Antibacterial effects and action modes of asiatic acid

Mechanism of antibacterial phytoconstituents: an updated review

The increase of multiple drug resistance bacteria significantly diminishes the effectiveness of antibiotic armory and subsequently exaggerates the level of therapeutic failure. Phytoconstituents are exceptional substitutes for resistance-modifying vehicles. The plants appear to be a deep well for the discovery of novel antibacterial compounds. This is owing to the numerous enticing characteristics of plants, they are easily accessible and inexpensive, extracts or chemicals derived from plants typically have significant levels of action against infections, and they rarely cause serious adverse effects. The enormous selection of phytochemicals offers very distinct chemical structures that may provide both novel mechanisms of antimicrobial activity and deliver us with different targets in the interior of the bacterial cell. They can directly affect bacteria or act together with the crucial events of pathogenicity, in this manner decreasing the aptitude of bacteria to create resistance. Abundant phytoconstituents demonstrate various mechanisms of action toward multi drug resistance bacteria. Overall, this comprehensive review will provide insights into the potential of phytoconstituents as alternative treatments for bacterial infections, particularly those caused by multi drug resistance strains. By examining the current state of research in this area, the review will shed light on potential future directions for the development of new antimicrobial therapies.

Development of solid lipid microparticles (SLMs) containing asiatic acid for topical treatment of acne: Characterization, stability, in vitro and in vivo anti-acne assessment

Solid lipid microparticles (SLMs) represent a promising approach for drug delivery in anti-acne applications. In this study, asiatic acid-loaded SLMs (AASLMs) were prepared by melt emulsification method in conjunction with freeze-drying. Comprehensive evaluations comprised particle size, %entrapment efficiency (%EE), %labeled amount (%LA), surface morphology, stability, %release, %skin permeation, and anti-acne activity. The AASLMs exhibited an average particle size ranging from 7.46 to 38.86 µm, with %EE and %LA falling within the range of 31.56 to 100.00 and 90.43 to 95.38, respectively. The AASLMs demonstrated a spherical shape under scanning electron microscopy, and maintained stability over a 3-month period. Notably, formulations with 10 % and 15 % cetyl alcohol stabilized with poloxamer-188 (specifically F6 and F12) displayed a minimum inhibitory concentration (MIC) value of 75 mg/ml against Cutibacterium acnes. Furthermore, F12 exhibited a higher %release and %skin permeation compared to F6 over 24 h. In a single-blind clinical trial involving fifteen participants with mild-to-moderate acne, F12 showcased its potential not only in reducing porphyrin intensity and enhancing skin barriers but also in significantly improving skin hydration and brightness. However, further investigations with larger subject cohorts encompassing diverse age groups and genders are necessary to thoroughly establish the performance of the developed AASLMs.

Antibacterial Activity and Mechanism of Madecassic Acid against Staphylococcus aureus

Antibacterial resistance has become one of the most serious problems threating global health. To overcome this urgent problem, many scientists have paid great attention to developing new antibacterial drugs from natural products. Hence, for exploring new antibacterial drugs from Chinese medicine, a series of experiments were carried out for verifying and elucidating the antibacterial activity and mechanisms of madecassic acid (MA), which is an active triterpenoid compound isolated from the traditional Chinese medicine, Centella asiatica. The antibacterial activity was investigated through measuring the diameter of the inhibition zone, the minimum inhibitory concentration (MIC), the growth curve, and the effect on the bacterial biofilm, respectively. Meanwhile, the antibacterial mechanism was also discussed from the aspects of cell wall integrity variation, cell membrane permeability, and the activities of related enzymes in the respiratory metabolic pathway before and after the intervention by MA. The results showed that MA had an inhibitory effect on eight kinds of pathogenic bacteria, and the MIC values for Staphylococcus aureus, Methicillin-resistant Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Bacillus megaterium were 31.25, 62.5, 250, 125, 62.5, and 62.5 µg/mL, respectively. For instance, 31.25 µg/mL MA could inhibit the growth of Staphylococcus aureus within 28 h. The antibacterial mechanism experiments confirmed that MA could destroy the integrity of the cell membrane and cell wall of Staphylococcus aureus, causing the leakage of macromolecular substances, inhibiting the synthesis of soluble proteins, reducing the activities of succinate dehydrogenase and malate dehydrogenase, and interacting with DNA, leading to the relaxation and ring opening of supercoiled DNA. Besides, the activities of DNA topoisomerase I and II were both inhibited by MA, which led to the cell growth of Staphylococcus aureus being repressed. This study provides a theoretical basis and reference for the application of MA in the control and inhibition of food-borne Staphylococcus aureus.

