Preparation and evaluation of a niosomal delivery system containing G. mangostana extract and study of its anti-Acanthamoeba activity.

Garcinia mangostana extract (GME) has severe pharmacokinetic deficiencies and is made up of a variety of bioactive components. GME has proven its anti-Acanthamoeba effectiveness. In this investigation, a GME-loaded niosome was developed to increase its potential therapeutic efficacy. A GME-loaded niosome was prepared by encapsulation in a mixture of span60, cholesterol, and chloroform by the thin film hydration method. The vesicle size, zeta potential, percentage of entrapment efficiency, and stability of GME-loaded niosomes were investigated. The values for GME-loaded niosome size and zeta potential were 404.23 ± 4.59 and -32.03 ± 0.95, respectively. The delivery system enhanced the anti-Acanthamoeba activity, which possessed MIC values of 0.25-4 mg mL-1. In addition, the niosomal formulation decreased the toxicity of GME by 16 times. GME-loaded niosome must be stored at 4 °C, as the quantity of remaining GME encapsulated is greater at this temperature than at room temperature. SEM revealed the damage to the cell membrane caused by trophozoites and cysts, which led to dead cells. In light of the above, it was found that GME-loaded niosomes had better anti-Acanthamoeba activity. The study suggested that GME-loaded niosomes could be used as an alternative to Acanthamoeba's therapeutic effects.

Acinetobacter baumannii in suspected bacterial infections: Association between multidrug resistance, virulence genes, & biofilm production.

BACKGROUND OBJECTIVES: Acinetobacter baumannii has emerged as a nosocomial pathogen with a tendency of high antibiotic resistance and biofilm production. This study aimed to determine the occurrence of A. baumannii from different clinical specimens of suspected bacterial infections and furthermore to see the association of biofilm production with multidrug resistance and expression of virulence factor genes in A. baumannii. METHODS: A. baumannii was confirmed in clinical specimens by the detection of the blaOXA-51-like gene. Biofilm production was tested by microtitre plate assay and virulence genes were detected by real-time PCR. RESULTS: A. baumannii was isolated from a total of 307 clinical specimens. The isolate which showed the highest number of A. baumannii was an endotracheal tube specimen (44.95%), then sputum (19.54%), followed by pus (17.26%), urine (7.49%) and blood (5.86%), and <2 per cent from body fluids, catheter-tips and urogenital specimens. A resistance rate of 70-81.43 per cent against all antibiotics tested, except colistin and tigecycline, was noted, and 242 (78.82%) isolates were multidrug-resistant (MDR). Biofilm was detected in 205 (66.78%) with a distribution of 54.1 per cent weak, 10.42 per cent medium and 2.28 per cent strong biofilms. 71.07 per cent of MDR isolates produce biofilm (P<0.05). Amongst virulence factor genes, 281 (91.53%) outer membrane protein A (OmpA) and 98 (31.92%) biofilm-associated protein (Bap) were detected. Amongst 100 carbapenem-resistant A. baumannii, the blaOXA-23-like gene was predominant (96%), the blaOXA-58-like gene (6%) and none harboured the blaOXA-24-like gene. The metallo-ß-lactamase genes blaIMP-1 (4%) and blaVIM-1(8%) were detected, and 76 per cent showed the insertion sequence ISAba1. INTERPRETATION CONCLUSIONS: The majority of isolates studied were from lower respiratory tract specimens. The high MDR rate and its positive association with biofilm formation indicate the nosocomial distribution of A. baumannii. The biofilm formation and the presence of Bap were not interrelated, indicating that biofilm formation was not regulated by a single factor. The MDR rate and the presence of OmpA and Bap showed a positive association (P<0.05). The isolates co-harbouring different carbapenem resistance genes were the predominant biofilm producers, which will seriously limit the therapeutic options suggesting the need for strict antimicrobial stewardship and molecular surveillance in hospitals.

Green synthesis of silver nanoparticles using Ocimum sanctum Linn. and its antibacterial activity against multidrug resistant Acinetobacter baumannii.

