In Vivo Screening and Antidiabetic Potential of Polyphenol Extracts from Guava Pulp, Seeds and Leaves

SIMPLE SUMMARY: The incidence of diabetes has risen from 151 million people in 2000 to 463 million in 2019, with 4.2 million estimated deaths in 2019, and over 700 million people will be affected with diabetes worldwide by 2045. Thus, the screening of anti-diabetic plants is inevitable in order to overcome diabetes. This study has investigated the anti-diabetic potential of polyphenol extracts from guava leaves, seeds and pulp using an albino rat model. The in vivo study has reported that polyphenols from leaves and pulp have an ability to improve diabetic parameters, such as insulin, blood glucose and triglycerides levels. The improvement in blood parameters is also an indication of these extracts that are valuable for diabetes management. The findings of this study reveal that polyphenols from guava leaves, pulp and seeds can be used for drug development. ABSTRACT: The present study investigates the antidiabetic potential of polyphenol extracts purified from guava pulp, seeds and leaves using an in vivo experiment on albino rats. The polyphenols from guava pulp, seeds and leaves were extracted using methanol solvent and the sonication method while being evaluated by total phenolic contents and radical scavenging activity assay. The proximate composition of powders revealed that ash, protein and total sugars were significantly (p < 0.05) higher in leaves and seeds, while vitamin C was highest in pulp. Total phenolic and antioxidant activities were highest in pulp followed by leaves and seeds. The findings of feed intake and body gain revealed that the supplementation of polyphenols, especially from pulp, significantly (p < 0.05) increased the feed intake, which resulted in increased body weight. Moreover, total cholesterol (TC) and low-density lipoprotein (LDL) levels were significantly (p < 0.05) decreased, while the level of high-density lipoprotein (HDL) was increased in groups fed with polyphenols from guava pulp compared to both (+ive and –ive) control groups. Furthermore, blood glucose and triglycerides were significantly (p < 0.05) decreased in supplemented groups compared to the control group of diabetes mice, which resulted in the inhibition of α-amylase and glucose transport. Besides this, packed cell volume (PCV), mean corpuscular volume (MCV), hemoglobin, red blood cells (RBCs), white blood cells (WBCs) and platelet levels were increased significantly (p < 0.05) in pulp’s extract followed by leaves and seeds compared to both control groups. Overall, the antidiabetic potential of different extracts was in the following order: pulp > leaves > seeds. The findings suggest the feasibility of adding 200–250 mg/kg.bw of polyphenol extracts of pulp as an alternative to diabetic drugs.