Centella asiatica and Its Metabolite Asiatic Acid: Wound Healing Effects and Therapeutic Potential

An intense effort has been focused on new therapeutic approaches and the development of technologies for more efficient and rapid wound healing. The research for plants used for long time in traditional medicine in the treatment of wound has become a promising strategy to obtain drugs therapeutically useful in the acute and chronic wound management. In this context, Centella asiatica (Apiaceae) has been used to treat a variety of skin diseases, such as leprosy, lupus, varicose ulcers, eczema and psoriasis, in Asiatic traditional medicine for thousands of years. Studies have shown that Centella asiatica extracts (CAE) display activity in tissue regeneration, cell migration and wound repair process by promoting fibroblast proliferation and collagen synthesis. Preliminary findings have shown that the asiatic acid is one of the main active constituents of C. asiatica, directly associated with its healing activity. Thus, this study discusses aspects of the effects of Centella asiatica and its active component, asiatic acid, in different stages of the healing process of cutaneous wounds, including phytochemical and antimicrobial aspects that contribute to its therapeutic potential.

Effects of Temoporfin-Based Photodynamic Therapy on the In Vitro Antibacterial Activity and Biocompatibility of Gelatin-Hyaluronic Acid Cross-Linked Hydrogel Membranes

This study was performed to design a hydrogel membrane that exhibits antibacterial properties and guides different tissues. Gelatin and hyaluronic acid were used as the main structures, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) was used as a cross-linker, and temoporfin was used as an antibacterial agent. The results revealed that the hydrogel membrane impregnated with temoporfin (HM-T) had a fixation index of >89%. Temoporfin was used in conjunction with a diode laser and did not significantly affect EDC-induced cross-linking. The inhibitory activity of temoporfin showed that HM-T15 and HM-T30 (light exposure for 15 and 30 min, respectively) had remarkable antibacterial properties. The cell survival rate of HM-T15 was 73% of that of the control group, indicating that temoporfin exposure for 15 min did not exert cytotoxic effects on L-929 cells. HM and HM-T15 hydrogel membranes showed good cell adhesion and proliferation after 14 days of dark incubation. However, the hydrogel membrane containing temoporfin significantly reduced pro-inflammatory gene expression. In summary, the HM-T15 group showed potential as a biodegradable material for biocompatible tissue-guarded regeneration membranes with antibacterial properties. This study demonstrated the potential of temoporfin for innovative biomaterials and delivery systems applied to new regenerative periodontal therapies.

Synergistic Effect of Combination of a Temoporfin-Based Photodynamic Therapy with Potassium Iodide or Antibacterial Agents on Oral Disease Pathogens In Vitro

5, 10, 15, 20-Tetrakis(3-hydroxyphenyl)chlorin (temoporfin) is a photosensitizer used in photodynamic therapy for oral cancer and periodontal disease treatment. This study determined the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of temoporfin. Additionally, the combination of potassium iodide (KI) or antimicrobial agents in oral pathogens under hypoxic or normoxic conditions were determined. We also evaluated the biofilm removal effect and detected the expressions of the antibiotic resistance-related genes and biofilm formation-related genes of methicillin-resistant staphylococcus aureus (MRSA). The results provided reveal that the combination of the temoporfin and KI had a synergistic effect of reducing the MICs and MBCs of Lactobacillus acidophilus and Lactobacillus paracasei under normoxic and hypoxic conditions due to increasing H₂O₂ production. Temoporfin increased the biofilm removal of Aggregatibacter actinomycetemcomitans, Enterococcus faecalis, and Staphylococcus aureus under normoxic condition, and it reduced the antibiotic resistance-related genes expression of MRSA. The combination of temoporfin with ampicillin or chlorhexidine significantly enhanced the bactericidal effect on MRSA. This study provides a potential application of temoporfin on the clinical side against oral pathogens and the prevention of oral diseases.

In Vitro Antimicrobial Potential of CAPE and Caffeamide Derivatives against Oral Microbes

Caffeic acid phenethyl ester (CAPE) is a natural component isolated from propolis and used in traditional medicine. We aimed to investigate the antimicrobial properties and action mechanism of CAPE and caffeamide derivatives (26G and 36M) against oral disease microbes. We resolved the minimum inhibitory and bactericidal concentrations of 26G and 36M and their stability at different temperatures and pH. We also evaluated their effect on biofilm formation and antibiotic resistance gene expression in methicillin-resistant Staphylococcus aureus (MRSA). Our results revealed that 26G and 36M showed the best anticancer and antimicrobial activities, respectively, compared with the other four caffeamide derivatives. Both 26G and 36M showed heat-dependent decreases in antimicrobial activity. The 36M derivative was stable irrespective of pH, whereas 26G was not stable under high pH conditions. Biofilm formation and antibiotic resistance-related gene expression were consistent with their respective phenotypes. This study provides evidence for the potential application of CAPE and caffeamide derivatives in dental medicine to cure or prevent oral diseases.

