Tamarixetin 3-O-β-d-Glucopyranoside from Azadirachta indica Leaves: Gastroprotective Role through Inhibition of Matrix Metalloproteinase-9 Activity in Mice

Quercetin as one of the most abundant represented biological valuable plant components with remarkable chemoprotective effects - A review

As a consequence of environmental quality changes as well as changes in our population's lifestyle, there is rapidly increasing variability and many so-called lifestyle disorders, allergies, and food intolerances (also known as non-allergic food hypersensitivity). Unhealthy eating practices, an inappropriate food composition with an excessive energy intake, a high intake of saturated fats, simple sugars, and salt, as well as an inadequate intake of fibre, vitamins, and substances with preventive effects (such as antioxidants), are some of the factors causing this detrimental phenomenon. Enhanced consumption of plant foods rich in valuable secondary metabolites such as phenolic acids and flavonoids with the benefit on human health, food research focused on these components, and production of foods with declared higher content of biologically active and prophylactic substances are some ways how to change and improve this situation. A unique class of hydroxylated phenolic compounds with an aromatic ring structure are called flavonoids. One unique subclass of flavonoids is quercetin. This phytochemical naturally takes place in fruits, vegetables, herbs, and other plants. Quercetin and its several derivates are considered to be promising substances with significant antidiabetic, antibacterial, anti-inflammatory, and antioxidant effects, which could also act preventively against cardiovascular disease, cancer, or Alzheimer's disease.

Research Progress of Tamarixetin and its Glycosides

Tamarixetin and its glycosides are widely distributed in natural plants, and they are also natural flavonoid derivatives of quercetin. Its main pharmacological effects include antioxidant, antiinflammatory, antiviral, anticancer, cardiovascular effects, etc. The pharmacokinetics showed that the distribution of direct absorption differed from that of biosynthesis. At the same time, research shows that tamarixetin is safe to use because it has little self-toxicity. In this paper, 181 articles on tamarixetin published from 1976 to 2023 are obtained from PubMed, China Knowledge Base Database, Wanfang Data, and other electronic databases. Tamarixetin is searched based on keywords, and 121 articles remain. Transformation synthesis, pharmacokinetics, pharmacological action, and structureactivity relationship of tamarixetin were reviewed.

Attenuative effects of tamarixetin against polystyrene microplastics-induced hepatotoxicity in rats by regulation of Nrf-2/Keap-1 pathway

Polystyrene microplastics (PS-MPs) are environmental contaminants due to their potential to induce damages in multiple organs specifically liver. Tamarixetin (TMT) is a naturally occurring flavonoid present in Tamarix ramosissima plant that exhibits multiple pharmacological properties. Therefore, the present research was designed to evaluate the palliative role of TMT against PS-MPs instigated liver dysfunction in rats. The exposure to PS-MPs reduced the expressions of nuclear factor erythroid 2-related factor 2 and antioxidant genes, while increasing the expression of Kelch-like ECH-associated protein 1. PS-MPs exposed rats exhibited considerably (p < .05) higher alkaline phosphatase (ALP), aspartate aminotransferase (AST) as well as alanine aminotransferase (ALT) contents. Additionally, PS-MPs treatment resulted in a notable decrease in anti-oxidants activity, that is, glutathione S-transferase (GST), superoxide dismutase (SOD), heme oxygenase-1 (HO-1), glutathione reductase (GSR), glutathione peroxidase (GPx), catalase (CAT) and glutathione (GSH) content, whereas upregulating reactive oxygen species (ROS) and malondialdehyde (MDA) contents. Moreover, PS-MPs intoxication noticeably increased (p < .05) the inflammatory indices (interleukin-1ß [IL-1ß], nuclear factor kappa B [NF-κB], interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α] levels, and cyclooxygenase-2 [COX-2] activity). Besides, Caspase-3 and Bax expressions were upregulated and Bcl-2 expression was decreased after PS-MPs exposure. Additionally, the histomorphological examination revealed notable hepatic damage in PS-MPs treated group. However, TMT treatment substantially (p < .05) recovered all the PS-MPs-induced damages and histopathological changes. Taken together, it can be deduced that TMT might be used as a pharmacological agent to ameliorate hepatic damage.

