Medicinal Plants Classification Biosynthesis and ... - Index of

Management of Diabetes with Diet and Plant-Derived Drugs
extracts showed less α-amylase inhibition which indicates the potential to overcome the side
effects of undigested starch, and thus may have benefits for the management of
hyperglycemia (28). Routine consumption of green tea has been reported as showing
beneficial effects on various metabolic disorders such as Type II diabetes, obesity and
cardiovascular risks because of its catechin (specifically EGCG (-)-epigallocatechin-3gallate)
content in various in vitro and animal studies (29).
Varieties of pumpkin (Cucurbita pepo), maize (Zea mays) and beans (Glycine max,
Vigna angularis, Canavalia spp., Cicer arietinum, and Canavalia ensiformis) have been
screened using in vitro enzyme (α-glucosidase, α-amylase and ACE-I) inhibition assays.
Round orange and spotted orange green pumpkin extracts had the highest content of total
phenolics and moderate antioxidant activity, the highest potential for glucosidase and ACE-I
inhibition and may thus help in reducing hyperglycemia and associated complications linked
to cellular oxidation stress and hypertension. Selected types of pumpkin, beans and maize
varieties have moderate phenolic content with moderate free radical scavenging linked
antioxidant activity and thus may be of value in reducing hyperglycemia-induced
microvascular complications (30).
Aqueous extracts of nine types of pepper, Capsicum annum, (green, red, orange, yellow,
cubanelle, red sweet, yellow sweet, long hot and jalapeno) were investigated for inhibitory
activities against α-glucosidase, α-amylase and ACE-I. Green, red sweet, long hot and yellow
sweet had high inhibitory activity against α-glucosidase from both rat intestine and yeast; red
sweet possessed highest α-amylase activity and yellow pepper had the highest ACE-I
inhibitory activity followed by cubanelle, red and red sweet. Some peppers showed high αglucosidase
with low α-amylase activity which could be a good dietary strategy to control
glucose absorption without the side effects of undigested starch. This study indicated that
peppers are rich in phenolic phytochemicals and have high free radical scavenging-linked
antioxidant activity. These foods have the potential to reduce hyperglycemia-induced
vascular complications and tissue damage resulting from oxidation and help reduce
hyperglycemia and related long term complications of diabetes (e.g. hypertension) (31).
Dried cranberry powder, dried oregano, and rosemary powders were screened using the same
enzyme assays mentioned above. Water extracts of pure dried oregano exhibited the greatest
α-glucosidase and α-amylase inhibition, water extracts of oregano had the greatest DPPH
radical inhibition activity and pure cranberry had the greatest ACE-I inhibitory activity (32).
Legumes, including soybeans chickpeas, lentils, kidney beans, cannellini beans,
soybeans, berlotti beans, baked beans and peanuts, reduce the risk of developing Type II
diabetes as they are low in fat, high in fibre, are a good source of protein and have low
glycemic index. Animal studies of obesity and diabetes showed soybeans reduced serum
insulin and insulin resistance, while a study of middle aged Chinese women has also shown
that consumption of legumes, in particular soybeans, was inversely associated with the risk of
Type II diabetes (33). Alpha-amylase inhibitor (α-AI) has been isolated and purified from
kidney beans (Phaseolus vulgaris L. cv Tendergreen). Two isoforms, α-AI1 and α-AI1 , of 43
kDa have been isolated with a difference in their isoelectric point and neutral sugar content.
The major isoform, α-AI1 inhibited human and porcine pancreatic α-amylase (PPA) but not
bacterial or fungal α-amylase enzymes (34). Douchi, a fermented soybean Chinese food, has
been screened for α-glucosidase inhibition and found to have high activity. Douchi sourced
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