Preparation, Antibacterial Potential, and Antibacterial Components of Fermented Compound Chinese Medicine Feed Additives

This experiment was conducted to compare the antibacterial ability and to identify the antibacterial components of different fermented compound Chinese medicine feed additives in order to develop one fermented compound Chinese medicine feed additive product that can effectively alleviate metritis, vaginitis, and mastitis of sows. The Oxford cup method and double dilution method were used to compare the antibacterial ability of three fermented compound Chinese medicine feed additives (A, B, and C). UHPLC-QE-MS-based untargeted metabolomics was used to identify the antibacterial components of fermented compound Chinese medicine feed additives. Results showed that among fermented compound Chinese medicine feed additives A, B, and C, additive A had the strongest ability to inhibit the growth of Staphylococcus aureus, Salmonella cholerae suis, Escherichia coli, and Streptococcus agalactiae. The MIC and MBC of additive A were the lowest for Staphylococcus aureus compared to that for the other three pathogens. The concentrations of 23 Chinese medicine ingredients (ellagic acid, guanine, camphor, L-valine, sinapine, dipropylphthalate, 3-hydroxy-5-isopropylidene-3,8-dimethyl-2,3,3a,4,5,8a-hexahydro-6(1H)-azulenone, 7-dihydroxy-2-(4-hydroxyphenyl)-8-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]-6-(3,4,5-trihydroxyoxan-2-yl)chromen-4-one, acetylcholine, farrerol, pyrogallol, ethyl gallate, demethylwedelolactone, methyl gallate, kaempferide, gallic acid, eriodictyol, threonic acid, inositol, 3′,4′,7-trihydroxyflavanone, taxifolin, asiatic acid, and isorhamnetin) in additive A were significantly (p < 0.05 or p < 0.01) higher than those in additive B, respectively. It is concluded that the mixture composed of 23 active components in fermented compound Chinese medicine feed additive A plays an important role in inhibiting the growth of Staphylococcus aureus, Salmonella cholerae suis, Escherichia coli, and Streptococcus agalactiae.

Anti-Planktonic and Anti-Biofilm Properties of Pentacyclic Triterpenes-Asiatic Acid and Ursolic Acid as Promising Antibacterial Future Pharmaceuticals

Due to the ever-increasing number of multidrug-resistant bacteria, research concerning plant-derived compounds with antimicrobial mechanisms of action has been conducted. Pentacyclic triterpenes, which have a broad spectrum of medicinal properties, are one of such groups. Asiatic acid (AA) and ursolic acid (UA), which belong to this group, exhibit diverse biological activities that include antioxidant, anti-inflammatory, diuretic, and immunostimulatory. Some of these articles usually contain only a short section describing the antibacterial effects of AA or UA. Therefore, our review article aims to provide the reader with a broader understanding of the activity of these acids against pathogenic bacteria. The bacteria in the human body can live in the planktonic form and create a biofilm structure. Therefore, we found it valuable to present the action of AA and UA on both planktonic and biofilm cultures. The article also presents mechanisms of the biological activity of these substances against microorganisms.

Are Uropathogenic Bacteria Living in Multispecies Biofilm Susceptible to Active Plant Ingredient-Asiatic Acid?

Urinary tract infections (UTIs) are a serious health problem in the human population due to their chronic and recurrent nature. Bacteria causing UTIs form multispecies biofilms being resistant to the activity of the conventionally used antibiotics. Therefore, compounds of plant origin are currently being searched for, which could constitute an alternative strategy to antibiotic therapy. Our study aimed to determine the activity of asiatic acid (AA) against biofilms formed by uropathogenic Escherichia coli, Enterobacter cloacae, and Pseudomonas aeruginosa. The influence of AA on the survival, biofilm mass formation by bacteria living in mono-, dual-, and triple-species consortia as well as the metabolic activity and bacterial cell morphology were determined. The spectrophotometric methods were used for biofilm mass synthesis and metabolic activity determination. The survival of bacteria was established using the serial dilution assay. The decrease in survival and a weakening of the ability to create biofilms, both single and multi-species, as well as changes in the morphology of bacterial cells were noticed. As AA works best against young biofilms, the use of AA-containing formulations, especially during the initial stages of infection, seems to be reasonable. However, there is a need for further research concerning AA especially regarding its antibacterial mechanisms of action.

In Vivo Biocompatible Self-Assembled Nanogel Based on Hyaluronic Acid for Aqueous Solubility and Stability Enhancement of Asiatic Acid

