The Antioxidant and Antihyperglycemic Activities of Bottlebrush Plant (Callistemon lanceolatus) Stem Extracts

Comparative Study of Callistemon citrinus (Bottlebrush) and Punica granatum (Pomegranate) Extracts for Sustainable Synthesis of Silver Nanoparticles and Their Oral Antimicrobial Efficacy

A comparative study was applied to investigate the potential of Callistemon citrinus (bottlebrush) flower extract (BBE) and Punica granatum (pomegranate) peel extracts (PPE) for the sustainable synthesis of the silver nanoparticles, Ag-BBE and Ag-PPE, respectively. The synthesis process of Ag NPs using the selected extracts was applied under optimized conditions. Hence, the effect of the selected plant's type on the different characteristics of the synthesized green Ag NPs was investigated. The UV-Vis spectroscopy revealed the presence of the characteristic silver peaks at 419 and 433 nm of the Ag-BBE and Ag-PPE, respectively. The XRD spectra reported the fcc phase formation of Ag NPs. The TEM results highlighted the morphological features of the synthesized Ag NPs. with a size range of 20-70 nm, and with 10-30 nm for Ag-BBE and Ag-PPE, correspondingly. The Raman spectra revealed characteristic silver bands in the Ag-PPE and reflected some bands related to the natural extract in the Ag-BBE sample. The antimicrobial activity and statistical analysis investigation were conducted against four selected oral pathogens (Staphylococcus aureus (SA), Candida albicans (CA), Staphylococcus epidermidis (S. epi), and Enterococcus faecalis (EF)). Both tested extracts, BBE, and PPE, revealed potential effectivity as reducing and capping agents for Ag NP green synthesis. However, the synthesized NPs demonstrated different features, depending on the used extract, reflecting the influence of the plant's biomolecules on the nanoparticles' properties.

Antitubercular drugs: possible role of natural products acting as antituberculosis medication in overcoming drug resistance and drug-induced hepatotoxicity

Mycobacterium tuberculosis (Mtb) is a pathogenic bacterium which causes tuberculosis (TB). TB control programmes are facing threats from drug resistance. Multidrug-resistant (MDR) and extensively drug-resistant (XDR) Mtb strains need longer and more expensive treatment with many medications resulting in more adverse effects and decreased chances of treatment outcomes. The World Health Organization (WHO) has emphasised the development of not just new individual anti-TB drugs, but also novel medication regimens as an alternative treatment option for the drug-resistant Mtb strains. Many plants, as well as marine creatures (sponge; Haliclona sp.) and fungi, have been continuously used to treat TB in various traditional treatment systems around the world, providing an almost limitless supply of active components. Natural products, in addition to their anti-mycobacterial action, can be used as adjuvant therapy to increase the efficacy of conventional anti-mycobacterial medications, reduce their side effects, and reverse MDR Mtb strain due to Mycobacterium's genetic flexibility and environmental adaptation. Several natural compounds such as quercetin, ursolic acid, berberine, thymoquinone, curcumin, phloretin, and propolis have shown potential anti-mycobacterial efficacy and are still being explored in preclinical and clinical investigations for confirmation of their efficacy and safety as anti-TB medication. However, more high-level randomized clinical trials are desperately required. The current review provides an overview of drug-resistant TB along with the latest anti-TB medications, drug-induced hepatotoxicity and oxidative stress. Further, the role and mechanisms of action of first and second-line anti-TB drugs and new drugs have been highlighted. Finally, the role of natural compounds as anti-TB medication and hepatoprotectants have been described and their mechanisms discussed.

Use of Callistemon citrinus as a gastroprotective and anti-inflammatory agent on indomethacin-induced gastric ulcers in obese rats

Background

Obesity leads to an elevated risk of developing gastrointestinal disease such as gastric ulcers. Callistemon citrinus leaf extract has shown antioxidant, antimicrobial, hepatoprotective, and chemoprotective effects against colon cancer. The aim of this study is to evaluate the gastroprotective effect of C. citrinus leaf extract on indomethacin-induced gastric ulcers in obese rats.

Methods

Gastric ulcers were induced in female obese Wistar rats using a single oral dose of indomethacin (IND). In the first stage, the rats were fed with a high fat sugar diet (HFSD) for 15 weeks to induce obesity and, at the same time, the diet of the other group of animals included daily administration of ethanolic C. citrinus leaf extract (250 mg/kg) in addition to HFSD. In the second stage, gastric ulcers were induced with IND (30 mg/kg). The gastroprotective activity of C. citrinus, the inflammatory enzyme activities, and cytokines in the stomach were determined.

