Throwing light on the antidiabetic, anti-inflammatory and antioxidant nature of the leaves of tree tomato (Solanum betaceum Cav.)

Tamarillo, commonly known as tree tomato (Solanum betaceum) is cultivated for its edible fruits, whose biological activities have been explored. In this study, the antidiabetic, anti-inflammatory, and antioxidant properties of methanolic leaf extracts from red-fruit and yellow-fruit cultivars of S. betaceum were investigated. Leaves of red-fruit cultivars displayed significantly (P < 0.05) higher levels of total flavonoid and terpenoid content compared to yellow-fruit cultivars. The antidiabetic activity was assessed by analyzing the inhibition of α-amylase activity. The leaf extract from red-fruit cultivars demonstrated higher α-amylase inhibiton activity, with an IC₅₀ value of 79.71 µg/ml, compared to yellow-fruit cultivars, which had an IC₅₀ value of 89.97 µg/ml. While the α-amylase inhibition activity of the leaf extracts from both cultivars was lower than that of the standard drug acarbose, this might be considered beneficial. Acarbose exhibits potent α-amylase inhibition, which can lead to the accumulation of undigested carbohydrates in the colon, potentially causing adverse effects. The anti-inflammatory nature was evaluated through protein denaturation inhibition and lipoxygenase inhibition assays. The leaf extracts from red-fruit cultivars exhibited greater inhibition of protein denaturation and lipoxygenase activity than the yellow-fruit cultivars. However, the anti-inflammatory activity of the standard drug aspirin was much higher than that of the leaf extracts from red-fruit cultivars. The antioxidant potential was determined using DPPH and ABTS radical scavenging assays. The leaf extracts of red-fruit cultivars registered significantly higher antioxidant activities compared to those of yellow-fruit cultivars. The ascorbic acid standard exhibited much higher antioxidant potential, with IC₅₀ values of 27.47 µg/ml by the DPPH method and 24.51 µg/ml by the ABTS method. The IC₅₀ values observed in this study could be reduced through the purification of crude leaf extracts. Furthermore, identifying individual molecules in the leaf extracts through techniques such as chromatography, mass spectrometry, bioactivity-guided fractionation, and NMR spectroscopy can facilitate the development of drugs for degenerative diseases.