Asiatic acid (AA), a natural triterpene found in Centalla asiatica, possesses polypharmacological properties that can contribute to the treatment and prophylaxis of various diseases. However, its hydrophobic nature and rapid metabolic rate lead to poor bioavailability. The aim of this research was to develop a thermoresponsive nanogel from hyaluronic acid (HA) for solubility and stability enhancement of AA. Poly(N-isopropylacrylamide) (pNIPAM) was conjugated onto HA using a carbodiimide reaction followed by ¹H NMR characterization. pNIPAM-grafted HA (HA-pNIPAM) nanogels were prepared with three concentrations of polymer, 0.1, 0.15 and 0.25% w/v, in water by the sonication method. AA was loaded into the nanogel by the incubation method. Size, morphology, AA loading capacity and encapsulation efficiency (EE) were analyzed. In vitro cytocompatibility was evaluated in fibroblast L-929 cells using the PrestoBlue assay. Single-dose toxicity was studied using rats. HA-pNIPAM nanogels at a 4.88% grafting degree showed reversible thermo-responsive behavior. All nanogel formulations could significantly increase AA water solubility and the stability was higher in nanogels prepared with high polymer concentrations over 180 days. The cell culture study showed that 12.5 µM AA in nanogel formulations was considered non-toxic to the L-929 cells; however, a dose-dependent cytotoxic effect was observed at higher AA-loaded concentrations. In vivo study proved the non-toxic effect of AA loaded in HA-pNIPAM nanogels compared with the control. Taken together, HA-pNIPAM nanogel is a promising biocompatible delivery system both in vitro and in vivo for hydrophobic AA molecules.

Anti-Cancer Effects of Asiatic Acid, a Triterpene from Centilla asiatica L: A Review

BACKGROUND

Centilla asiatica L is a medicinal herb that has been widely used in folk medicine to treat various diseases. Asiatic Acid (AA), a triterpene and a known component of this herb, has been shown to display important biological activities, including anti-inflammatory, antibacterial, antidiabetic and antihyperlipidemic, neuroprotective, anxiolytic and antidepressant, hepatoprotective, pancreas protective, and cardio- protective.

OBJECTIVE

This review focuses on AA's anti-cancer effects on the basis of published literature found in a number of databases such as PubMed and Science Direct. Emphasis has been given to the mechanisms of action of its anti-cancer effect.

METHODS

A literature survey was conducted using known databases such as PubMed and Science Direct using the keywords 'Asiatic acid', pairing with 'cancer', 'tumor', 'anti-cancer effect', 'cytotoxic effect', 'anti-tumor activity', 'cell line', 'animal cancer', and 'human cancer'.

RESULTS

Findings suggest that AA exerts anti-cancer effects in several test systems through various pathways, including oxidative/antioxidant, anti-inflammatory, cytotoxicity, apoptotic cell death, necrosis, anti-angiogenesis, inhibition of proliferation and cell migration, and chemoprevention.

CONCLUSION

AA may be an effective plant-based cancer chemotherapeutic agent and a promising lead for the development of potent anticancer drugs.

Asiatic Acid, a Natural Compound that Exerts Beneficial Effects on the Cystometric and Biochemical Parameters in the Retinyl Acetate-Induced Model of Detrusor Overactivity

Scientists have been constantly looking for new synthetic and natural compounds that could have beneficial effects in bladder overactivity. Our attention was drawn by asiatic acid that influences a number of molecules and signaling pathways relevant for the proper functioning of the urinary tracts in humans. In the present project we wanted to check whether asiatic acid would have positive effects in the confirmed animal model of detrusor overactivity (DO) and whether it would affect the bladder blood flow, urothelium thickness, inflammatory and oxidative stress markers, neurotrophic and growth factors, and other parameters important for the activity of the urinary bladder. The outcomes of our study showed that a 14-day administration of asiatic acid (30 mg/kg/day) by oral gavage normalizes the cystometric parameters corresponding to DO and reduces the accompanying oxidative stress (measured by the levels of malondialdehyde–61,344 ± 24,908 pg/ml vs. 33,668 ± 5,071 pg/ml, 3-nitrotyrosine–64,615 ± 25,433 pg/ml vs. 6,563 ± 1,736 pg/ml, and NOS2–2,506 ± 411.7 vs. 3,824 ± 470.1 pg/ml). Moreover, it decreases the urinary secretion of neurotrophins (BDNF–304.4 ± 33.21 pg/ml vs. 119.3 ± 11.49 pg/ml and NGF–205.5 ± 18.50 vs. 109.7 ± 15.94 pg/ml) and prevents the changes in a range of biomarkers indicating the dysfunction of the urinary bladder, CGRP (421.1 ± 56.64 vs. 108.1 ± 11.73 pg/ml), E-Cadherin (773.5 ± 177.5 pg/ml vs. 1,560 ± 154.5 pg/ml), OCT3 (3,943 ± 814.6 vs. 1,018 ± 97.07 pg/ml), SNAP-23 (6,763 ± 808.9 pg/ml vs. 3,455 ± 554.5 pg/ml), SNAP-25 (2,038 ± 162.7 pg/ml vs. 833.3 ± 65.48), substance P (171.7 ± 16.86 pg/ml vs. 65.07 ± 8.250 pg/ml), SV2A (1,927 ± 175.3 pg/ml vs. 1,154 ± 254.9 pg/ml), tight junction protein 1 (360.1 ± 95.05 pg/ml vs. 563.4 ± 65.43 pg/ml), VAChT (16,470 ± 2,419 pg/ml vs. 7,072 ± 1,339 pg/ml), VEGFA (318.3 ± 37.89 pg/ml vs. 201.5 ± 22.91 pg/ml). The mentioned parameters are associated with smooth muscle contractions, urothelial barrier, transportation and release of transmitters, or bladder compensation. Thus, the presented findings allow to suggest a possible future role of asiatic acid in the prevention of conditions accompanied by DO, such as overactive bladder.

