Safety assessment of the ethanolic extract of Gongronema latifolium Benth. leaves: a 90-day oral toxicity study in Sprague Dawley rats

Nutraceutical management of metabolic syndrome as a palliative and a therapeutic to coronavirus disease (COVID) crisis

The global market for medicinal plants and herbs is on the increase due to their desirability, efficacy, and less adverse effects as complementary and alternative medications to the orthodox pharmaceuticals, perhaps due to their natural components and qualities. Metabolic syndromes are managed with changes in diet, exercise, lifestyle modifications and the use of pharmacological agents. Plants are now known to have potent antioxidant and cholinergic activities which are relevant to the management of several metabolic syndromes, which are unfortunately, co-morbidity factors in the coronavirus disease crisis. This review will focus on the biological activities of some plant products used as complementary and alternative medicines in the management of metabolic syndromes, and on their reported antiviral, antithrombotic, angiotensin-converting enzyme inhibitory properties, which are integral to their usage in the management of viral infections and may give an avenue for prophylactic and therapeutics especially in the absence of vaccines/formulated antiviral therapies.

Identification of potential inhibitors of cholinergic and β-secretase enzymes from phytochemicals derived from Gongronema latifolium Benth leaf: an integrated computational analysis

Neurodegenerative disorders (NDDs) are associated with increased activities of the brain acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and β-secretase enzyme (BACE1). Inhibition of these enzymes affords therapeutic option for managing NDDs such as Alzheimer's disease (AD) and Parkinson's disease (PD). Although, Gongronema latifolium Benth (GL) has been widely documented in ethnopharmacological and scientific reports for the management of NDDs, there is paucity of information on its underlying mechanism and neurotherapeutic constituents. Herein, 152 previously reported Gongronema latifolium derived-phytochemicals (GLDP) were screened against hAChE, hBChE and hBACE-1 using molecular docking, molecular dynamics (MD) simulations, free energy of binding calculations and cluster analysis. The result of the computational analysis identified silymarin, alpha-amyrin and teraxeron with the highest binding energies (-12.3, -11.2, -10.5 Kcal/mol) for hAChE, hBChE and hBACE-1 respectively as compared with those of the reference inhibitors (-12.3, -9.8 and - 9.4 for donepezil, propidium and aminoquinoline compound respectively). These best docked phytochemicals were found to be orientated in the hydrophobic gorge where they interacted with the choline-binding pocket in the A-site and P-site of the cholinesterase and subsites S1, S3, S3' and flip (67-75) residues of the pocket of the BACE-1. The best docked phytochemicals complexed with the target proteins were stable in a 100 ns molecular dynamic simulation. The interactions with the catalytic residues were preserved during the simulation as observed from the MMGBSA decomposition and cluster analyses. The presence of these phytocompounds most notably silymarin, which demonstrated dual high binding tendencies to both cholinesterases, were identified as potential neurotherapeutics subject to further investigation.

Inhibition mechanism of alpha-amylase, a diabetes target, by a steroidal pregnane and pregnane glycosides derived from Gongronema latifolium Benth

Alpha-amylase is widely exploited as a drug target for preventing postprandial hyperglycemia in diabetes and other metabolic diseases. Inhibition of this enzyme by plant-derived pregnanes is not fully understood. Herein, we used in vitro, in silico, and in vivo studies to provide further insights into the alpha-amylase inhibitory potential of selected pregnane-rich chromatographic fractions and four steroidal pregnane phytochemicals (SPPs), viz: marsectohexol (P1), 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→14)-β-D-oleandropyranosyl]-11,12-di-O-tigloyl-17β-marsdenin (P2), 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl]-17β-marsdenin (P3), and 3-O-[6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-canaropyranosyl]-17β-marsdenin (P4) derived from Gongronema latifolium Benth. The results revealed that the SPPs source pregnane-rich chromatographic fractions and the SPPs (P1–P4) exhibited inhibitory potential against porcine pancreatic alpha-amylase in vitro. Compounds P1 and P2 with IC50 values 10.01 and 12.10 µM, respectively, showed greater inhibitory potential than the reference acarbose (IC50 = 13.47 µM). Molecular docking analysis suggests that the SPPs had a strong binding affinity to porcine pancreatic alpha-amylase (PPA), human pancreatic alpha-amylase (HPA), and human salivary alpha-amylase (HSA), interacting with the key active site residues through an array of hydrophobic interactions and hydrogen bonds. The strong interactions of the SPPs with Glu233 and Asp300 residues may disrupt their roles in the acid-base catalytic mechanism and proper orientation of the polymeric substrates, respectively. The interactions with human pancreatic amylase were maintained in a dynamic environment as indicated by the root mean square deviation, radius of gyration, surface accessible surface area, and number of hydrogen bonds computed from the trajectories obtained from a 100-ns molecular dynamics simulation. Key loop regions of HPA that contribute to substrate binding exhibited flexibility and interaction potential toward the compounds as indicated by the root mean square fluctuation. Furthermore, P1 significantly reduced blood glucose levels and area under the curve in albino rats which were orally challenged with starch. Therefore, Gongronema latifolium and its constituent SPPs may be exploited as inhibitors of pancreatic alpha-amylase as an oral policy for impeding postprandial blood glucose rise.