Results

C. citrinus produced a reduction of gastric lesions caused by IND. Myeloperoxidase (MPO), cyclooxygenase-2 (COX-2), and 5-lipoxygenase (5-LOX) activities also decreased. Although inflammatory biomarkers such as TNFα, IL-6, AOPP, and leptin were significantly decreased by C. citrinus, adiponectin levels increased. Moreover, C. citrinus decreased weight gain and morphological and biochemical parameters.

Conclusion

The use of indomethacin in rats fed with a high fat-sugar diet increased gastric ulcers. Gastroprotective effect of C. citrinus in obese rats is attributed to the reduction of pro-inflammatory cytokines and the inflammatory enzymes.

Mechanism and recent updates on insulin-related disorders

Insulin, a small protein with 51 amino acids synthesized by pancreatic β-cells, is crucial to sustain glucose homeostasis at biochemical and molecular levels. Numerous metabolic dysfunctions are related to insulin-mediated altered glucose homeostasis. One of the significant pathophysiological conditions linked to the insulin associated disorder is diabetes mellitus (DM) (type 1, type 2, and gestational). Insulin resistance (IR) is one of the major underlying causes of metabolic disorders despite its association with several physiological conditions. Metabolic syndrome (MS) is another pathophysiological condition that is associated with IR, hypertension, and obesity. Further, several other pathophysiological disorders/diseases are associated with the insulin malfunctioning, which include polycystic ovary syndrome, neuronal disorders, and cancer. Insulinomas are an uncommon type of pancreatic β-cell-derived neuroendocrine tumor that makes up 2% of all pancreatic neoplasms. Literature revealed that different biochemical events, molecular signaling pathways, microRNAs, and microbiota act as connecting links between insulin disorder and associated pathophysiology such as DM, insuloma, neurological disorder, MS, and cancer. In this review, we focus on the insulin-related disorders and the underlying mechanisms associated with the pathophysiology.

Anti-proliferative, apoptosis inducing, and antioxidant potential of Callistemon lanceolatus bark extracts: an in vitro and in silico study

The present study reports anticancer and antioxidant activities of Callistemon lanceolatus bark extracts. Anticancer activity was studied against MDA-MB-231 cells. Antioxidant assessment of the chloroform and methanol extracts showed considerable free radical scavenging, metal ion chelating, and reducing power potential. Chloroform extract exhibited potent inhibition of cancer cell proliferation in MTT assay (IC₅₀ 9.6 μg/ml) and promoted programmed cell death. Reactive oxygen species (ROS) generation, mitochondria membrane potential (MMP) disruption ability, and nuclear morphology changes were studied using H₂-DCFDA, JC-1, and Hoechst dyes, respectively, using confocal microscopy. Apoptotic cells exhibited fragmented nuclei, increased ROS generation, and altered MMP in dose- and time-dependent manner. Chloroform extract upregulated the BAX-1 and CASP3 mRNA expression coupled with downregulation of BCL-2 gene. Further, in silico docking of phytochemicals present in C. lanceolatus with anti-apoptotic Bcl-2 protein endorsed apoptosis by its inhibition and thus corroborated the experimental findings. Obatoclax, a known inhibitor of Bcl-2 was used as a reference compounds.

Modulatory effect of caffeic acid in alleviating diabetes and associated complications

Diabetes mellitus (DM) is one of the most common metabolic disorders characterized by elevated blood glucose levels. Prolonged uncontrolled hyperglycemia often leads to multi-organ damage including diabetic neuropathy, nephropathy, retinopathy, cardiovascular disorders, and diabetic foot ulcers. Excess production of free radicals causing oxidative stress in tissues is often considered to be the primary cause of onset and progression of DM and associated complications. Natural polyphenols can be used to induce or inhibit the expression of antioxidant enzymes such as glutathione peroxidase, heme oxygenase-1, superoxide dismutase, and catalase that are essential in maintaining redox balance, and ameliorate oxidative stress. Caffeic acid (CA) is a polyphenolderived from hydroxycinnamic acid and possesses numerous physiological properties includ-ing antioxidant, anti-inflammatory, anti-atherosclerotic, immune-stimulatory, cardioprotective, antiproliferative, and hepatoprotective activities. CA acts as a regulatory compound affecting numerous biochemical pathways and multiple targets. These include various transcription factors such as nuclear factor-B, tumor necrosis factor-α, interleukin-6, cyclooxygenase-2, and nuclear factor erythroid 2-related factor 2. Therefore, this review summarizes the pharmacological properties, molecular mechanisms, and pharmacokinetic profile of CA in mitigating the adverse effects of DM and associated complications. The bioavailability, drug delivery, and clinical trials of CA have also been discussed.