Glucosidase inhibitor, Nimbidiol ameliorates renal fibrosis and dysfunction in type-1 diabetes

Diabetic nephropathy is characterized by excessive accumulation of extracellular matrix (ECM) leading to renal fibrosis, progressive deterioration of renal function, and eventually to end stage renal disease. Matrix metalloproteinases (MMPs) are known to regulate synthesis and degradation of the ECM. Earlier, we demonstrated that imbalanced MMPs promote adverse ECM remodeling leading to renal fibrosis in type-1 diabetes. Moreover, elevated macrophage infiltration, pro-inflammatory cytokines and epithelial‒mesenchymal transition (EMT) are known to contribute to the renal fibrosis. Various bioactive compounds derived from the medicinal plant, Azadirachta indica (neem) are shown to regulate inflammation and ECM proteins in different diseases. Nimbidiol is a neem-derived diterpenoid that is considered as a potential anti-diabetic compound due to its glucosidase inhibitory properties. We investigated whether Nimbidiol mitigates adverse ECM accumulation and renal fibrosis to improve kidney function in type-1 diabetes and the underlying mechanism. Wild-type (C57BL/6J) and type-1 diabetic (C57BL/6-Ins2^Akita/J) mice were treated either with saline or with Nimbidiol (0.40 mg kg^-1 d^-1) for eight weeks. Diabetic kidney showed increased accumulation of M1 macrophages, elevated pro-inflammatory cytokines and EMT. In addition, upregulated MMP-9 and MMP-13, excessive collagen deposition in the glomerular and tubulointerstitial regions, and degradation of vascular elastin resulted to renal fibrosis in the Akita mice. These pathological changes in the diabetic mice were associated with functional impairments that include elevated resistive index and reduced blood flow in the renal cortex, and decreased glomerular filtration rate. Furthermore, TGF-β1, p-Smad2/3, p-P38, p-ERK1/2 and p-JNK were upregulated in diabetic kidney compared to WT mice. Treatment with Nimbidiol reversed the changes to alleviate inflammation, ECM accumulation and fibrosis and thus, improved renal function in Akita mice. Together, our results suggest that Nimbidiol attenuates inflammation and ECM accumulation and thereby, protects kidney from fibrosis and dysfunction possibly by inhibiting TGF-β/Smad and MAPK signaling pathways in type-1 diabetes.

Protective Effect of Anwulignan on Gastric Injury Induced by Indomethacin in Mice

Anwulignan (AN) is a monomer lignan from Schisandra sphenanthera Rehd. et Wits (Schisandra sphenanthera fructus, Schisandra sphenanthera). The protective effect of AN against the indomethacin (IND)-induced gastric injury to mice and the related mechanism of action was investigated in this study. The effect of AN was mainly assessed by observing the gastric tissue morphology, gastric ulcer index (GUI), ulcer inhibition rate (UIR), gastric juice volume (GJV) and pH value. Chemical colorimetry, immunofluorescence, ELISA, and Western blot were used to detect related factors in the gastric tissue. The results showed that AN reduced the GUI, increased the UIR, inhibited the GJV, and increased the gastric pH value. AN significantly increased cyclooxygenase-1, cyclooxygenase-2, and prostaglandin E2 expression levels in the gastric tissue, activated nuclear factor (erythroid-derived 2)-like 2 (Nrf2), increased heme oxygenase-1 expression, enhanced the activity of superoxide dismutase and glutathione peroxidase, and decreased the malondialdehyde content. AN reduced the phosphorylation of nuclear factor-κ gene binding (NF-κB) p65 and its nuclear translocation, the key protein of NF-κB signaling pathway in the gastric tissue, and the content of the pathway downstream signaling molecules, including interleukin-6, interleukin-1β, and tumor necrosis factor-α, to play an anti-inflammatory role. AN inhibited the downstream signals B-cell lymphoma 2-associated x protein and cleaved caspase-3 in gastric tissue, and activated B-cell lymphoma 2, to play an antiapoptotic role, which were further verified by Hoechst staining. Therefore, AN has a significant protection against the gastric injury induced by IND in mice, and the mechanism may be concerned in its activation of Nrf2, inhibition of NF-κB signaling pathway, and anti-apoptotic effect. SIGNIFICANCE STATEMENT: Anwulignan (AN) significantly reduced the indomethacin-induced gastric injury in mice, and its antioxidation, anti-inflammation, and antiapoptosis were considered to be involve in the effect, suggesting that AN should be a potential drug or food supplement for gastric injury induced by indomethacin.

