A biosynthetic intermediate of phytoalexins in banana fruits

Screening of Musa balbisiana Colla. seeds for antidiabetic properties and isolation of apiforol, a potential lead, with antidiabetic activity

BACKGROUND

'Phytonutrients' have been reported to exert an incredible impact on the healthcare system and offer medical benefits including the prevention or treatment of lifestyle-associated diseases. We chose one of the most common and important plant families, Musaceae, for our present study and explored its antidiabetic potential.

RESULTS

Seeds of the edible fruits of Musa balbisiana Colla. were investigated for their antidiabetic potential. After estimating the proximate composition, the seeds were extracted with various solvents and evaluated for antidiabetic potential in terms of the inhibition of digestive enzymes, antiglycation activity and in vitro glucose uptake. The acetone extract demonstrated the highest inhibition of α-amylase and α-glucosidase enzymes with IC₅₀ values of 36.67 ± 0.367 and 100.61 ± 0.707 µg mL^-1 , respectively. The extract also exhibited significant glycation inhibition with an IC₅₀ value of 86.48 ± 0.751 µg mL^-1 . Furthermore, a major phytochemical, apiforol, was isolated from the acetone extract for the first time, which demonstrated promising α-glucosidase inhibition (IC₅₀  = 48.25 ± 0.255 µmol L^-1 ), antiglycation property (IC₅₀  = 114.23 ± 0.567 µmol L^-1 ) and enhanced glucose uptake in L6 myoblasts. In molecular docking studies, apiforol efficiently bonded to the active sites of α-glucosidase enzyme 3A4A.

CONCLUSIONS

As dietary intervention is one of the effective strategies for addressing diabetes, special attention is always given to natural food bio-actives or agro-products for better human health. The results of our study suggest that Musa balbisiana has significant potential as an ingredient in health food formulations by reducing postprandial hyperglycaemia. © 2018 Society of Chemical Industry.

Phenylphenalenones protect banana plants from infection by Mycosphaerella fijiensis and are deactivated by metabolic conversion

Phenylphenalenones, polycyclic aromatic natural products from some monocotyledonous plants, are known as phytoalexins in banana (Musa spp.). In this study, (1) H nuclear magnetic resonance (NMR)-based metabolomics along with liquid chromatography and mass spectrometry were used to explore the chemical responses of the susceptible 'Williams' and the resistant 'Khai Thong Ruang' Musa varieties to the ascomycete fungus Mycosphaerella fijiensis, the agent of the black leaf Sigatoka disease. Principal component analysis discriminated strongly between infected and non-infected plant tissue, mainly because of specialized metabolism induced in response to the fungus. Phenylphenalenones are among the major induced compounds, and the resistance level of the plants was correlated with the progress of the disease. However, a virulent strain of M. fijiensis was able to overcome plant resistance by converting phenylphenalenones to sulfate conjugates. Here, we report the first metabolic detoxification of fungitoxic phenylphenalenones to evade the chemical defence of Musa plants.