An aligned porous electrospun fibrous scaffold with embedded asiatic acid for accelerating diabetic wound healing

The diabetic non-healing wound is one of the most common complications of diabetics. The long-term stimulus of oxidative stress, inflammation and infection caused by the hyperglycemic microenvironment in the wound site always leads to a delayed healing process of the diabetic wound. To address this issue, in this study, we prepared an asiatic acid (AA)-embedded aligned porous poly(l-lactic acid) (PLLA) electrospun fibrous scaffold (AA-PL) for accelerating diabetic wound healing. The results showed that the electrospun fibers with nanopores on the surfaces were aligned in a single direction, while the AA was well embedded in the fibers and can be continuously released from them. The in vitro results revealed that the AA-PL scaffolds can effectively alleviate the H2O2-induced oxidative stress damage to HaCat cells and downregulate the LPS-induced pro-inflammatory cytokine (IL-1β, TNF-α, IL6) gene expression in RAW 264.7 macrophage cells. Moreover, the growth of E. coli and S. aureus could be inhibited by the AA-PL scaffolds. The in vivo study further demonstrated that the AA-PL scaffolds can accelerate the re-epithelization, angiogenesis and extracellular matrix formation of a wound by relieving the high oxidative stress, inflammation and infection in the diabetic wound site. This study suggests that the combination of hierarchical structures (nanopores on the aligned fibers) with the controllable release of AA from the scaffolds is an efficient and innovative strategy for the treatment of diabetic non-healing wounds.

Antiurolithiatic effects of pentacyclic triterpenes: The distance traveled from therapeutic aspects

Globally, approximately 12% of the population is inflicted by various types of urolithiasis. Standard treatments are available both to avert and treat urolithiasis, but with significant adverse side effects. Pentacyclic triterpenes represent a group of naturally occurring compounds which holds immense potential as therapeutic for treating kidney stone. This review aims to provide an integrative description on how pentacyclic triterpenes can effectively treat calcium oxalate urolithiasis through various mechanisms such as antioxidant, anti-inflammatory, diuretic, and angiotensin-converting enzyme inhibition. Some of the pentacylic triterpenes which shows promising activities include lupeol, oleanolic acid, betulin, and taraxasterol. Moreover, future perspectives in the development of pentacyclic triterpenes in formulations/drugs for urinary stone prevention are highlighted. It is anticipated that compiled information would serve as a scientific baseline to advocate further investigations on the potential of pentacyclic triterpenes in urolithiasis remediation.

Antimicrobial Effect of Asiatic Acid Against Clostridium difficile Is Associated With Disruption of Membrane Permeability

Antibiotic resistance is a major concern in Clostridium difficile, the causative agent of antibiotic-associated diarrhea. Reduced susceptibility to first- and second-line agents is widespread, therefore various attempts have been made to seek alternative preventive and therapeutic strategies against this pathogen. In this work, the antimicrobial properties of asiatic acid were evaluated against C. difficile. Asiatic acid displayed substantial inhibitory effects on 19 C. difficile isolates collected from different sources with minimal inhibitory concentrations ranging from 10 to 20 μg/ml. Time kill analysis and minimal bactericidal concentration revealed potential bactericidal activity of this compound. Asiatic acid induced membrane damages and alterations in morphological ultrastructure in C. difficile, thereby causing the leakage of intracellular substances. Moreover, asiatic acid also displayed an inhibitory effect on cell motility, but did not interfere with biofilm formation and spore germination. Analysis of drug combination showed no synergistic effect between asiatic acid and vancomycin/metronidazole. Altogether, asiatic acid exhibited strong antimicrobial activity against vegetative cells and could serve as an alternative resource for tackling C. difficile.

Pharmacological Properties, Molecular Mechanisms, and Pharmaceutical Development of Asiatic Acid: A Pentacyclic Triterpenoid of Therapeutic Promise