Tamarixetin Abrogates Adipogenesis Through Inhibiting p300/CBP-Associated Factor Acetyltransferase Activity in 3T3-L1 Preadipocyte Cells

Tamarixetin (TX) is an O-methylated flavonoid naturally derived from quercetin. TX has bioactive properties; however, whether it shows antilipogenic activity remains unknown. Therefore, in the present study, we aimed to determine the antilipogenic effects of TX using 3T3-L1 adipocytes. The 3T3-L1 adipocytes were cultured in a differentiation medium with or without TX. Lipid accumulation was diminished and the mRNA expression of lipogenesis-related genes was decreased following TX treatment. We found that TX exhibited antilipogenic effects by inhibiting the expression of p300/CBP-associated factor (pCAF), a histone acetyltransferase, as confirmed by pCAF knockdown. Furthermore, TX inhibited both pCAF expression and its activity, thereby reducing the total acetylation level of nonhistone and histone proteins. Finally, TX decreased the expression of CCAAT/enhancer-binding protein alpha and beta (CEBPα and CEBPβ), and peroxisome proliferator-activated receptor γ along with pCAF expression during adipogenesis of 3T3-L1 cells in a time-dependent manner. Collectively, our findings suggest that TX is a potent antilipogenic agent derived from natural products and may be used as a pCAF inhibitor.

Melatonin rescues swim stress induced gastric ulceration by inhibiting matrix metalloproteinase-3 via down-regulation of inflammatory signaling cascade

AIM

This study investigated the link between forced swim induced acute gastric ulceration, inflammation and MMP-3 along with the possible mechanism of protective efficacy of melatonin.

MAIN METHODS

We distributed Balb/c mice into four different groups. Group 1 and 2 were given PBS gavage. Group 3 and 4 were given melatonin (60 mg/kg b.wt.) and omeprazole (25 mg/kg b.wt.), respectively, an hour prior to forced swim. Ulcer index, tissue histology, immunohistochemistry, protein carbonylation, lipid peroxidation, Myeloperoxidase, Zymography, Western blotting, reactive oxygen species (ROS), mitochondrial dehydrogenase, mitochondrial transmembrane potential and bioinformatical analysis were performed.

KEY FINDINGS

Our data revealed that gastric ulceration due to forced swim stress is responsible for overproduction of ROS, which may be a prime reason for mitochondrial dysfunction and induction of apoptosis via activation of Caspase-3. ROS is also responsible for p38 phosphorylation which in turn increases the activity of MMP-3 in ulcerated milieu, along with the oxidation of proteins, peroxidation of lipids and altered expression patterns of heat shock protein (HSP)-70. Melatonin is shown to reduce the inflammatory burden in gastric milieu and offers gastroprotection by binding to the active site of MMP-3; thereby inhibiting its activity, as suggested by in silico studies. Melatonin also inhibits the downregulation of HSP-70 and activates p38 dephosphorylation and thereby, it rescues gastric mucosal cells from stress-induced ulceration.

SIGNIFICANCE

Our findings suggest that, melatonin imparts its gastroprotective effect by down-regulating the activation of MAPK-ERK pathway along with binding to the active site of MMP-3.

Biosynthesis of bioactive tamarixetin in recombinant Escherichia coli

Tamarixetin, a monomethylated derivative of quercetin, has been reported to possess many important biological activities. In the present study, a whole cell biotransformation system was used for regiospecific methylation of quercetin to produce 4'-O-methylated quercetin (tamarixetin) using methyltransferase from Streptomyces sp. KCTC 0041BP in Escherichia coli Bl21 (DE3). Its production was enhanced by adding a plasmid containing S-adenosine-l-methionine (SAM) synthase from E. coli K12 (MetK) with subsequent feeding of l-methionine and glycerol in the culture. The best condition produced ∼279 μM (88.2 mg/L) of tamarixetin. The biological activity of tamarixetin was tested and compared with quercetin, 7-O-methylated quercetin, and 3-O-methylated quercetin. Results showed that the growth of all tested cancer cell lines (AGS, B16F10, C6, and HeLa) were inhibited by tamarixetin more effectively than other methylated derivatives of quercetin or quercetin. Tamarixetin also exhibited the best antimelanogenic activity among all compounds tested.

