Antidiabetic Potential of Hylocereus Polyrhizus and Hylocereus Megalanthus Fruit Peel: An In vitro Study

ABSTRACT

Background:

Diabetes is a chronic metabolic condition affecting mainly carbohydrate metabolism. Dragon fruit is a commonly consumed fruit in Asia-pacific countries, with reported anti-diabetic potential.

Objectives:

The presents study explores the use of dragon fruit peel as an anti-diabetic supplement.

Materials And Method:

Fruit peels from two varieties (Red and Yellow) were evaluated for their ability to absorb glucose, inhibit glucose diffusion, and inhibit starch digestion using in vitro models.

Result:

Both red and yellow dragon fruit peel powder samples decreased starch digestion significantly compared to wheat bran and inhibited glucose diffusion, as indicated by the glucose dialysis retardation index (GDRI) values.

Conclusion:

The findings of the study indicate that both red and yellow dragon fruit peel possesses significant antidiabetic potential.

INTRODUCTION

Diabetes is a metabolic disorder of multiple ethology affecting carbohydrate metabolism, resulting in high blood glucose levels, which often lead to chronic illness. Type 2 diabetes can be caused by insulin insufficiency or inefficiency. Therefore, effective control of postprandial hyperglycemia is of prime importance in the management of diabetes.[1] Delaying carbohydrate digestion by inhibiting carbohydrate-hydrolyzing enzymes and retarding their diffusion is believed to be one of the most important approaches to control postprandial hyperglycemia.[2] Consequently, a number of natural products, including food sources and herbs, have been explored for their potential antidiabetic effects.[3] Studies have established that plant fibers and phenolic compounds found in most of the fruits and vegetable are effective inhibitors of carbohydrate-hydrolyzing enzymes, delaying starch digestion and glucose absorption.[2]

Dragon fruit is one of the commonly consumed fruit in Asia-pacific countries and has been reported to have significant anti-diabetic potential.[4] Some clinical trials have also found dragon fruit to be beneficial in controlling blood glucose levels in prediabetic and type 2 diabetics.[5] The skin of dragon fruit, a valuable by-product rich in a number of antioxidant phytochemicals such as battalions, α-amyrin, β-amyrin, octacaine, and γ-sitosterol, is wasted.[6]

The current research was conducted to explore the anti-diabetic efficacy of red and yellow dragon fruit (Hylocereus polytheizes and Hylocereus megalanthus) peels using suitable in vitro techniques.

MATERIALS AND METHODS

Fruit peels of red and yellow dragon fruit were separated from the pulp and dried separately in a hot air oven at 60°C for 24 hours. The dried samples were then powdered to pass through a 60-mesh sieve (BS) using a compact cyclonic laboratory mill to yield red dragon fruit peel powder (RDFPP) and yellow dragon fruit peel powder (YDFPP), which were stored in air-tight containers in a refrigerator. Wheat bran was purchased from the local market.

Glucose absorption capacity and effect on the retardation of glucose diffusion of wheat bran and dragon fruit samples were determined as described by Ahmed and Urooj.[7] The glucose diffusion retardation index (GDRI) was calculated using the following formula.

The kinetics of in vitro amylolysis were ascertained for the samples using the Ahmed and Urooj method. 7. The glucose oxidase-peroxidase test kit was used to measure the amount of glucose in the dialysate at 1–4 hours. The control experiment was conducted without a sample.

The obtained data were statistically evaluated using ANOVA and Tukey’s multiple comparison post-hoc test, using SPSS 21.0 software at P ≤ 0.05.

RESULTS

The glucose adsorption capacities of red dragon fruit peel powder (RDFPP) and yellow dragon fruit peel powder (YDFPP) [Figure 1]. While RDFPP and YDFPP had equal glucose adsorption capacities, theirs was substantially (P < 0.05) higher than that of wheat bran (WB). Both RDFPP and YDFPP adsorbed significant amounts of glucose molecules and prevented their diffusion across the dialysis membrane by 16% at 240 min time interval [Table 1]. The samples also decreased starch digestion significantly compared to wheat bran, as indicated by glucose dialysis retardation index (GDRI) values. GDRI values decreased over time, and both samples exhibited a comparable GDRI value of 14% at 240 min [Table 2].

Figure 1.

Sample’ impact on glucose adsorption. WB-wheat bran; RDFPP-red dragon fruit peel powder; YDFPP-yellow dragon fruit peel powder

Table 1.

Samples’ impact on glucose diffusion

Sample	Glucose content in the dialysate (mM)/GDRI*
	1 hour	2 hour	3 hours	4 hours
Control	1.25d (0.0)	1.70d (0.0)	2.03d (0.0)	2.25d (0.0)
WB (2%)	1.13c (18.30)	1.40c (16.1)	1.70c (13.91)	2.01c (11.10)
Acarbose	0.75a (44.7)	1.03a (38.7)	1.31a (29.9)	1.71a (20.13)
RDFPP (1%)	0.95b (30.01)	1.35b (20.04)	1.62b (18.13)	1.83b (16.11)
YDFPP (1%)	0.93b (29.11)	1.34c (20.00)	1.64bc (18.27)	1.81b (16.00)

*Values in parenthesis represent GDRI

Table 2.

Samples’ impact on the kinetics of in vitro amylolysis

Sample	Glucose content in the dialysate (mM)/GDRI*
	1 hour	2 hours	3 hours	4 hours
Control	0.31c (0.0)	0.47c (0.0)	0.64c (0.0)	0.81c (0.0)
Acarbose (0.2%)	0.00a (100)	0.00a (100)	0.00a (100)	0.00a (100)
RDFPP (1%)	0.07b (67.3)	0.25b (41.7)	0.53b (11.3)	0.63b (14.7)
YDFPP (1%)	0.10b (61.7)	0.31b (35.4)	0.60c (10.3)	0.71b (13.1)

*Values in parenthesis represent GDRI

DISCUSSION

The glucose-binding efficacy of the samples was directly comparative to the glucose levels in the present study. This observation is in good agreement with an earlier study by Ahmed and Urooj.[7] The glucose adsorption capability of RDFPP and YDFPP was comparable with each other but significantly higher (P ≤ 0.05) than that of WB. This observation can be attributed to the higher soluble fiber content in dragon fruit peel compared to WB.[4] GDRI is considered a useful in vitro index to calculate in vivo retardation of glucose absorption in the digestive tract.[7]

According to Panjaitan and Novitasari[8] and Sumartin et al.,[9] rats’ blood glucose concentrations may drop as a result of the red dragon fruit peel’s ethanol extraction. Dragon fruit peel powder (DFP) can improve the nutritional value and practical qualities of cookies when added to uncooked cookie dough.[10] Poolsup et al.[5] from a systematic review concluded that dragon fruits can helps in reducing blood glucose levels.

The efficacy of any sample to inhibit starch digestion and trap liberated glucose from diffusing across the dialysis bag indicates its potential to be used as an antidiabetic therapeutic. Ahmed et al.,[2] found that GDRI values reduced consistently over the time period with different fibers. Acarbose showed a maximum GDRI of 100 at all times, indicating complete retardation of starch digestion and glucose diffusion. These finding substantiate the use of acarbose in diabetes and also support the use of dragon fruit peel, which is a food by-product.

CONCLUSION

The findings of the study indicate that both RDFPP and YDFPP significant antidiabetic potential in vitro.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.