The biosynthesis of nanoparticles using the green route is an effective strategy in nanotechnology that provides a cost-effective and environmentally friendly alternative to physical and chemical methods. This study aims to prepare an aqueous extract of Ocimum sanctum (O. sanctum)-based silver nanoparticles (AgNPs) through the green route and test their antibacterial activity. The biosynthesized silver nanoparticles were characterised by colour change, UV spectrometric analysis, FTIR, and particle shape and size morphology by SEM and TEM images. The nanoparticles are almost spherical to oval or rod-shaped with smooth surfaces and have a mean particle size in the range of 55 nm with a zeta potential of -2.7 mV. The antibacterial activities of AgNPs evaluated against clinically isolated multidrug-resistant Acinetobacter baumannii (A. baumannii) showed that the AgNPs from O. sanctum are effective in inhibiting A. baumannii growth with a zone of inhibition of 15 mm in the agar well diffusion method and MIC and MBC of 32 µg/mL and 64 µg/mL, respectively. The SEM images of A. baumannii treated with AgNPs revealed damage and rupture in bacterial cells. The time-killing assay by spectrophotometry revealed the time- and dose-dependent killing action of AgNPs against A. baumannii, and the assay at various concentrations and time intervals indicated a statistically significant result in comparison with the positive control colistin at 2 µg/mL (P < 0.05). The cytotoxicity test using the MTT assay protocol showed that prepared nanoparticles of O. sanctum are less toxic against human cell A549. This study opens up a ray of hope to explore the further research in this area and to improve the antimicrobial activities against multidrug resistant bacteria.

The Garlic Tree of Borneo, Scorodocarpus borneensis (Baill.) Becc. (Olacaceae): Potential Utilization in Pharmaceutical, Nutraceutical, and Functional Cosmetic Industries.

Scorodocarpus borneensis (Baill.) Becc. is attracting increased attention as a potential commercial medicinal plant product in Southeast Asia. This review summarizes the current knowledge on the taxonomy, habitat, distribution, medicinal uses, natural products, pharmacology, toxicology, and potential utilization of S. borneesis in the pharmaceutical/nutraceutical/functional cosmetic industries. All data in this review were compiled from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and a library search from 1866 to 2022. A total of 33 natural products have been identified, of which 11 were organosulfur compounds. The main organosulfur compound in the seeds is bis-(methylthiomethyl)disulfide, which inhibited the growth of a broad spectrum of bacteria and fungi, T-lymphoblastic leukemia cells, as well as platelet aggregation. Organic extracts evoked anti-microbial, cytotoxic, anti-free radical, and termiticidal effects. S. borneensis and its natural products have important and potentially patentable pharmacological properties. In particular, the seeds have the potential to be used as a source of food preservatives, antiseptics, or termiticides. However, there is a need to establish acute and chronic toxicity, to examine in vivo pharmacological effects and to perform clinical studies.

Synthesis, Crystal Structure, Antibacterial and In Vitro Anticancer Activity of Novel Macroacyclic Schiff Bases and Their Cu (II) Complexes Derived from S-Methyl and S-Benzyl Dithiocarbazate.

A series of novel macroacyclic Schiff base ligands and their Cu (II) complexes were synthesised via reacting dicarbonyls of varying chain lengths with S-methyl dithiocarbazate (SMDTC) and S-benzyl dithiocarbazate (SBDTC) followed by coordination with Cu (II) ions. X-ray crystal structures were obtained for compound 4, an SBDTC-diacetyl analogue, and Cu7, an SMDTC-hexanedione Cu (II) complex. Anticancer evaluation of the compounds showed that Cu1, an SMDTC-glyoxal complex, demonstrated the highest cytotoxic activity against MCF-7 and MDA-MB-231 breast cancer cells with IC50 values of 1.7 µM and 1.4 µM, respectively. There was no clear pattern observed between the effect of chain length and cytotoxic activity; however, SMDTC-derived analogues were more active than SBDTC-derived analogues against MDA-MB-231 cells. The antibacterial assay showed that K. rhizophila was the most susceptible bacteria to the compounds, followed by S. aureus. Compound 4 and the SMDTC-derived analogues 3, 5, Cu7 and Cu9 possessed the highest antibacterial activity. These active analogues were further assessed, whereby 3 possessed the highest antibacterial activity with an MIC of <24.4 µg/mL against K. rhizophila and S. aureus. Further antibacterial studies showed that at least compounds 4 and 5 were bactericidal. Thus, Cu1 and 3 were the most promising anticancer and antibacterial agents, respectively.