Unraveling Plant Natural Chemical Diversity for Drug Discovery Purposes

The screening and testing of extracts against a variety of pharmacological targets in order to benefit from the immense natural chemical diversity is a concern in many laboratories worldwide. And several successes have been recorded in finding new actives in natural products, some of which have become new drugs or new sources of inspiration for drugs. But in view of the vast amount of research on the subject, it is surprising that not more drug candidates were found. In our view, it is fundamental to reflect upon the approaches of such drug discovery programs and the technical processes that are used, along with their inherent difficulties and biases. Based on an extensive survey of recent publications, we discuss the origin and the variety of natural chemical diversity as well as the strategies to having the potential to embrace this diversity. It seemed to us that some of the difficulties of the area could be related with the technical approaches that are used, so the present review begins with synthetizing some of the more used discovery strategies, exemplifying some key points, in order to address some of their limitations. It appears that one of the challenges of natural product-based drug discovery programs should be an easier access to renewable sources of plant-derived products. Maximizing the use of the data together with the exploration of chemical diversity while working on reasonable supply of natural product-based entities could be a way to answer this challenge. We suggested alternative ways to access and explore part of this chemical diversity with in vitro cultures. We also reinforced how important it was organizing and making available this worldwide knowledge in an "inventory" of natural products and their sources. And finally, we focused on strategies based on synthetic biology and syntheses that allow reaching industrial scale supply. Approaches based on the opportunities lying in untapped natural plant chemical diversity are also considered.

Phytochemicals targeting matrix metalloproteinases regulating tissue degradation in inflammation and rheumatoid arthritis

PURPOSE

Matrix metalloproteinases, zinc dependent proteolytic enzymes, have significant implications in extracellular matrix degradation associated with tissue damage in inflammation and Rheumatoid arthritis. Numerous orchestrated pathways affects instigation and blockade of metalloproteinases as well as various factors that increase the expression of MMPs including inflammatory cytokines, hormones and growth factors. Direct inhibition of these proteolytic enzymes or modulation of these pathways can provide protection against tissue destruction in inflammation and rheumatoid arthritis. Inclination towards use of plant derived phytochemicals to prevent tissue damage has been increasing day by day. Diversity of phytochemicals have been known to directly inhibit metalloproteinases. Hence, thorough knowledge of phytochemicals is very important in novel drug discovery.

METHODS

Present communication evaluates various classes of phytochemicals, in effort to unveil the lead molecules as potential therapeutic agents, for prevention of MMPs mediated tissue damage in inflammation and rheumatoid arthritis. Data have been analyzed through different search engines.

RESULTS

Numerous phytochemicals have been studied for their role as MMPs inhibitors which can be processed further to develop into useful drugs for the treatment of inflammation and rheumatoid arthritis.

CONCLUSION

In search of new drugs, phytochemicals like flavonoids, glycosides, alkaloids, lignans & terpenes offer a wide canvas to develop into valuable forthcoming medicaments.

Study on Pharmacokinetic and Bioavailability of Tamarixetin after Intravenous and Oral Administration to Rats

In this study, a sensitive and reliable HPLC-MS/MS method was established to quantify tamarixetin in rat plasma. This method was then applied to research on the pharmacokinetic and bioavailability of tamarixetin after intravenous and oral administration in vivo. The study was performed on CORTECS C₁₈ column (4.6 mm × 150 mm, 2.7 μm) using mobile phase composed of methanol-water-formic acid (85 : 15 : 0.1, v/v) at a flow rate of 0.3 mL/min by a tandem mass system with an electrospray ionization (ESI) source in the negative multiple-reaction monitoring (MRM) mode. The calibration curves showed good linearity in the range of 5–4000 ng/mL. The intra- and interday precision of tamarixetin was less than 8.7% and 4.8%, respectively, and accuracy was within ±9.5%. Extraction recovery (91.4–100.0%) and matrix effect (99.4–107.4%) met the guidelines published by regulatory authorities. The oral bioavailability of tamarixetin was 20.3 ± 12.4%.