Asiatic acid (AA) is a naturally occurring aglycone of ursane type pentacyclic triterpenoids. It is abundantly present in many edible and medicinal plants including Centella asiatica that is a reputed herb in many traditional medicine formulations for wound healing and neuropsychiatric diseases. AA possesses numerous pharmacological activities such as antioxidant and anti-inflammatory and regulates apoptosis that attributes its therapeutic effects in numerous diseases. AA showed potent antihypertensive, nootropic, neuroprotective, cardioprotective, antimicrobial, and antitumor activities in preclinical studies. In various in vitro and in vivo studies, AA found to affect many enzymes, receptors, growth factors, transcription factors, apoptotic proteins, and cell signaling cascades. This review aims to represent the available reports on therapeutic potential and the underlying pharmacological and molecular mechanisms of AA. The review also also discusses the challenges and prospects on the pharmaceutical development of AA such as pharmacokinetics, physicochemical properties, analysis and structural modifications, and drug delivery. AA showed favorable pharmacokinetics and found bioavailable following oral or interaperitoneal administration. The studies demonstrate the polypharmacological properties, therapeutic potential and molecular mechanisms of AA in numerous diseases. Taken together the evidences from available studies, AA appears one of the important multitargeted polypharmacological agents of natural origin for further pharmaceutical development and clinical application. Provided the favorable pharmacokinetics, safety, and efficacy, AA can be a promising agent or adjuvant along with currently used modern medicines with a pharmacological basis of its use in therapeutics.

Investigation of biological activities of the flowers of Lagerstroemia speciosa, the Jarul flower of Bangladesh

BACKGROUND

Lagerstroemia speciosa (L.) Pers. (Family: Lythraceae) is used in traditional medicine in the treatment of diarrhea, diabetes and other diseases. The study was performed to conduct antioxidant, cytotoxic, thrombolytic, membrane stabilizing, antimicrobial, peripheral and central analgesic and hypoglycemic activity assays and phenobarbitone sodium-induced sleeping time test using crude methanol extract of flowers of L. speciosa and its different partitionates.

METHOD

The antioxidant potential was evaluated by determining the ability of the samples to scavenge 1, 1-diphenyl-2-picrylhydrazyl (DPPH) free radical. The cytotoxic potential was examined following the procedures of brine shrimp lethality bioassay. Thrombolytic potential was assayed using streptokinase as standard. The samples were subjected to membrane stabilizing activity assay under heat induced condition. Antimicrobial potential was observed by disc diffusion method. The ability of the extract to inhibit writhing induced by acetic acid was determined in peripheral analgesic activity assay. The extract was also tested for central analgesic and hypoglycemic activities by tail flicking and tail tipping methods in Swiss albino mice model, respectively. CNS depressant activity was evaluated by an assay in which sleep was induced in mice using phenobarbitone sodium.

RESULTS

The chloroform soluble fraction of L. speciosa extract demonstrated the highest antioxidant activity (IC50 = 4.20 ± 0.41 μg/ml) while the most prominent cytotoxic potency was showed by hexane soluble fraction (LC50 = 2.00 ± 0.31 μg/ml). Among the test samples, the carbon tetrachloride soluble fraction induced clot lysis (64.80 ± 0.27%) and prevented heat induced haemolysis (41.90 ± 0.10%) to the maximum extent. The largest zone of inhibition (19.0 mm) against Staphylococcus aureus, was also observed for the same fraction. In peripheral analgesic activity assay, 16.68% inhibition of writhing was documented for the L. speciosa extract (400 mg/kg body weight dose). The extract (400 mg/kg dose) also reduced blood sugar level by 56.12% after three hours of administration of glucose solution. In CNS depressant activity assay, mice of the sample group slept for shorter period of time compared to control group.

CONCLUSIONS

From our investigation, it can be suggested that, the extract should be further studied for possible phytochemicals responsible for the observed biological activities.

Pharmacological Review on Asiatic Acid and Its Derivatives: A Potential Compound

Natural triterpenes represent a group of pharmacologically active and structurally diverse organic compounds. The focus on these phytochemicals has been enormous in the past few years, worldwide. Asiatic acid (AA), a naturally occurring pentacyclic triterpenoid, is found mainly in the traditional medicinal herb Centella asiatica. Triterpenoid saponins, which are the primary constituents of C. asiatica, are commonly believed to be responsible for their extensive therapeutic actions. Published research work has described the molecular mechanisms underlying the various biological activities of AA and its derivatives, which vary for each chronic disease. However, a compilation of the various pharmacological properties of AA has not yet been done. Herein, we describe in detail the pharmacological properties of AA and its derivatives that inhibit multiple pathways of intracellular signaling molecules and transcription factors that are involved in the various stages of chronic diseases. Furthermore, the pharmacological activities of AA were compared with two natural compounds: curcumin and resveratrol. This review summarizes the research on AA and its derivatives and helps to provide future directions in the area of drug development.