Antibacterial and Antifungal Terpenes from the Medicinal Angiosperms of Asia and the Pacific: Haystacks and Gold Needles.

This review identifies terpenes isolated from the medicinal Angiosperms of Asia and the Pacific with antibacterial and/or antifungal activities and analyses their distribution, molecular mass, solubility, and modes of action. All data in this review were compiled from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and library searches from 1968 to 2022. About 300 antibacterial and/or antifungal terpenes were identified during this period. Terpenes with a MIC ≤ 2 µg/mL are mostly amphiphilic and active against Gram-positive bacteria, with a molecular mass ranging from about 150 to 550 g/mol, and a polar surface area around 20 Ų. Carvacrol, celastrol, cuminol, dysoxyhainic acid I, ent-1ß,14ß-diacetoxy-7α-hydroxykaur-16-en-15-one, ergosterol-5,8-endoperoxide, geranylgeraniol, gossypol, 16α-hydroxy-cleroda-3,13 (14)Z-diene-15,16-olide, 7-hydroxycadalene, 17-hydroxyjolkinolide B, (20R)-3ß-hydroxy-24,25,26,27-tetranor-5α cycloartan-23,21-olide, mansonone F, (+)-6,6'-methoxygossypol, polygodial, pristimerin, terpinen-4-ol, and α-terpineol are chemical frameworks that could be candidates for the further development of lead antibacterial or antifungal drugs.

Development of SARS-CoV-2 Vaccine: Challenges and Prospects.

The WHO declared coronavirus disease 2019 (COVID-19) a pandemic in March 2020, which was caused by novel coronavirus severe acute respiratory coronavirus 2 (SARS-CoV-2). SARS-CoV-2 made its first entry into the world in November 2019, and the first case was detected in Wuhan, China. Mutations in the SARS-CoV-2 genome distressed life in almost every discipline by the extended production of novel viral variants. In this article, authorized SARS-CoV-2 vaccines including mRNA vaccines, DNA vaccines, subunit vaccines, inactivated virus vaccines, viral vector vaccine, live attenuated virus vaccines and mix and match vaccines will be discussed based on their mechanism, administration, storage, stability, safety and efficacy. The information was collected from various journals via electronic searches including PubMed, Science Direct, Google Scholar and the WHO platform. This review article includes a brief summary on the pathophysiology, epidemiology, mutant variants and management strategies related to COVID-19. Due to the continuous production and unsatisfactory understanding of novel variants of SARS-CoV-2, it is important to design an effective vaccine along with long-lasting protection against variant strains by eliminating the gaps through practical and theoretical knowledge. Consequently, it is mandatory to update the literature through previous and ongoing trials of vaccines tested among various ethnicities and age groups to gain a better insight into management strategies and combat complications associated with upcoming novel variants of SARS-CoV-2.

Evaluation of phytochemicals and antioxidant potential of a new polyherbal formulation TC-16: additive, synergistic or antagonistic?

BACKGROUND: Scientific literature has demonstrated the association of free radicals in the aetiology of various chronic diseases. Hence, the identification of potent antioxidants remains a useful task. The combination of multiple herbs in polyherbal formulations (PHF) is often associated with greater therapeutic efficacy due to synergistic interactions. However, antagonism can occur in natural product mixtures and the resultant antioxidant potential might not always be the additive value of the antioxidant properties of each component. In this study, we aimed to evaluate the phytochemicals, antioxidative potential and interaction among the herbs in TC-16, a new PHF comprising Curcuma longa L., Zingiber officinale var. Bentong, Piper nigrum L., Citrofortunella microcarpa (Bunge) Wijnands and Apis dorsata honey. METHODS: TC-16 was screened for phytochemicals. Phenolic and flavonoid contents of TC-16 and its individual ingredients were determined, followed by assessment of antioxidant properties using in vitro assays including 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC) and ß-carotene bleaching (BCB) assays. Interactions among the herbs were also investigated by calculating the difference in antioxidant activity and combination index. RESULTS: Alkaloids, flavonoids, terpenoids, saponins and glycosides were present in TC-16. TC-16 possessed the highest phenolic (46.14 ± 1.40 mg GAE/g) and flavonoid (132.69 ± 1.43 mg CE/g) contents following C. longa. Synergistic antioxidant activity among the herbs was evident in ORAC and BCB assays which uses mainly hydrogen atom transfer-based antioxidant mechanisms. CONCLUSIONS: TC-16 demonstrated roles in combating free radicals. In a PHF, synergistic interaction among the herbs is observed in some but not all mechanisms. Mechanisms showing synergistic interactions should be highlighted to maximise the beneficial property of the PHF.

