# Antioxidants and Antidiabetic Potential of Polyphenolic Fractions and Crude Extracts of Rhus typhina Fruit, Punica granatum L. Peel, and Terminalia catappa L. Leaves: In Vitro and In Vivo Evaluation

## TL;DR

This study evaluates the antioxidant and antidiabetic effects of extracts from sumac, pomegranate peel, and Indian almond leaves in lab and animal tests.

## Contribution

The study provides new evidence that sumac extract has strong antioxidant and antidiabetic properties, both in vitro and in vivo.

## Key findings

- Sumac extract showed the highest levels of total phenolics, flavonoids, and anthocyanins.
- Sumac extract improved glycemic control and reduced insulin resistance in diabetic rats.
- All tested extracts exhibited antioxidant and enzyme inhibition activities.

## Abstract

Rhus typhina (sumac) fruit, Punica granatum (pomegranate) peel, and Terminalia catappa (Indian almond) leaves’ extracts and their anthocyanin and non‐anthocyanin fractions were assessed in vitro for 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging, ferric reducing power (FRAP), human salivary amylase (HAS), and dipeptidyl peptidase IV (DPP‐IV) inhibitory potentials, as well as for their in vivo antidiabetic effects on high‐sugar high‐fat diet (HSHFD) + streptozotocin (STZ) induced diabetic rats (8‐weeks study), by assessing fasting blood sugar, 1 h‐ and 2 h‐oral glucose tolerance tests, serum insulin, homeostatic model assessment (HOMA) analyses, serum creatinine, urea, and blood urea nitrogen. Phytochemical analysis revealed that sumac extract had the highest total phenolic content, total flavonoid content, and total anthocyanin content followed by pomegranate peel and almond leaves. All extracts and fractions showed antioxidant (DPPH and FRAP) and enzyme (HAS and DPP‐IV) inhibition activities and also suppressed STZ effects in diabetic mice by increasing superoxide dismutase, glutathione S‐transferase, and insulin, as well as by decreasing HOMA2‐IR, urea, and creatinine, with sumac extract showing benefits even when administered prior to STZ. In addition, in vivo results showed that sumac fruit extract significantly improved glycemic control by reducing fasting blood sugar, enhancing insulin secretion, and improving insulin resistance. These findings suggest that all tested extracts, particularly sumac, possess significant antioxidant, phytochemical, and antidiabetic potential.

This graphical abstract represents the extraction, characterization, and biological evaluation of bioactive compounds derived from specific plant sources. The top section illustrates Rhus coriaria (sumac) fruit, Punica granatum (pomegranate) peel and Terminalia catappa (Indian almond) leaves', which are known for their rich phytochemical composition, including polyphenols, flavonoids, and tannins. These plant materials undergo extraction, depicted by the dropper bottle, to isolate bioactive compounds using suitable solvents and techniques. The extracted compounds are then subjected to in vitro assays for phytochemical profiling and bioactivity evaluation, in vivo studies using animal models to assess pharmacological efficacy, and potential applications in food, nutraceutical, or therapeutic formulations. This study framework emphasizes the scientific approach to exploring plant‐derived compounds for health‐related benefits.