Comparative Study of Leaf and Rootstock Aqueous Extracts of Foeniculum vulgare on Chemical Profile and In Vitro Antioxidant and Antihyperglycemic Activities

Abstract

Foeniculum vulgare is a medicinal plant used in Moroccan folk medicine to treat several diseases such as diabetes. The aim of this study was to determine the phenolic bioactive compounds and to evaluate the antioxidant and antihyperglycemic activities of Foeniculum vulgare leaf and rootstock extracts. Phenolic compounds of F. vulgare rootstock and leaf extracts were determined using HPLC-DAD-QTOFMS analysis. The antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) radicals. Moreover, the in vitro antihyperglycemic effects were tested by measuring the inhibition of α-amylase and α-glucosidase activities. HPLC-DAD-QTOFMS analysis identified thirty-two phenolic components in both leaf and rootstock extracts. Caffeic acid, quinic acid, and chlorogenic acid were the major compounds of F. vulgare leaf extract (FVLE), while the main compound of F. vulgare rootstock extracts (FVRE) was quinic acid. In the DPPH assay, F. vulgare leaf extract showed important antioxidant activity (IC50 = 12.16 ± 0.02 μg/mL) than F. vulgare rootstock extract (IC50 = 34.36 ± 0.09 μg/mL). Moreover, fennel leaf extracts revealed also the most powerful antioxidant activity (IC50 = 22.95 ± 0.4 μg/mL) in the ABTS assay. The in vitro antihyperglycemic activity showed that F. vulgare rootstock extract exhibited a remarkable inhibitory capacity (IC50 = 194.30 ± 4.8 μg/mL) of α-amylase compared with F. vulgare leaf extract (IC50 = 1026.50 ± 6.5 μg/mL). Furthermore, the inhibition of α-glucosidase was more importantly with F. vulgare rootstock (IC50 of 165.90 ± 1.2 μg/mL) than F. vulgare leaf extracts (203.80 ± 1.3 μg/mL). The funding of this study showed that F. vulgare rootstock and leaf extracts presented several phenolic compounds and showed important antioxidant and antidiabetic effects. We suggest that the identified molecules are responsible for the obtained activities. However, further studies focusing on the isolation and the determination of antioxidant and antidiabetic effects of F. vulgare rootstock and leaf main compounds are required.

Extraction, characterization of polyphenols from certain medicinal plants and evaluation of their antioxidant, antitumor, antidiabetic, antimicrobial properties, and potential use in human nutrition

“…The current study showed weaker inhibitory activity of methanolic extracts of C. absus than a previous contrasting study which reported that hydroalcoholic extracts of C. absus had potent inhibitory activity against α-glucosidase ( 119 ). However, The results of the present investigation are per the majority of earlier research, which reported that C. citratus ( 115 ), M. arvensis ( 120 ), F. vulgare ( 121 ) had strong α-glucosidase inhibition activity due to their high phytochemical contents, such as alkaloids, flavonoids, and saponins that bind other non-competitive enzymes ( 119 ).…”

“…The main mechanisms of caffeic acid, which regulates blood glucose levels, are stimulating insulin production, triggering glucose uptake by adipocytes in the liver, and reducing the glucose level in the bloodstream. In general, phenolic compounds can alter carbohydrate metabolism by their binding affinity towards hydrolyzing enzymes ( 121 ). Present study confirms the antidiabetic activity of selected plant extracts which indicates their suitability for use in therapeutic medicine.…”

Top Edible Wild Plants of Eastern Mediterranean Region. Part III: Antidiabetic Activity

“…A. Bashkin and his colleagues found that two of the D-P have very weak α-amylase inhibition: F. vulgare and G. tournefortii [106]. This contradicts previous reports for F. vulgare [47,52,57], and even more for G. tournefortii [65], where M. Keskin and her colleagues reported very high activity of this enzyme inhibition: IC 50 = 4.22 mg/mL. And the last contradiction for F. vulgare, we find in the report of F. Amirkhanloo and her colleagues that the essential oil of this plant could not improve insulin resistance in women with polycystic ovary syndrome, PCOs [107].…”

“…4. [52] Seeds were extracted with 20% aqueous ethanol, and cookies that contained 3% extract were supplemented to hyperglycemic human subjects (4 cookies in a single dose, mass not indicated). Tests indicated significant reduction of blood glucose concentrations [53].…”

Fennel Essential Oil as a Complementary Therapy in the Management of Diabetes

“…Until now, only a few research studies have assessed the effects of fennel products on diabetes. Most studies were performed in vitro, but preclinical studies have evaluated the effects of different extracts from fennel on diabetic rats [ 13 , 14 , 15 ]. While the in vitro studies have shown promising effects, information from in vivo studies is scarce.…”