12.17 µg/mL). The most active precipitate extract regarding DPPH was from the peel (EC50 = 13.30 μg /mL) and the most active partition was the ethyl acetate (EC50 = 13.37 μg/mL), both with better activity compared to the control Ginkgo biloba (EC50 = 46.97 μg/mL). The ethyl acetate partition (EC50 = 13.45 μg/mL) and butanol partition (EC50 = 7.97 μg/mL) from the leaves showed the highest antioxidant capacity. Thus, extracts and partitions from the peels and leaves were studied from a phytochemical point of view due to presenting the best results for antioxidant capacity. The presence of phenolic compounds such as myricetin-3-O-rhamnopyranoside, myricetin-3-O-(2″-O-galloyl)-rhamnopyranoside and myricetin-3-O-(2″,4″-di-O-galloyl)-arabinopentoside-methyl ether were observed in the leaf crude extract and polar partitions, being reported for the first time in the Inga genus and Fabaceae family. Moreover, quercetin, quercetin-3-O-galatoctoside, quercetin-3-O-rhamnopyranoside, quercetin-3-O-(2″-O-galloyl)-rhamnoside, and quercetin tri-hexose were identified in the peel crude extract and ethyl acetate partition, in which the galloyl derivative of quercetin was identified for the first time in I. laurina fruit peels. GC-MS enabled separating and identifying substances such as palmitic and stearic acids, and ethyl oleate. It is possible to conclude that I. laurina pulp can be a supplementary food as a source of phenolic compounds, and the other organs of the plant (leaves and peel) are rich in flavonoids with great antioxidant capacity, making this species a promising source of antioxidants.

Metabolic Profiling of Inga Species with Antitumor Activity

This work evaluated the metabolic profiling of Inga species with antitumor potential. In addition, we described the antigenotoxicity of polyphenols isolated from I. laurina and a proteomic approach using HepG2 cells after treatment with these metabolites. The in vitro cytotoxic activity against HepG2, HT-29 and T98G cancer cell lines was investigated. The assessment of genotoxic damage was carried out through the comet assay. The ethanolic extract from I. laurina seeds was subjected to bioassay-guided fractionation and the most active fractions were characterized. One bioactive fraction with high cytotoxicity against HT-29 human colon cancer cells (IC₅₀ = 4.0 µg mL⁻¹) was found, and it was characterized as a mixture of p-hydroxybenzoic acid and 4-vinyl-phenol. The I. edulis fruit peel (IC₅₀ = 18.6 µg mL⁻¹) and I. laurina seed (IC₅₀ = 15.2 µg mL⁻¹) extracts had cytotoxic activity against the cell line T98G, and its chemical composition showed a variety of phenolic acids. The chemical composition of this species indicated a wide variety of aromatic acids, flavonoids, tannins, and carotenoids. The high concentration (ranging from 5% to 30%) of these polyphenols in the bioactive extract may be responsible for the antitumor potential. Regarding the proteomic approach, we detected proteins directly related to the elimination of ROS, DNA repair, expression of tumor proteins, and apoptosis.