Plant-Based Potential in Diabetes Management: In Vitro Antioxidant, Wound-Healing, and Enzyme Inhibitory Activities of Southern Algarve Species

Abstract

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by impaired glucose regulation. This study evaluated the antioxidant and antidiabetic potential of aqueous extracts from four plant species from the southern Algarve: Aristolochia baetica, Chelidonium majus, Dittrichia viscosa, and Lavandula viridis, using non-cellular in vitro assays. HPLC/PDA was used to identify active compounds. Antioxidant activity was assessed by using TAA, FRAP, RP, and DPPH assays; antidiabetic potential through α-glucosidase and α-amylase inhibition; and wound healing relevance through elastase, collagenase, and lipoxygenase inhibition. D. viscosa showed the highest antioxidant activity (FRAP: 1132.99 ± 19.54 mg TE/g dw; DPPH IC₅₀ = 25.85 ± 0.75 μg/mL) and total phenolic/flavonoid content, with a diverse profile including caffeic and chlorogenic acids, isoquercetin, and quercetin. It also exhibited potent α-glucosidase inhibition (IC₅₀ = 0.61 ± 0.06 mg/mL), outperforming acarbose. L. viridis had the highest total phenolic content (39.04 mg/g), while A. baetica demonstrated the strongest anti-elastase, anti-collagenase, and lipoxygenase activity, suggesting wound-healing potential. C. majus showed the weakest effects. A strong correlation was observed between phenolic content and antioxidant/antidiabetic activity. These findings support further in vivo studies on D. viscosa and A. baetica for potential use in T2DM management and diabetic wound healing.

Keywords: antidiabetic potential; antioxidants; diabetes mellitus; medicinal plant; wound-healing.

Figure 1

Inhibitory activity of ɑ-glucosidase and ɑ-amylase enzymes expressed as IC₅₀ (mg/mL) of the four aqueous extracts of the studied. All results are expressed as the mean IC₅₀ values ± SD (for n = 3). Different letters in the same enzyme test for the various samples (comparison of different samples in the same method) indicate that the samples have statistically significant differences determined by Games–Howell post-hoc test following one-way ANOVA (with p < 0.05). The standard inhibitor, acarbose, was included as a reference but was not subjected to statistical comparison and is therefore not assigned a superscript letter.

Figure 2

Inhibition of elastase (a), collagenase (b), and lipoxygenase (c) by the plant extracts (shown as IC₅₀ values ± SD). Different lowercase letters indicate statistically significant difference between extracts, while the (*+), (*−), and ( ) signs indicate statistically different higher, statistically different lower, and statistically non-different IC₅₀ value than the IC₅₀ value of the standard inhibitor, respectively (p < 0.05). The employed standard inhibitors are as follows: ursolic acid (anti-elastase IC₅₀ = 26.57 ± 0.37 μg/mL) (a), gallic acid (anti-collagenase IC₅₀ = 376.56 ± 7.92 go/mL) (b), and nordihydroguaiaretic acid (anti- lipoxygenase IC₅₀ = 8.21 ± 0.12 μg/mL) (c).