Eudesmin attenuates Helicobacter pylori-induced epithelial autophagy and apoptosis and leads to eradication of H. pylori infection

Eudesmin has been proven to possess anti-inflammatory effects. In the present study, the effects of eudesmin on Helicobacter pylori (H. pylori)-mediated autophagy, apoptosis, immune response and inflammation were determined in human gastric adenocarcinoma (AGS) cells in vitro and in C57BL/6 mice in vivo. Detection of the production of interleukin (IL)-8, IL-1β and immunoglobulin M (IgM) was performed using ELISA. Identification of the activation of apoptosis-associated caspase-3, -8 and -9 proteins, Bcl-2-associated X protein (Bax) and BH3 interacting domain death agonist (Bid) protein, was determined through western blot analysis. Autophagy microtubule-associated protein 1A/1B-light chain 3, isoform B (LC-3B) expression was measured using immunostaining. The results of the present study demonstrated that eudesmin inhibited the growth of H. pylori, with increased inhibition activity against antibiotic resistant strains compared with the reference strain. In addition, H. pylori-induced IL-8 secretion, LC-3B expression and apoptosis-associated protein (caspase-3, -8 and -9, Bax and Bid) activation in AGS cells was suppressed by eudesmin. Furthermore, eudesmin suppressed IL-1β and IgM production in H. pylori-infected C57BL/6 mice in vivo. In conclusion, eudesmin may be developed as a promising therapeutic agent to prevent and/or treat H. pylori-associated gastric inflammation.

Statin use correlates with reduced risk of chronic osteomyelitis: a nationwide case-control study in Taiwan

BACKGROUND/OBJECTIVE

Potential association between prior statin use and chronic osteomyelitis is examined.

METHODS

A nationwide case-control study was conducted based on data taken from the Taiwan National Health Insurance program. The case group includes 2338 subjects aged 20-84 years newly diagnosed for chronic osteomyelitis from 2000 to 2013; the control group included 2338 randomly selected subjects without chronic osteomyelitis matched for sex, age, and index year. Statin use was respectively defined as "current", "recent" or "past" if the most recent statin prescription was filled <3 months, 3-6 months or ≥6 months prior to the chronic osteomyelitis diagnosis. Relative risk of chronic osteomyelitis associated with statin use was measured by the odds ratio (OR) with 95% confidence interval (CI) using the conditional logistic regression model.

RESULTS

After controlling for potential confounders, the adjusted ORs of chronic osteomyelitis were 0.57 for subjects with current statin use (95% CI 0.45, 0.72), 0.80 for subjects with recent statin use (95% CI 0.48, 1.33), and 1.00 for subjects with past statin use (95% CI 0.83, 1.20), compared patients with no prior statin use. In further analysis, the adjusted ORs of chronic osteomyelitis were 0.70 for subjects with cumulative statin use <12 months (95% CI 0.47, 1.07), and 0.56 for subjects with cumulative statins use ≥12 months (95% CI 0.41, 0.77), compared with those with no prior statin use.

CONCLUSIONS

Current statin use is associated with reduced concurrent diagnosis of chronic osteomyelitis, particularly for a cumulative statin use ≥12 months.

Metformin Use Correlates with Reduced Risk of Gallstones in Diabetic Patients: A 12-Year Follow-up Study

Objective: Few studies are available on the association between gallstones and metformin use. The objective of the study was to determine whether metformin use is associated with gallstones.

Methods: A population-based retrospective cohort study was conducted using the database of the Taiwan National Health Insurance Program. Subjects of newly diagnosed diabetes mellitus were included from 2002 to 2013. The metformin-exposure group was defined as ≥29 cumulative defined daily dose (DDD) of metformin use. The un-exposure group was defined as <29 cumulative DDD of metformin use. The major endpoint was a new diagnosis of gallstones during the follow-up period. A multivariable Cox proportional hazards regression model was used to evaluate the hazard ratio (HR) and 95% confidence interval (CI) of gallstones associated with metformin use.

Results: After controlling for potential confounders, the adjusted HRs of gallstones were 1.11 (95%CI: 0.84–1.46) for subjects with metformin dosage of 29–180 cumulative DDD, and 0.57 (95%CI: 0.42–0.78) for subjects with metformin dosage >180 cumulative DDD, compared with the un-exposure group.

Conclusion: Long-term use of metformin is associated with reduced risk of gallstones.

Head and neck cancer associated with increased rate of pulmonary tuberculosis in a population-based cohort study

The objective of this study was to examine the incidence and hazard ratio (HR) of pulmonary tuberculosis in patients with head and neck cancer in Taiwan.This population-based retrospective cohort study was conducted to analyze the database of the Taiwan National Health Insurance Program. There were 2522 subjects aged 20 to 84 years with newly diagnosed head and neck cancer as the head and neck cancer group between 2000 and 2012, and 10,064 randomly selected sex- and age-matched subjects without any cancer as the noncancer group. The incidence of pulmonary tuberculosis at the end of 2013 was estimated in both groups. A multivariable Cox proportional hazards regression model was used to estimate the HR and 95% confidence interval (CI) for pulmonary tuberculosis being associated with head and neck cancer.The overall incidence of pulmonary tuberculosis was 2.86-fold greater in the head and neck cancer group than that in the noncancer group (4.70 vs 1.64 per 1000 person-years, 95% CI, 2.53-3.24). After adjusting for confounding factors, the adjusted HR of pulmonary tuberculosis became 2.90 for the head and neck cancer group (95% CI, 2.11-3.99), compared with the noncancer group. In addition, male (adjusted HR 2.27, 95% CI, 1.29-4.00) and age (increase for 1 year, adjusted HR 1.06, 95% CI, 1.05-1.08) were associated with pulmonary tuberculosis.Head and neck cancer is significantly associated with 2.90-fold increased hazard of pulmonary tuberculosis in Taiwan, compared with the general population.