Are Fermented Foods Effective against Inflammatory Diseases?

Fermented foods have been used over the centuries in various parts of the world. These foods are rich in nutrients and are produced naturally using various biological tools like bacteria and fungi. Fermentation of edible foods has been rooted in ancient cultures to keep food for preservation and storage for a long period of time with desired or enhanced nutritional values. Inflammatory diseases like rheumatoid arthritis, osteoarthritis, and chronic inflammatory pain are chronic disorders that are difficult to treat, and current treatments for these disorders fail due to various adverse effects of prescribed medications over a long period of time. Fermented foods containing probiotic bacteria and fungi can enhance the immune system, improve gastrointestinal health, and lower the risk of developing various inflammatory diseases. Foods prepared from vegetables by fermentation, like kimchi, sauerkraut, soy-based foods, or turmeric, lack proper clinical and translational experimental studies. The current review has focused on the effectiveness of various fermented foods or drinks used over centuries against inflammation, arthritis, and oxidative stress. We also described potential limitations on the efficacies or usages of these fermented products to provide an overarching picture of the research field.

Knema retusa is antibacterial and antibiofilm against antibiotic resistant Staphylococcus aureus and S. haemolyticus isolated in bovine mastitis.

This study aimed to assess antibacterial activity of Knema retusa wood extract (KRe) against antibiotic resistant staphylococci which are causative agents of bovine mastitis. From 75 cases of intramammary infections in dairy cows, 66 staphylococcal isolates were collected, including 11 Staphylococcus aureus isolates (17%) and 55 coagulase-negative staphylococci (83%). Sixty isolates (91%) formed strong biofilms. KRe had minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) against the isolates ranging 32-256 ug/mL and 64-512 ug/mL, respectively. Two-hour KRe exposures at 4×MIC, viabilities of S. aureus and S. haemolyticus decreased by 3 log10 compared to the control. Scanning EM (SEM) showed that KRe disrupted the bacterial cells of both species. KRe at 1/16×MIC significantly inhibited biofilm formation (P < 0.05) in both S. aureus and S. haemolyticus. At 1/2×MIC, S. aureus and S. haemolyticus biofilm inhibition ranged from 75 to 99%. Cells within established biofilms were disrupted 66-83% by KRe at 32×MIC. Moreover, 1/2×MIC KRe reduced bacterial adhesion to glass surfaces observed by SEM. According to GC-MS analysis, the major compound in KRe was endo-2-hydroxy-9,9-(ethylenedioxy)-1-carbethoxy bicyclo [3.3.1] nonane (E2N). Molecular docking analysis of E2N has a high affinity for staphylococcal accessory regulator A (SarA), binding free-energy - 6.40kcal/mol. The results suggested that KRe may have medicinal benefits by inhibiting the growth, biofilm, and adhesion of antibiotic resistant staphylococci isolated from bovine mastitis.

Anti-Acanthamoeba activity of a semi-synthetic mangostin derivative and its ability in removal of Acanthamoeba triangularis WU19001 on contact lens.

