Gut microbiota in phytopharmacology: A comprehensive overview of concepts, reciprocal interactions, biotransformations and mode of actions

The dynamic and delicate interactions amongst intestinal microbiota, metabolome and metabolism dictates human health and disease. In recent years, our understanding of gut microbial regulation of intestinal immunometabolic and redox homeostasis have evolved mainly out of in vivo studies associated with high-fat feeding induced metabolic diseases. Techniques utilizing fecal transplantation and germ-free mice have been instrumental in reproducibly demonstrating how the gut microbiota affects disease pathogenesis. However, the pillars of modern drug discovery i.e. evidence-based pharmacological studies critically lack focus on intestinal microflora. This is primarily due to targeted in vitro molecular-approaches at cellular-level that largely overlook the etiology of disease pathogenesis from the physiological perspective. Thus, this review aims to provide a comprehensive understanding of the key notions of intestinal microbiota and dysbiosis, and highlight the microbiota-phytochemical bidirectional interactions that affects bioavailability and bioactivity of parent phytochemicals and their metabolites. Potentially by focusing on the three major aspects of gut microbiota i.e. microbial abundance, diversity, and functions, I will discuss phytochemical-microbiota reciprocal interactions, biotransformation of phytochemicals and plant-derived drugs, and pre-clinical and clinical efficacies of herbal medicine on dysbiosis. Additionally, in relation to phytochemical pharmacology, I will briefly discuss the role of dietary-patterns associated with changes in microbial profiles and review pharmacological study models considering possible microbial effects. This review therefore, emphasize on the timely and critically needed evidence-based phytochemical studies focusing on gut microbiota and will provide newer insights for future pre-clinical and clinical phytopharmacological interventions.

Acacia nilotica leaf improves insulin resistance and hyperglycemia associated acute hepatic injury and nephrotoxicity by improving systemic antioxidant status in diabetic mice

ETHNOPHARMACOLOGICAL RELEVANCE

Acacia nilotica (L.) Delile is used as a traditional anti-diabetic remedy in Bangladesh, Pakistan, Egypt, Nigeria and is mentioned in Ayurveda as well.

AIM

The objective of the study was to evaluate the ethnomedicinal claim of A. nilotica leaf (ANL) extract for its efficiency in ameliorating diabetic complications.

MATERIALS AND METHODS

ANL was orally administrated (50 and 200mg/kg) to alloxanized mice (blood glucose > 200mg/dL) for 20d. Parameters of glucose metabolism, hepatotoxicity, hyperlipidemia and nephrotoxicity were measured with emphasis on elevated oxidative stress. ANL was chemically characterized using GC-MS. Further, docking studies were employed to predict molecular interactions.

RESULTS

ANL lowered (65%, P< 0.001) systemic glucose load in diabetic mice, which was otherwise 398% higher than control. ANL lowered (35%) insulin resistance, without any significant effect on insulin sensitivity (P> 0.05). Anti-hyperglycemic properties of ANL was further supported by lowering of HbA1c (34%; P< 0.001) and improved glucose utilization (OGTT). Overall diabetic complications were mitigated as reflected by lowered hepatic (ALT, AST) and renal (creatinine, BUN) injury markers and normalization of dyslipidemia. Elevated systemic oxidative stress was lowered by increased catalase and peroxidase activities in liver, kidney and skeletal muscle, resulting in 32% decrease of serum MDA levels. Apart from high phenolic and flavonoid content, tocopherol, catechol and β-sitosterol, identified in ANL, demonstrated substantial binding affinity with Nrf2 protein (5FNQ) reflecting possible crosstalk with intracellular antioxidant defense pathways.

CONCLUSION

The present study revealed the potentials of A. nilotica to alleviate diabetes-related systemic complications by limiting oxidative stress which justified the ethnopharmacological antidiabetic claim.

Peroxidase production and ligninolytic potentials of fresh water bacteria Raoultella ornithinolytica and Ensifer adhaerens

Interest in novel ligninolytic bacteria has remained topical due to, in part, the maneuverability of the bacterial genome. Conversely, the fungal genome lacks the dexterity for similar maneuverability thus, posing challenges in the fungal enzyme yield optimization process. Some impact of this situation includes the inability to commercialize the bio-catalytic process of lignin degradation by fungi. Consequently, this study assessed some fresh water bacteria isolates for ligninolytic and peroxidase properties through the utilization and degradation of model lignin compounds (guaiacol and veratryl alcohol) and the decolourization of selected ligninolytic indicator dyes; Azure B (AZB), Remazol Brilliant Blue R (RBBR) and Congo Red (CR). Bacterial strains with appreciable ligninolytic and peroxidase production potentials were identified through 16S rDNA sequence analysis and the nucleotide sequences deposited in the GenBank. About 5 isolates were positive for the degradation of both guaiacol (GA) and veratryl alcohol (VA) thus, accounting for about 17% of the test isolates. Similarly, AZB, RBBR and CR were respectively decolorized by 3, 2 and 5 bacterial strains thus, accounting for 10%, 7% and 17% of the test isolates. Two of the test bacterial strains were able to decolourize AZB, RBBR and CR respectively and these bacterial strains were identified as Raoultella ornithinolytica OKOH-1 and Ensifer adhaerens NWODO-2 with respective accession numbers as KX640917 and KX640918. Upon quantitation of the peroxidase activities; 5250 ± 0.00 U/L was recorded against Raoultella ornithinolytica OKOH-1 and 5833 ± 0.00 U/L against Ensifer adhaerens NWODO-2. The ligninolytic and dye decolourization properties of Raoultella ornithinolytica OKOH-1 and Ensifer adhaerens NWODO-2 marks for novelty particularly, as dyes with arene substituents were decolourized. Consequently, the potentials for the industrial applicability of these test bacterial strains abound as there is a dearth of information on organisms with such potentials.