Toxicological assessment of enzyme-treated Zizania latifolia extract: Oral toxicology and genotoxicity in rats

Zizania latifolia Turcz. has long been used as a food source in Southeast Asia. The grains, stems, and leaves of Z. latifolia and its major component, tricin, have also been studied to determine their biological activities. Previously, we hydrolyzed the aerial part of Z. latifolia using an enzyme mixture to maximize the tricin content of the Z. latifolia extract. However, the safety of enzyme-treated Z. latifolia extract (ETZL; DermaNiA™) has not yet been determined. In this study, we performed an in vivo 90-day repeated-dose evaluation and genotoxicity study to assess the toxicological potential of ETZL. EZTL did not exhibit genotoxicity in the bacterial reverse mutation test, in vitro chromosomal aberration assay, or in vivo micronucleus test. Moreover, no changes in body weight or hematological and serum biological parameters were observed in male or female rats under high-dose EZTL treatment (5000 mg/kg body weight (bw)/day) for 90 days with a 4-week recovery period. Significant changes were noted in the forestomach, kidneys, and adrenal glands in the test groups, but these changes, or tendency for recovery, were not observed in the recovery group. Based on these data, the no adverse effect level was determined to be 1250 mg/kg bw/day in rats.

A 90-Day Oral Toxicity Study of an Ethanolic Root Extract of Caesalpinia bonduc (L.) Roxb. in Wistar Rats

Background

Plant medicine is the oldest form of health care known to mankind; hence, studies on their safety for use are essential for the control of adverse drug effects. In Benin, Caesalpinia bonduc is one of many medicinal plants used as aphrodisiac, and for treatment of various ailments including prostatic hyperplasia. Despite its numerous ethnomedicinal benefits, toxicological information associated with its chronic use is currently limited.

Objective

The present study therefore assessed the toxicity of an ethanolic root extract of Caesalpinia bonduc in Wistar rats.

Methods

Caesalpinia bonduc root extract was administered by oral gavage at doses of 31.25, 125, and 500 mg/kg/day for 90 days to male Wistar rats, after which body weight changes, food consumption, urinary parameters, hematological and blood biochemical parameters, organ weights changes, gross pathology, and histopathology of vital organs were assessed.

Results

There were no death or abnormal clinical signs, no significant changes in body weight gain or urinary parameters, and no changes in necropsy and histopathology findings of vital organs associated with extract treatment. However, some indices such as erythrocytes, total cholesterol, and aspartate amino transferase increased in rats treated with high doses of the extract, as well as relative weight of testes, followed by a decrease in food intake and prostate relative weight.

Conclusion

The results indicate that an ethanolic root extract of Caesalpinia bonduc does not cause significant adverse effects and suggest its tolerability up to 500 mg/kg for daily administration of 90 days.

Twenty-four-week oral dosing toxicities of Herba Siegesbeckiae in rats

BACKGROUND

Herba Siegesbeckiae (HS), the dried aerial parts of Siegesbeckia orientalis L., S. pubescens Makino, or S. glabrescens Makino, is traditionally used for treating chronic diseases in China. However, there is no information about the chronic toxicity of HS. The objective of this study is to evaluate the 24-week oral dosing toxicities of HS aqueous extract (HSE) in rats.

METHODS

S. orientalis-originated HS was reflux-extracted with distilled water. Sprague-Dawley rats were randomly divided into four groups, with 10 males and 10 females in each group. The rats were intragastrically administered with HSE at 5, 1.67 and 0.56 g/kg (experimental groups) or an equal volume of distilled water (control group), 6 days a week, for 24 weeks. The high dose of HSE (5 g/kg) was its maximum tolerated dose. Body weight was recorded every 2 days during the experimental period. Chemical, hematological and histopathological parameters, as well as organ weights, were measured at the end of the experiment.

RESULTS

Decreased body weight gain; increased liver and lung relative weights; histopathological alterations in liver and lung tissues; elevated serum levels of alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase and lactate dehydrogenase were found after HSE treatments. In liver tissues, HSE treatment upregulated levels of three pro-inflammatory cytokines: IL-6, IL-1β and TNF-α. In lung tissues, HSE treatment caused oxidative stress and activated mitogen-activated protein kinases (MAPKs).

CONCLUSION

Long-term oral administration of HSE caused toxicities in rats evidenced by decreased body weight gain, as well as liver and lung damage. Treatment-induced oxidative stress, inflammation and MAPK activation are involved in HSE's toxicities. Caution should be taken when using HS to treat chronic diseases.