Current therapeutic modalities and chemopreventive role of natural products in liver cancer: Progress and promise

Liver cancer is a severe concern for public health officials since the clinical cases are increasing each year, with an estimated 5-year survival rate of 30%–35% after diagnosis. Hepatocellular carcinoma (HCC) constitutes a significant subtype of liver cancer (approximate75%) and is considered primary liver cancer. Treatment for liver cancer mainly depends on the stage of its progression, where surgery including, hepatectomy and liver transplantation, and ablation and radiotherapy are the prime choice. For advanced liver cancer, various drugs and immunotherapy are used as first-line treatment, whereas second-line treatment includes chemotherapeutic drugs from natural and synthetic origins. Sorafenib and lenvatinib are first-line therapies, while regorafenib and ramucirumab are second-line therapy. Various metabolic and signaling pathways such as Notch, JAK/ STAT, Hippo, TGF-β, and Wnt have played a critical role during HCC progression. Dysbiosis has also been implicated in liver cancer. Drug-induced toxicity is a key obstacle in the treatment of liver cancer, necessitating the development of effective and safe medications, with natural compounds such as resveratrol, curcumin, diallyl sulfide, and others emerging as promising anticancer agents. This review highlights the current status of liver cancer research, signaling pathways, therapeutic targets, current treatment strategies and the chemopreventive role of various natural products in managing liver cancer.

Chemical Constituents of Callistemon subulatus and Their Anti-Pancreatic Cancer Activity against Human PANC-1 Cell Line

An n-hexane extract of Callistemon subulatus was found to exhibit potent cytotoxicity against PANC-1 human pancreatic cancer cells, preferentially under nutrition starvation conditions, with a PC₅₀ value of 6.2 µg/mL. Phytochemical investigation of this bioactive extract resulted in the isolation of fifteen compounds (1–15), including a new compound, subulatone A (–). The structure of compound 1 was elucidated using HRFABMS and NMR spectroscopic analyses. The isolated compounds were tested for their preferential cytotoxicity against the PANC-1 human pancreatic cancer cell line, using an anti-austerity strategy. Among these, myrtucommulone A (2) showed highly potent preferential cytotoxicity, with a PC₅₀ value of 0.28 µM. Myrtucommulone A (2) was found to alter PANC-1 cell morphology, inhibit cell migration, and downregulate the PI3K/Akt/mTOR and autophagy signaling pathways in nutrient-deprived media, leading to cancer cell death. Therefore, myrtucommulone A (2) is a lead compound for anticancer drug development based on an anti-austerity strategy.

Pharmacological action and underlying molecular mechanism of Callistemon: A genus of promising medicinal herbs

INTRODUCTION

The genus Callistemon belongs to a group of medically significant plants which have found tremendous use in traditional medicine across the globe. They are reported for anti-cancer, neuroprotective, anti-inflammatory, antioxidant, anti-microbial, and many other significant medicinal attributes. However, the current use of this genus is limited mainly to ornamental and recreational purposes. Recent studies have reported several novel compounds like phloroglucinol derivatives, terpenes, phenolics, etc., from Callistemon spp., which have great medical significance. Further, there is a surge of recent studies reporting novel pharmacological properties of Callistemon. The number of review studies discussing the underlying molecular mechanism behind the pharmacological action of Callistemon is quite limited.

METHODS

The literature search for studies published from 1991 to 2021 using Google scholar and PubMed were selected. The review documented relevant literature focused on Callistemon spp exhibiting significant pharmacological effects.

RESULTS

This review deals with the pharmacological properties of Callistemon and the underlying molecular mechanism responsible for protective effect in several pathophysiological conditions. This study updated the current information regarding the medicinal importance of Callistemon spp. for research and the public community.

