This research analyzed the major chemical components and multiple antioxidant activities present in the fresh juice of eight vegetables, and studied their influence on starch induced postprandial glycemia in rats. A SDS-PAGE based protein fingerprint of each vegetable juice was also prepared. The yields of juice, chemical components like total proteins, total polyphenols, total flavonoids, total anthocyanins and free radicals like the ABTS˙(+) cation, DPPH, H(2)O(2), scavenging activities and reducing properties for NBT and FeCl(3) showed wide variations. Vegetable juice from brinjal ranked first in displaying total antioxidant capacity. Pretreatment of rats with vegetable juices moderated starch induced postprandial glycemia. The fresh juice from the vegetables ridge gourd, bottle gourd, ash gourd and chayote significantly mitigated postprandial hyperglycemic excursion. Total polyphenol concentrations present in vegetable juices positively influenced ABTS˙(+) scavenging activity and total antioxidant capacity. However, NBT reducing activity of juices was positively affected by total protein concentration. Contrarily, however, high polyphenol content in vegetable juice was observed to adversely affect the postprandial antihyperglycemic activity of vegetable juices. This is the first report exploring antihyperglycemic activity in these vegetable juices and highlights the possible adverse influence of high polyphenol content on the antihyperglycemic activity of the vegetable juices.

Objective:Consumption of green-leafy vegetables is being advocated beneficial for type 2 diabetes mellitus individuals possibly because they are cost effective source of potent biological antioxidants. This research analyzed various phytochemicals, free radicals scavenging antioxidant potentials and starch digesting enzymes inhibitory activities in fresh juice of nine green-leafy vegetables. Furthermore, this study also investigated influence of these vegetables juice on starch and glucose induced postprandial glycemic load.Materials and Methods:Phytochemical constituents, in vitro free radicals scavenging antioxidant and enzymes inhibitory activities were evaluated applying various reported methods. Post-prandial glycemic excursion was induced in rats pretreated with vegetables juice by oral administration of starch and glucose.Results:All the leafy vegetables juice displayed potent free radicals scavenging activities. Juice of amaranthus, rumex, palak and raphanus displayed potential anti-oxidative property by reducing H2O2 induced hemolysis in rats red blood cells RBCs. Ajwain and rumex juice showed pancreatic α-amylase inhibitory activity. Alternanthera, ajwain, methi, amaranthus and sowa leaves juice displayed intestinal α-glucosidase inhibitory activity. Juice of raphanus, ajwain and sowa significantly mitigated starch-induced postprandial glycemic load. Amaranthus leaves juice potently mitigated glucose-induced postprandial glycemic load and also reduced hemoglobin glycation induced by glucose in vitro.Conclusions:This investigation finds that juice of leafy vegetables is potent source of biological antioxidants. In addition, juice of raphanus, ajwain and sowa leaves possess capacity to mitigate starch induced postprandial glycemic burden and amaranthus leaves’ juice can reduce glucose induced postprandial glycemic excursion.

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Aims Plant extracts have long been used for the ethnomedical treatment of diabetes, microbial infections and as a source of antioxidant. This study was aimed at investigating the antidiabetic, antioxidant, and antimicrobial activities of the n-hexane and ethyl acetate extract of Tephrosia bracteolata leaves (TBL) as associated with the ethnobotanical knowledge of the local people of Nigeria. Main methods The phytochemical composition of the n-hexane and ethyl acetate extract of the leaves of T. bracteolata were determined following standard procedures in literature, and it's in vitro inhibitory activities against α-glucosidase enzyme. 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS .+ ) and 1,1-diphenyl-2-picrylhydrazyl (DPPH + ) antioxidant activities were also examined. Well diffusion method was employed in evaluating the antimicrobial property of the extracts. Key findings The ethyl acetate extract of T. bracteolata leaves had the greatest inhibitory effect on α-glucosidase, followed by the n-hexane with IC 50 43.95 μg/ml and IC 50 ˃50 μg/ml respectively. The ethyl acetate also exhibited significant DPPH + and ABTS .+ antioxidant activity with IC 50 of 24.96 μg/ml and 6.48 μg/ml as compared to Ascorbic acid and Trolox (12.24 μg/ml and 5.91 μg/ml) respectively. The zones of inhibition of the ethyl acetate extract of T. bracteolata leaves ranges from 10 – 25 mm at a concentration of 6.25–200 mg/ml, and it showed a greater antibacterial activity than the n-hexane extract, having a zone of inhibition from 10 – 20 mm at concentration of 12.5–200 mg/ml when compared to the standard Gentamycin. Similarly, the ethyl acetate extract of T. bracteolata showed a better anti fungi activity at concentration range 12.5–200 mg/ml than the n-hexane extract at concentration range of 25–200 mg/ml with reference to Tioconazole. These results indicated for the first time that the ethyl acetate extract of T. bracteolata leaves extracts exerted potent inhibitory effects against α-glucosidase, actively scavenge DPPH + and ABTS .+ free radicals and successfully inhibits the proliferation of Gram positive and Gram negative microorganism. Significance TBL is an important source of antidiabetic, antimicrobial and antioxidant agent.

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