Diabetes Mellitus (DM) is a metabolic disorder that is spreading alarmingly around the globe. Type-2 DM (T2DM) is characterized by low-grade inflammation and insulin resistance and is closely linked to obesity. T2DM is mainly controlled by lifestyle/dietary changes and oral antidiabetic drugs but requires insulin in severe cases. Many of the drugs that are currently used to treat DM are costly and present adverse side effects. Several cellular, animal, and clinical studies have provided compelling evidence that flavonoids have therapeutic potential in the management of diabetes and its complications. Quercetin is a flavonoid, present in various natural sources, which has demonstrated in vitro and in vivo antidiabetic properties. It improves oral glucose tolerance, as well as pancreatic β-cell function to secrete insulin. It inhibits the α-glucosidase and DPP-IV enzymes, which prolong the half-life of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). Quercetin also suppresses the release of pro-inflammatory markers such as IL-1β, IL-4, IL-6, and TNF-α. Further studies are warranted to elucidate the mode(s) of action of quercetin at the molecular level. This review demonstrates the therapeutic potential of quercetin in the management of T2DM.

Diabetes mellitus is a chronic complication that affects people of all ages. The increased prevalence of diabetes worldwide has led to the development of several synthetic drugs to tackle this health problem. Such drugs, although effective as antihyperglycemic agents, are accompanied by various side effects, costly, and inaccessible to the majority of people living in underdeveloped countries. Medicinal plants have been used traditionally throughout the ages to treat various ailments due to their availability and safe nature. Medicinal plants are a rich source of phytochemicals that possess several health benefits. As diabetes continues to become prevalent, health care practitioners are considering plant-based medicines as a potential source of antidiabetic drugs due to their high potency and fewer side effects. To better understand the mechanism of action of medicinal plants, their active phytoconstituents are being isolated and investigated thoroughly. In this review article, we have focused on pharmacologically active phytomolecules isolated from medicinal plants presenting antidiabetic activity and the role they play in the treatment and management of diabetes. These natural compounds may represent as good candidates for a novel therapeutic approach and/or effective and alternative therapies for diabetes.

Cancer is a leading cause of death worldwide and involves an oxidative stress mechanism. The transcription factor Nrf2 has a crucial role in cytoprotective response against oxidative stress, including cancer growth and progression and therapy resistance. For this reason, inhibitors of Nrf2 are new targets to be studied. Traditional plant-based remedies rich in phytochemicals have been used against human cancers and phenolic compounds are known for their chemopreventive properties. This comprehensive review offers an updated review of the role of phenolic compounds as anticancer agents due to their action on Nrf2 inhibition. In addition, the role of naturally-occurring bioactive anticancer agents are covered in the clinical applications of polyphenols as Nrf2 inhibitors.

Conditions like diabetes mellitus (DM), cancer, infections, inflammation, cardiovascular diseases (CVDs), and gastrointestinal (GI) disorders continue to have a major global impact on mortality and morbidity. Medicinal plants have been used since ancient times in ethnomedicine (e.g., Ayurveda, Unani, Traditional Chinese Medicine, and European Traditional Medicine) for the treatment of a wide range of disorders. Plants are a rich source of diverse phytoconstituents with antidiabetic, anticancer, antimicrobial, antihypertensive, antioxidant, antihyperlipidemic, cardioprotective, immunomodulatory, and/or anti-inflammatory activities. This review focuses on the 35 plants most commonly reported for the treatment of these major disorders, with a particular emphasis on their traditional uses, phytoconstituent contents, pharmacological properties, and modes of action. Active phytomolecules with therapeutic potential include cucurbitane triterpenoids, diosgenin, and limonoids (azadiradione and gedunin), which exhibit antidiabetic properties, with cucurbitane triterpenoids specifically activating Glucose Transporter Type 4 (GLUT4) translocation. Capsaicin and curcumin demonstrate anticancer activity by deactivating NF-κB and arresting the cell cycle in the G2 phase. Antimicrobial activities have been observed for piperine, reserpine, berberine, dictamnine, chelerythrine, and allitridin, with the latter two triggering bacterial cell lysis. Quercetin, catechin, and genistein exhibit anti-inflammatory properties, with genistein specifically suppressing CD8+ cytotoxic T cell function. Ginsenoside Rg1 and ginsenoside Rg3 demonstrate potential for treating cardiovascular diseases, with ginsenoside Rg1 activating PPARα promoter, and the PI3K/Akt pathway. In contrast, ternatin, tannins, and quercitrin exhibit potential in gastrointestinal disorders, with quercitrin regulating arachidonic acid metabolism by suppressing cyclooxygenase (COX) and lipoxygenase activity. Further studies are warranted to fully investigate the clinical therapeutic benefits of these plants and their phytoconstituents, as well as to elucidate their underlying molecular mechanisms of action.