DISCUSSION AND CONCLUSIONS

The preliminary studies, interrogating pharmacological properties of Callistemon spp., hold great promise and demand further research to decipher the mode of action. More and more research are needed in this direction to explore the full potential of the genus Callistemon as a medicinal herb.

Evaluation of antidiabetic activity of dietary phenolic compound chlorogenic acid in streptozotocin induced diabetic rats: Molecular docking, molecular dynamics, in silico toxicity, in vitro and in vivo studies

BACKGROUND

Chlorogenic acid is amongst the well-known polyphenolic compounds being used in human food and beverages. Its presence has been reported in tea leaves, roasted green beans, coffee, cocoa, berry fruits, apples, citrus fruits, and pears.

OBJECTIVE

The present study aims to elucidate the effectiveness of chlorogenic acid on in silico and in vitro inhibition of glucose metabolising enzymes (α-amylase and α-glucosidase) and on blood-based markers associated with diabetic complications in vivo.

METHODS

Docking and molecular dynamics studies were performed using GLIDE (Schrodinger, LLC, NY, 2019-2) and Maestro-Desmond Interoperability Tools, version 4.1 (Schrödinger, NY, 2015), respectively. α-Amylase and α-glucosidase inhibitory activities of chlorogenic acid were measured in vitro. Diabetes was induced in adult Wistar rats by injecting streptozotocin (50 mg/kg). Biochemical assays were performed using standard kits.

RESULT

The in silico studies for α-amylase and α-glucosidase with chlorogenic acid suggested that the ligand was stable and strongly bound with the above-mentioned proteins. During in vitro studies, chlorogenic acid inhibited both the enzymes in a dose-dependent manner (5-30 μg/mL). In addition, chlorogenic acid treatment for 28 days significantly suppressed the increase in blood glucose, total cholesterol, triglyceride, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, γ-glutamyl transferase, alkaline phosphatase, total bilirubin, creatinine, urea, uric acid, and feed intake levels in diabetic rats. Chlorogenic acid also caused significant improvement in body weight, serum HDL-cholesterol, total protein, and albumin levels leading to betterment in atherogenic indices related to diabetes-associated cardiovascular risks.

CONCLUSION

The findings indicated that chlorogenic acid inhibited α-amylase and α-glucosidase and significantly decreased diabetes associated hyperglycemia, hyperlipidemia, and hepatorenal damage, making it a possible functional food ingredient and drug candidate for the management of diabetes and related complications.

Antioxidant, anti-inflammatory and hepatoprotective activities of Terminalia bellirica and its bioactive component ellagic acid against diclofenac induced oxidative stress and hepatotoxicity

Long term usage and overdose of diclofenac (DCF), an anti-inflammatory drug is known to cause oxidative stress and liver injury. The present study reports the antioxidant, anti-inflammatory and hepatoprotective activities of Terminalia bellirica (Tb) fruit aqueous and ethyl acetate extracts and its bioactive compound ellagic acid (EA) against DCF-induced toxicity. in vitro antioxidant activities were measured by ABTS and FRAP assays while anti‐inflammatory activity was assessed by the albumin denaturation method. The adverse effects of DCF and hepatoprotective potential of Tb extracts and EA were assessed in serum and liver tissue of rats after oral administration for 21 days. Silymarin was used as standard hepatoprptective agent for comparison. Hepatic markers analyzed in serum included ALP, GPT, GOT, LDH, γ-glutamyl transferase, total protein, creatinine, and uric acid while superoxide dismutase (SOD) and catalase (CAT) were analyzed in liver tissue. The EA exhibited superior ABTS radical scavenging, FRAP, and anti-inflammatory activities as compared to fruit extracts. DCF treatment led to rise in the levels of most of the serum hepatic markers with decline in total serum protein as well as SOD and CAT in liver tissue. The supplementation of extracts, EA and silymarin in DCF treated rats significantly reduced the adverse effects of DCF on serum and tissue markers. Histopathology of the liver indicated that extracts and EA significantly decreased the degree of liver fibrosis. The hepatoprotective ability of EA was comparable to the silymarin but activity of Tb fruit extracts was little lower. Among fruit extracts ethyl acetate extract exhibited better activity than aqueous extract. The results revealed that ellagic acid and T. bellirica fruit extracts have potential to mitigate oxidative stress and hepatotoxicity produced by long term use of diclofenac.

