Antidiabetic Naphthoquinones and Their Plant Resources in Thailand

Abstract

Diabetes mellitus is the seventh leading cause of death globally. Ninety percent of the diabetic population suffers from type-2 diabetes, which still needs an effective, safe and economical oral hypoglycemic therapy. Plants are rich sources of various therapeutic molecules. More than 400 medicinal plants of interesting phytochemical diversity have been reported for their antidiabetic potential. Naphthoquinones are a group of phytochemicals, which have a wide range of pharmacological potential, including antidiabetic activity. Naphthoquinones exert their antidiabetic effects through various mechanisms such as the inhibition of α-glucosidase and protein tyrosine phosphatase 1B, increased glucose uptake in myocytes and adipocytes via glucose transporter type 4 (GLUT4) and GLUT2 translocations, enhanced peroxisome proliferator-activated receptor gamma (PPARγ) ligand activity, and by normalizing carbohydrate metabolizing enzymes in the liver. Moreover, naphthoquinone inhibits adipogenesis by both upstream and downstream regulation to control obesity, which is one of the important risk factors for diabetes. Naturally occurring naphthoquinones, as well as their plant sources, are therefore of interest for exploring their antidiabetic potential. The present review aims to overview the antidiabetic potential of naphthoquinones and their plant resources in Thailand.

Seasonal Changes in the Metabolic Profiles and Biological Activity in Leaves of Diospyros digyna and D. rekoi “Zapote” Trees

“…Apropos of naphthoquinones, they are important secondary metabolites having therapeutic value that are commonly found in various Diospyros species [48]. In this context, the detection of the trigonelline–nicotinic acid combination, only detected in D. rekoi LEs was also interesting, considering that trigonelline, a pyridine alkaloid derived from nicotinic acid [49], has been reported to have a potent anti-diabetic effect, similar to naphthoquinones [50,51]. Approximately 100 trigonelline-forming plant species have been identified, including D. mollis [49,52].…”

Rhinacanthin-C Mediated Herb-Drug Interactions with Drug Transporters and Phase I Drug-Metabolizing Enzymes

“…Rhinacanthin-C is a major active constituent in R. nasutus, which has been commonly used in complementary therapy for various symptoms such as fever, fluid retention, hypertension, pneumonia, hepatitis, diabetes, and cancers (Siripong et al, 2006a,b;Horii et al, 2013;Shah et al, 2018). This compound is very likely to be taken concomitantly with several other drug substances, leading to herb-drug interaction issues (Horii et al, 2013;Shah et al, 2018). In the present study, we assessed the potential for rhinacanthin-C as a perpetrator in herb-drug (Gotoh et al, 2004;Panichayupakaranant et al, 2009).…”

Rhinacanthins‐rich extract and rhinacanthin C ameliorate oxidative stress and inflammation in streptozotocin‐nicotinamide‐induced diabetic nephropathy

“…RRE and RC significantly attenuated chronic renal damages, oxidative stress and inflammation in DN rats, which is in agreement with earlier studies that have proven that RRE from the leaves of R. nasutus or its active constituents displayed antioxidant, anti‐hyperglycemic, and anti‐inflammatory effects (Adam et al, ; Bhusal et al, ; Tewtrakul et al, ). Naphthoquinones isolated from R. nasutus have been reported as the bioactive molecules responsible for the biological function of the plant (Shah et al, ).…”

“…to lower blood glucose level, enhance glucose uptake and inhibit α-glucosidase enzyme (Shah, Keach, & Panichayupakaranant, 2018;. However, the F I G U R E 1 Chemical structures of the constituents in the rhinacanthins rich extract (RRE) from R. nasutus renoprotective role of R. nasutus rich extract (RRE) and RC against DN is still yet to be reported.…”

“…Furthermore, the use of medicinal plants as antidiabetic agents has been encouraged by the world health organization due to their limited safety concerns and their efficacy (Adam et al, ). R. nasutus rich extract and its major component RC has been reported to lower blood glucose level, enhance glucose uptake and inhibit α‐glucosidase enzyme (Shah, Keach, & Panichayupakaranant, ; Shah, Khalil, Ul‐Haq, & Panichayupakaranant, ). However, the renoprotective role of R. nasu tus rich extract (RRE) and RC against DN is still yet to be reported.…”