Population-based cohort study examining the association between splenectomy and empyema in adults in Taiwan

OBJECTIVE

This study aimed to investigate the association between splenectomy and empyema in Taiwan.

METHODS

A population-based cohort study was conducted using the hospitalisation dataset of the Taiwan National Health Insurance Program. A total of 13 193 subjects aged 20-84 years who were newly diagnosed with splenectomy from 2000 to 2010 were enrolled in the splenectomy group and 52 464 randomly selected subjects without splenectomy were enrolled in the non-splenectomy group. Both groups were matched by sex, age, comorbidities and the index year of undergoing splenectomy. The incidence of empyema at the end of 2011 was calculated. A multivariable Cox proportional hazards regression model was used to estimate the HR with 95% CI of empyema associated with splenectomy and other comorbidities.

RESULTS

The overall incidence rate of empyema was 2.56-fold higher in the splenectomy group than in the non-splenectomy group (8.85 vs 3.46 per 1000 person-years). The Kaplan-Meier analysis revealed a higher cumulative incidence of empyema in the splenectomy group than in the non-splenectomy group (6.99% vs 3.37% at the end of follow-up). After adjusting for confounding variables, the adjusted HR of empyema was 2.89 for the splenectomy group compared with that for the non-splenectomy group. Further analysis revealed that HR of empyema was 4.52 for subjects with splenectomy alone.

CONCLUSION

The incidence rate ratio between the splenectomy and non-splenectomy groups reduced from 2.87 in the first 5 years of follow-up to 1.73 in the period following the 5 years. Future studies are required to confirm whether a longer follow-up period would further reduce this average ratio. For the splenectomy group, the overall HR of developing empyema was 2.89 after adjusting for age, sex and comorbidities, which was identified from previous literature. The risk of empyema following splenectomy remains high despite the absence of these comorbidities.

Asiatic acid inhibits pulmonary inflammation induced by cigarette smoke

Asiatic acid (AA) is one of the major components of Titrated extract of Centella asiatica (TECA), which has been reported to possess antioxidant and anti-inflammatory activities. The purpose of this study was to investigate the protective effect of AA on pulmonary inflammation induced by cigarette smoke (CS). AA significantly attenuated the infiltration of inflammatory cells in bronchoalveolar lavage fluid (BALF) of CS exposure mice. AA also decreased ROS production and NE activity, and inhibited the release of proinflammatory cytokines in BALF. AA reduced the recruitment of inflammatory cells and MCP-1 expression in lung tissue of CS exposure mice. AA also attenuated mucus overproduction, and decreased the activation of MAPKs and NF-kB in lung tissue. Furthermore, AA increased HO-1 expression and inhibited the reduced expression of SOD3 in lung tissue. These findings indicate that AA effectively inhibits pulmonary inflammatory response, which is an important process in the development of chronic obstructive pulmonary disease (COPD) via suppression of inflammatory mediators and induction of HO-1. Therefore, we suggest that AA has the potential to treat inflammatory disease such as COPD.

Iron depletion strategy for targeted cancer therapy: utilizing the dual roles of neutrophil gelatinase-associated lipocalin protein

Decreasing iron uptake and increasing iron efflux may result in cell death by oxidative inactivation of vital enzymes. Applying the dual function of neutrophil gelatinase-associated lipocalin (NGAL) could achieve the goal of iron depletion in the cancer cells. Tyr106, Lys125 or Lys134 was the key binding site for NGAL protein to sequester iron-chelating siderophores. In this study, we employed all bioactive peptides in peptide databank to dock with the siderophore-binding sites of NGAL protein by virtual screening. In addition, we performed molecular dynamics (MD) simulation to observe the molecular character and structural variation of ligand-protein interaction. Glu-Glu-Lys-Glu (EEKE), Glu-Glu-Asp-Cys-Lys (EEDCK), and Gly-Glu-Glu-Cys-Asp (GEECD) were selected preliminarily by rigorous scoring functions for further investigation. GEECD was excluded due to higher binding total energy than the others. Moreover, we also excluded EEKE due to larger influence to the stability of binding residues by the information of root mean square fluctuation (RMSF) and principal component analysis (PCA). Thus, we suggested that EEDCK was the potential bioactive peptide which had been proved to inhibit malignant cells for targeted cancer therapy. Graphical Abstract Perspective drug design of occupying the siderophore-binding sites of NGAL outside the cell temporarily by a potential short peptide until NGAL enters into the cell, and releasing the siderophore-binding sites inside the cell.