Garcinia mangostana L., also known as the mangosteen tree, is a native medicinal plant in Southeast Asia having a wide variety of pharmacologically active compounds, including xanthonoid mangostin. In this study, we examined the pharmacological activities of the selected semi-synthetic mangostin derivative, namely, amoebicidal activity, encystation inhibition, excystation activity, and removal capacity of adhesive Acanthamoeba from the surface of contact lens (CL). Among the three derivatives, C1 exhibited promising anti-Acanthamoeba activity against Acanthamoeba triangularis WU19001 trophozoites and cysts. SEM images displayed morphological changes in Acanthamoeba trophozoites, including the loss of acanthopodia, pore formation in the cell membrane, and membrane damage. In addition, the treated cyst was shrunken and adopted an irregular flat cyst shape. Under a fluorescence microscope, acridine orange and propidium iodide (AO/PI) staining revealed C1 induced condensation of cytoplasm and chromatin with the loss of cell volume in the treated trophozoites, while calcofluor white staining demonstrated the leakage of cell wall in treated cysts, leading to cell death. Interestingly, at the concentration ranges in which C1 showed the anti-Acanthamoeba effects (IC50 values ranging from 0.035-0.056 mg/mL), they were not toxic to Vero cells. C1 displayed the highest inhibitory effect on A. triangularis encystation at 1/16×MIC value (0.004 mg/mL). While C1 demonstrated the excystation activity at 1/128×MIC value with a high rate of 89.47%. Furthermore, C1 exhibited the removal capacity of adhesive Acanthamoeba from the surface of CL comparable with commercial multipurpose solutions (MPSs). Based on the results obtained, C1 may be a promising lead agent to develop a therapeutic for the treatment of Acanthamoeba infections and disinfectant solutions for CL.

Plant as an Alternative Source of Antifungals against Aspergillus Infections: A Review.

Aspergillus species consists of a group of opportunistic fungi that is virulent when the immunity of the host is compromised. Among the various species, Aspergillus fumigatus is the most prevalent species. However, the prevalence of fungal infections caused by non-fumigatus Aspergillus has been increasing. Polyenes, echinocandins and azoles are the three main classes of antifungal agents being used for the treatment of aspergillosis. Nevertheless, the incidence of resistance towards these three classes has been rising over the years among several Aspergillus spp. The side effects associated with these conventional antifungal agents have also limited their usage. This urges the need for the discovery of a safe and effective antifungal agent, which presents a major challenge in medicine today. Plants present a rich source of bioactive molecules which have been proven effective against a wide range of infections and conditions. Therefore, this present review intends to examine the current literature available regarding the efficacy and mechanism of action of plant extracts and their compounds against Aspergillus spp. In addition, novel drug delivery systems of plant extracts against Aspergillus spp. were also included in this review.

Antimicrobial Secondary Metabolites from the Mangrove Plants of Asia and the Pacific.

Microbes such as the White Spot Syndrome Virus account for severe losses in the shrimp farming industry globally. This review examines the literature on the mangrove plants of Asia and the Pacific with antibacterial, antifungal, or antiviral activities. All of the available data published on this subject were collected from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and a library search from 1968 to 2022. Out of about 286 plant species, 119 exhibited antimicrobial effects, and a total of 114 antimicrobial natural products have been identified including 12 with MIC values below 1 µg/mL. Most of these plants are medicinal. The mangrove plants of Asia and the Pacific yield secondary metabolites with the potential to mitigate infectious diseases in shrimp aquaculture.

Natural products from medicinal plants in Asia and the Pacific for RNA viruses: Hercules' fifth labour.

CONTEXT: The emergence of zoonotic viruses in the last decades culminating with COVID-19 and challenges posed by the resistance of RNA viruses to antiviral drugs requires the development of new antiviral drugs. OBJECTIVE: This review identifies natural products isolated from Asian and Pacific medicinal plants with in vitro and in vivo antiviral activity towards RNA viruses and analyses their distribution, molecular weights, solubility and modes of action. MATERIALS AND METHODS: All data in this review was compiled from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem and library search from 1961 to 2022. RESULTS: Out of about 350 molecules identified, 43 phenolics, 31 alkaloids, and 28 terpenes were very strongly active against at least one type of RNA virus. These natural products are mainly planar and amphiphilic, with a molecular mass between 200 and 400 g/mol and target viral genome replication. Hydroxytyrosol, silvestrol, lycorine, tylophorine and 12-O-tetradecanoylphorbol 13-acetate with IC50 below 0.01 µg/mL and selectivity index (S.I.) above 100 have the potential to be used for the development of anti-RNA virus leads. DISCUSSION AND CONCLUSIONS: The medicinal plants of Asia and the Pacific are a rich source of natural products with the potential to be developed as lead for the treatment of RNA viral infections.