Aceclofenac-induced hepatotoxicity: An ameliorative effect of Terminalia bellirica fruit and ellagic acid

BACKGROUND

Aceclofenac (ACF), a widely used nonsteroidal anti-inflammatory drug, has been associated with a number of severe cases of clinical hepatotoxicity. Terminalia bellirica, an evergreen tree, is known to have several ethnomedicinal uses including antioxidant and hepatoprotective effects. Hence T. bellirica fruit extracts and its phytoconstituent ellagic acid (EA) are expected to provide protection against oxidative stress and liver damage produced by long-term use of ACF.

AIM

To evaluate the antioxidant and hepatoprotective activities of T. bellirica fruit extracts and EA against ACF-induced toxicity in albino Wistar rats.

METHODS

The in vitro antioxidant activities of T. bellirica fruit ethyl acetate and aqueous extracts were measured by metal ion chelation and nitric oxide radical scavenging assays. The in vivo antioxidant and hepatoprotective effects of T. bellirica extracts (200 mg/kg) and EA (40 mg/kg) in ACF-induced hepatotoxic rats were assessed in serum and liver tissue after oral administration for 21 d. Silymarin (40 mg/kg) was used as a standard control. Oxidative stress markers in the blood (ferric reducing ability of plasma and lipid peroxidation inhibition) and liver tissues (superoxide dismutase, catalase and malondialdehyde) were analyzed using standard protocols. Liver function markers such as alkaline phosphatase, glutamic pyruvic transaminase, glutamic oxaloacetic transaminase, lactate dehydrogenase, γ-glutamyl transferase, creatinine, total protein, and uric acid were evaluated in rat serum.

RESULTS

The T. bellirica fruit ethyl acetate extract exhibited superior metal ion chelating and nitric oxide radical scavenging abilities during in vitro antioxidant assays as compared to aqueous extracts. Oral administration of ACF in rats (15 mg/kg) for 21 d produced oxidative stress and adversely affected liver function suggesting liver injury. Treatment with extracts (ethyl acetate and aqueous), EA and silymarin accounted for a significant reduction in the adverse effects of ACF on oxidative stress and liver function markers in serum and hepatic tissue in rats. Histopathological evaluation of the liver indicated that the extracts and EA significantly decreased the degree of liver damage. The in vivo efficacy of EA was higher than T. bellirica fruit extracts. Of these extracts, ethyl acetate extract revealed comparatively better antioxidant and hepatoprotective activity.

CONCLUSION

Ellagic acid and T. bellirica fruit extracts exhibited considerable hepatoprotective and antioxidant activities in long-term ACF-treated rats.

Terminalia bellirica (Gaertn.) roxb. (Bahera) in health and disease: A systematic and comprehensive review

BACKGROUND

Terminalia bellirica (Gaertn.) Roxb. is one of the oldest medicinal herbs of India, Pakistan, Nepal, Bangladesh and Sri Lanka as well as South-East Asia. Its medicinal utility has been described in the different traditional medicinal systems, such as Ayurveda, Unani, Siddha, and traditional Chinese medicine.

PURPOSE

The present study is aimed at providing a comprehensive overview on the traditional medicinal use, major phytoconstituents, biological and pharmacological activities and related mechanisms of actions and clinical studies of T. bellirica. Another objective is to describe current limitations and future direction of T. bellirica-related research.

METHODS

PubMed, ScienceDirect, Scopus, Cochrane Library, and EBOSCO host databases were selected to explore literature published between 1980 and 2020 (till March). Keywords used in various combinations comprised of Terminalia bellirica, phytoconstituents, health effects, pharmacological activities, molecular targets, in vitro, in vivo, clinical studies, and disease prevention.

RESULTS

A broad spectrum in vitro and in vivo studies suggested various biological and pharmacological effects, including antioxidant, anti-inflammatory, immunomodulatory, antimicrobial, hepatoprotective, renoprotective, antidiabetic, anti-hyperlipidemic, and anticancer activities. Diverse bioactivities of T. bellirica have been ascribed to the presence of many bioactive phytochemicals, such as glucoside, tannins, gallic acid, corilagin, ellagic acid, ethyl gallate, galloyl glucose, chebulagic acid, and arjunolic acid.

CONCLUSION

Preclinical and clinical studies have suggested that T. bellirica plant and its phytoconstituents have immense potential for prevention and treatment of various diseases. Additional in vivo studies and clinical trials are warranted to realize the complete medicinal attributes of this plant.