Tamarixetin protects against cardiac hypertrophy via inhibiting NFAT and AKT pathway

Cardiac hypertrophy is a compensatory response in reaction to mechanical load that reduces wall stress by increasing wall thickness. Chronic hypertrophic remodeling involves cardiac dysfunction that will lead to heart failure and ultimately death. Studies have been carried out on cardiac hypertrophy for years, whereas the mechanisms have not been well defined. Tamarixetin (TAM), a natural flavonoid derivative of quercetin, have been demonstrated possessing anti-oxidative and anti-inflammatory effects on multiple diseases. However, little is known about the function of TAM on the development of cardiac hypertrophy. Here, we found TAM could alleviate pressure-overload-induced cardiac hypertrophy in transverse aortic constriction (TAC) mouse model, assessed by ventricular weight/body weight, lung weight/body weight, echocardiographic parameters, as well as myocyte cross-sectional area and the expression of ANP, BNP and Myh7. In vitro, TAM showed a dose dependent inhibitory effect on phenylephrine-induced hypertrophy in H9c2 cardiomyocytes. Furthermore, TAM reversed cardiac remodeling of stress overloaded heart by suppressing apoptosis and the expression of fibrotic-related genes, reduced oxidative stress and ROS production both in vivo and in vitro. In addition, TAM could negatively modulate TAC-induced nuclear translocation of NFAT and the activation of PI3K/AKT signaling pathways. Therefore, these data indicate for the first time that TAM has a protective effect on experimental cardiac hypertrophy and might be a novel candidate for the treatment of cardiac hypertrophy in clinic.

Inhibition of a Snake Venom Metalloproteinase by the Flavonoid Myricetin

Most of the snakebite envenomations in Central and South America are caused by species belonging to Bothrops genus. Their venom is composed mainly by zinc-dependent metalloproteinases, responsible of the hemorrhage characteristic of these envenomations. The aim of this study was to determine the inhibitory ability of ten flavonoids on the in-vitro proteolytic activity of Bothrops atrox venom and on the hemorrhagic, edema-forming and myonecrotic activities of Batx-I, the most abundant metalloproteinase isolated from this venom. Myricetin was the most active compound, exhibiting an IC 50 value of 150 μ M and 1021 μ M for the inhibition of proteolytic and hemorrhagic activity, respectively. Independent injection experiments, with a concentration of 1600 μ M of myricetin administered locally, immediately after toxin injection, demonstrated a reduction of 28 ± 6 % in the hemorrhagic lesion. Additionally, myricetin at concentrations 800, 1200 and 1600 μ M promoted a reduction in plasma creatine kinase activity induced by Batx-I of 21 ± 2 % , 60 ± 5 % and 63 ± 2 % , respectively. Molecular dynamics simulations coupled with the adaptive biasing method suggest that myricetin can bind to the metalloproteinase active site via formation of hydrogen bonds between the hydroxyl groups 3', 4' and 5' of the benzyl moiety and amino acid Glu143 of the metalloproteinase. The hydroxyl substitution pattern of myricetin appears to be essential for its inhibitory activity. Based on this evidence, myricetin constitutes a candidate for the development of inhibitors to reduce local tissue damage in snakebite envenomations.

Scabiosa Genus: A Rich Source of Bioactive Metabolites

The genus Scabiosa (family Caprifoliaceae) is considered large (618 scientific plant names of species) although only 62 have accepted Latin binominal names. The majority of the Scabiosa species are widely distributed in the Mediterranean region and some Scabiosa species are used in traditional medicine systems. For instance, Scabiosa columbaria L. is used traditionally against diphtheria while S. comosa Fisch. Ex Roem. and Schult. is used in Mongolian and Tibetan traditional medical settings to treat liver diseases. The richness of Scabiosa species in secondary metabolites such as iridoids, flavonoids and pentacyclic triterpenoids may contribute to its use in folk medicine. Details on the most recent and relevant pharmacological in vivo studies on the bioactive secondary metabolites isolated from Scabiosa species will be summarized and thoroughly discussed.