α-Glucosidase and advanced glycation end products inhibition with Vernonia amygdalina root and leaf extracts: new data supporting the antidiabetic properties

Abstract

Objective This study aims to investigate antidiabetic activity of several Vernonia amygdalina extracts to study their potential use in medicine. Methods Aqueous and ethanol extracts were obtained by maceration and Soxhlet extraction from roots and leaves of V. amygdalina. The extracts were tested as inhibitors of α-glucosidase activity and of advanced glycation end products (AGEs) formation. Further, radical scavenging activity was examined detecting the oxygen radical absorbance capacity, while the potential cytotoxicity of extracts was estimated with MTT assay. Key findings In aqueous and ethanol extracts, several polyphenolic compounds were identified; in detail, (-)-catechin and luteolin were found in leaf extracts, while caffeic acid, chlorogenic acid and the terpenoid vernodalol were recognized in root extracts. Regarding antidiabetic activity, the aqueous root extracts efficiently inhibited α-glucosidase activity in a concentration-dependent manner (IC50 = 5.6 µg/ml and 39.8 µg/ml, respectively of macerated and Soxhlet extracts), whereas those obtained from leaves exhibited lower potency. Furthermore, AGEs formation was reduced by all V. amygdalina extracts starting from 10 µg/ml. Conclusions The aqueous extracts of V. amygdalina roots obtained by maceration and Soxhlet extraction show remarkable anti-α-glucosidase activity, and all extracts have favourable antiglycation and antioxidant activities.

Anti-α-Glucosidase and Antiglycation Activities of α-Mangostin and New Xanthenone Derivatives: Enzymatic Kinetics and Mechanistic Insights through In Vitro Studies

“…The oxygen radical absorbance capacity (ORAC) assay allows evaluating the ability of substances to interfere with oxidative reactions induced by peroxidic radicals. The assay was performed as previously reported [47,48]. Briefly, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) was prepared in phosphate buffer in a concentration range of 6.25-50 µM.…”

Luteolin and Vernodalol as Bioactive Compounds of Leaf and Root Vernonia amygdalina Extracts: Effects on α-Glucosidase, Glycation, ROS, Cell Viability, and In Silico ADMET Parameters

“…(Asteraceae), also known as ‘bitter leaf’ or ‘ndolé’ due to the bitter taste of the leaves, is an African and Asian medicinal plant well known for its use in traditional medicine in various diseases, including wound healing, malaria, hypertension, and DM [ 3 , 4 , 5 ]. Ethanol and aqueous Vernonia amygdalina (VA) extracts and their in vitro activity were studied as potential agents capable of counteracting hyperglycemia and the production of advanced glycation end products (AGEs), showing their activity against α-glucosidase activity and AGEs [ 6 ]. Furthermore, other authors have reported antidiabetic effects in diabetic rat models [ 7 , 8 , 9 , 10 , 11 , 12 , 13 ].…”

“…Studies have revealed the presence in VA tissues of several phytochemicals, such as polyphenols, alkaloids, saponins, and steroid glycosides [ 6 , 15 , 16 ]. Although flavonoids are common compounds in many types of plants, which are also used for food, terpene-derived compounds are less documented.…”

“…Luteolin is a yellow flavonoid well-known for its antioxidant, anti-inflammatory, and potential anticancer activities [ 17 , 18 , 19 ]. Luteolin is very common in fruits and vegetables for food use, but it is also found in many medicinal plants, among those VA [ 6 , 16 , 20 ]. Luteolin has anti-inflammatory (through the inhibition of NF-κB, ERK1/2, MAPK, JNK, IL-6, IL-8, and TNF-α) and antioxidant (reducing reactive species and increasing endogenous antioxidants) activities [ 19 ].…”

“…Vernodalol is a sesquiterpene lactone isolated from the roots and leaves of VA and other Vernonia species [ 6 , 25 , 26 , 27 ], and also from the seeds of Chenopodium anthelminticum and Distephanus angulifolius [ 28 ]. It shows several activities, including antileishmaniasis, insecticidal, and antimicrobial properties against bacteria and fungi [ 5 , 29 , 30 , 31 ].…”