Propyl gallate/cyclodextrin supramolecular complexes with enhanced solubility and radical scavenging capacity

This study prepared and investigated the inclusion complexes of propyl gallate (PG) with beta-cyclodextrin (β-CD) and its water-soluble derivatives dimethyl-beta-cyclodextrin (DM-β-CD), hydroxypropyl-beta-cyclodextrin (HP-β-CD), and sulfobutylether-beta-cyclodextrin (SBE-β-CD). Phase solubility studies indicated that the formed complexes were in 1:1 stoichiometry. FT-IR, PXRD, DSC, ¹H-NMR, ROESY-NMR, and SEM analysis results confirmed the formation of the complexes. The NMR results indicated that the aromatic ring of PG was embedded into the CD cavity. The aqueous solubility of PG was markedly improved, and that of the PG/DM-β-CD complex increased by 365.3 times. In addition, the results of the antioxidant activity assay showed that the hydroxyl radical and superoxide radical scavenging capacities of the complexes increased by 3-11 times and 1-6.5 times, respectively, compared with those of PG under the same concentration. Therefore, CD/PG inclusion complexes with improved solubility and radical scavenging capacity can be used as water-soluble antioxidants in the food industry.

Effect of Amalaki rasayana on DNA damage and repair in randomized aged human individuals

ETHNOPHARMACOLOGICAL RELEVANCE

Preparations from Phyllanthus emblica called Amalaki rasayana is used in the Indian traditional medicinal system of Ayurveda for healthy living in elderly. The biological effects and its mechanisms are not fully understood. Since the diminishing DNA repair is the hallmark of ageing, we tested the influence of Amalaki rasayana on recognized DNA repair activities in healthy aged individuals.

METHODS

Amalaki rasayana was prepared fresh and healthy aged randomized human volunteers were administrated with either rasayana or placebo for 45 days strictly as per the traditional text. The DNA repair was analyzed in peripheral blood mononuclear cells before and after rasayana administration and after 45 days post-rasayana treatment regimen. UVC-induced DNA strand break repair (DSBR) based on extent of DNA unwinding by fluorometric analysis, nucleotide excision repair (NER) by flow cytometry and constitutive base excision repair (BER) by gap filling method were analyzed.

RESULTS

Amalaki rasayana administration stably maintained/enhanced the DSBR in aged individuals. There were no adverse side effects. Further, subjects with different body mass index showed differential DNA strand break repair capacity. No change in unscheduled DNA synthesis during NER and BER was observed between the groups.

CONCLUSION

Intake of Amalaki rasayana by aged individuals showed stable maintenance of DNA strand break repair without toxic effects. However, there was no change in nucleotide and base excision repair activities. Results warrant further studies on the effects of Amalaki rasayana on DSBR activities.

Guaraná (Paullinia cupana) seeds: Selective supercritical extraction of phenolic compounds

Approximately 70% of the Brazilian production of guaraná (Paullinia cupana) seeds is absorbed by the beverage industries. Guaraná has several pharmacological properties: energy stimulant, antimicrobial, chemoprophylactic, antigenotoxic, antidepressive, anxiolytic, and anti-amnesic effects. Supercritical carbon dioxide extraction of bioactive compounds from guaraná seeds was carried out and optimized by an orthogonal array design (OA9(3(4))). The factors/levels studied were: modifier(s) (ethanol and/or methanol), extraction time (20, 40, and 60min), temperature (40, 50, and 60°C), and pressure (100, 200, and 300bar). The statistical design was repeated with increasing proportions of modifiers. The percentage of modifier used was proportional to the amount of polar compounds extracted. The best conditions for the supercritical extraction, based on the content of polyphenols, epicatechin/catechin quantification, yield and operating cost, proved to be: 40% ethanol:methanol during 40min, under 40°C, and 100bar. The temperature had a significant effect on the total phenolic content.

Changes of major tea polyphenols and production of four new B-ring fission metabolites of catechins from post-fermented Jing-Wei Fu brick tea

HPLC analysis of samples from four major fermentation procedures of Jing-Wei Fu brick tea showed that the level of major tea catechins epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) dropped increasingly to about 1/3 in the final product. Phytochemical study of the final product led to the discovery of four new B-ring fission metabolites of catechins (BRFCs) Fuzhuanin C-F (1-4) together with three known BRFCs (5-7), six known catechins (8-13), five simple phenols (14-18), seven flavones and flavone glycosides (19-25), two alkaloids (26, 27), three triterpenoids (28-30) and one steroid (31). The structures were elucidated by spectroscopic methods including 1D and 2D NMR, LC-HR-ESI-MS, IR, and CD spectra. Five compounds (16-18, 28, 29) were reported for the first time in tea. Possible pathways for the degradation of major tea catechins and the generation of BRFCs were also provided.