Antibacterial and Antifungal Alkaloids from Asian Angiosperms: Distribution, Mechanisms of Action, Structure-Activity, and Clinical Potentials.

The emergence of multidrug-resistant bacteria and fungi requires the development of antibiotics and antifungal agents. This review identified natural products isolated from Asian angiosperms with antibacterial and/or antifungal activities and analyzed their distribution, molecular weights, solubility, and modes of action. All data in this review were compiled from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and a library search from 1979 to 2022. One hundred and forty-one antibacterial and/or antifungal alkaloids were identified during this period, mainly from basal angiosperms. The most active alkaloids are mainly planar, amphiphilic, with a molecular mass between 200 and 400 g/mol, and a polar surface area of about 50 Å2, and target DNA and/or topoisomerase as well as the cytoplasmic membrane. 8-Acetylnorchelerythrine, cryptolepine, 8-hydroxydihydrochelerythrine, 6-methoxydihydrosanguinarine, 2'-nortiliacorinine, pendulamine A and B, rhetsisine, sampangine, tiliacorine, tryptanthrin, tylophorinine, vallesamine, and viroallosecurinine yielded MIC ≤ 1 µg/mL and are candidates for the development of lead molecules.

Virulence Characteristics and Emerging Therapies for Biofilm-Forming Acinetobacter baumannii: A Review.

Acinetobacter species is one of the most prevailing nosocomial pathogens with a potent ability to develop antimicrobial resistance. It commonly causes infections where there is a prolonged utilization of medical devices such as CSF shunts, catheters, endotracheal tubes, and similar. There are several strains of Acinetobacter (A) species (spp), among which the majority are pathogenic to humans, but A. baumannii are entirely resistant to several clinically available antibiotics. The crucial mechanism that renders them a multidrug-resistant strain is their potent ability to synthesize biofilms. Biofilms provide ample opportunity for the microorganisms to withstand the harsh environment and further cause chronic infections. Several studies have enumerated multiple physiological and virulence factors responsible for the production and maintenance of biofilms. To further enhance our understanding of this pathogen, in this review, we discuss its taxonomy, pathogenesis, current treatment options, global resistance rates, mechanisms of its resistance against various groups of antimicrobials, and future therapeutics.

Solanaceae Family Phytochemicals as Inhibitors of 3C-Like Protease of SARS-CoV-2: An In Silico Analysis.

COVID-19, caused by the coronavirus SARS-CoV-2, emerged in late December 2019 in Wuhan, China. As of 8 April 2022, the virus has caused a global pandemic, resulting in 494,587,638 infections leading to 6,170,283 deaths around the world. Although several vaccines have received emergency authorization from USA and UK drug authorities and two more in Russia and China, it is too early to comment on the prolonged effectiveness of the vaccines, their availability, and affordability for the developing countries of the world, and the daunting task to vaccinate 7 billion people of the world with two doses of the vaccine with additional booster doses. As a result, it is still worthwhile to search for drugs and several promising leads have been found, mainly through in silico studies. In this study, we have examined the binding energies of several alkaloids and anthocyanin derivatives from the Solanaceae family, a family which contains common consumable vegetables and fruit items such as eggplant, pepper, and tomatoes. Our study demonstrates that Solanaceae family alkaloids such as incanumine and solaradixine, as well as anthocyanins and anthocyanidins, have very high predicted binding energies for the 3C-like protease of SARS-CoV-2 (also known as Mpro). Since Mpro is vital for SARS-CoV-2 replication, the compounds merit potential for further antiviral research towards the objective of obtaining affordable drugs.

Curcumin effect on Acanthamoeba triangularis encystation under nutrient starvation.

Background: Curcumin is an active compound derived from turmeric, Curcuma longa, and is known for its benefits to human health. The amoebicidal activity of curcumin against Acanthamoeba triangularis was recently discovered. However, a physiological change of intracellular pathways related to A. triangularis encystation mechanism, including autophagy in the surviving amoeba after curcumin treatment, has never been reported. This study aims to investigate the effect of curcumin on the survival of A. triangularis under nutrient starvation and nutrient-rich condition, as well as to evaluate the A. triangularis encystation and a physiological change of Acanthamoeba autophagy at the mRNA level. Methods: In this study, A. triangularis amoebas were treated with a sublethal dose of curcumin under nutrient starvation and nutrient-rich condition and the surviving amoebas was investigated. Cysts formation and vacuolization were examined by microscopy and transcriptional expression of autophagy-related genes and other encystation-related genes were evaluated by real-time PCR. Results: A. triangularis cysts were formed under nutrient starvation. However, in the presence of the autophagy inhibitor, 3-methyladenine (3-MA), the percentage of cysts was significantly reduced. Interestingly, in the presence of curcumin, most of the parasites remained in the trophozoite stage in both the starvation and nutrient-rich condition. In vacuolization analysis, the percentage of amoebas with enlarged vacuole was increased upon starvation. However, the percentage was significantly declined in the presence of curcumin and 3-MA. Molecular analysis of A. triangularis autophagy-related (ATG) genes showed that the mRNA expression of the ATG genes, ATG3, ATG8b, ATG12, ATG16, under the starvation with curcumin was at a basal level along the treatment. The results were similar to those of the curcumin-treated amoebas under a nutrient-rich condition, except AcATG16 which increased later. On the other hand, mRNA expression of encystation-related genes, cellulose synthase and serine proteinase, remained unchanged during the first 18 h, but significantly increased at 24 h post treatment. Conclusion: Curcumin inhibits cyst formation in surviving trophozoites, which may result from its effect on mRNA expression of key Acanthamoeba ATG-related genes. However, further investigation into the mechanism of curcumin in A. triangularis trophozoites arrest and its association with autophagy or other encystation-related pathways is needed to support the future use of curcumin.

Isolation and Characterization of Werneria Chromene and Dihydroxyacidissimol from Burkillanthus malaccensis (Ridl.) Swingle

The secondary metabolites of endemic plants from the Rutaceae family, such as Burkillanthusmalaccensis (Ridl.) Swingle from the rainforest of Malaysia, has not been studied. Burkillanthusmalaccensis (Ridl.) Swingle may produce antibacterial and antibiotic-potentiating secondary metabolites. Hexane, chloroform, and methanol extracts of leaves, bark, wood, pericarps, and endocarps were tested against bacteria by broth microdilution assay and their antibiotic-potentiating activities. Chromatographic separations of hexane extracts of seeds were conducted to investigate effective phytochemicals and their antibacterial activities. Molecular docking studies of werneria chromene and dihydroxyacidissiminol against SARS-CoV-2 virus infection were conducted using AutoDock Vina. The methanol extract of bark inhibited the growth of Staphylococcusaureus, Escherichiacoli, and Pseudomonasaeruginosa with the minimum inhibitory concentration of 250, 500, and 250 µg/mL, respectively. The chloroform extract of endocarps potentiated the activity of imipenem against imipenem-resistant Acinetobacterbaumannii. The hexane extract of seeds increased the sensitivity of P. aeruginosa against ciprofloxacin and levofloxacin. The hexane extract of seeds and chloroform extract of endocarps were chromatographed, yielding werneria chromene and dihydroxyacidissiminol. Werneria chromene was bacteriostatic for P.aeruginosa and P.putida, with MIC/MBC values of 1000 > 1000 µg/mL. Dihydroxyacidissiminol showed the predicted binding energies of −8.1, −7.6, −7.0, and −7.5 kcal/mol with cathepsin L, nsp13 helicase, SARS-CoV-2 main protease, and SARS-CoV-2 spike protein receptor-binding domain S-RBD. Burkillanthusmalaccensis (Ridl.) Swingle can be a potential source of natural products with antibiotic-potentiating activity and that are anti-SARS-CoV-2.