Search

In the past decade, researchers have focused on the emergence of drug resistance in fungal pathogens such as Candida albicans, also considered as pathobionts that occur harmlessly in the human body but could potentially be triggered to cause diseases. The increasing rate of antifungal resistance in commensal gut fungi is alarming and should be further investigated. Here, we report seven novel MLST (Multi Locus Sequence Typing) genotypes of multi-drug resistant C. albicans isolates obtained from participants of a community study in Segamat, a district in the state of Johor, Malaysia. A total of eight C. albicans were isolated from four individuals, which were found to express high resistance against fluconazole, itraconazole, voriconazole and 5-fluorocytosine antifungals. MLST was performed to assess the clonal relatedness of these drug resistant isolates among themselves and against other strains isolated from other geographical regions. The novel MLST C. albicans sequence types suggest significant genetic changes compared to previous genotypes. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s42770-021-00558-4.

In this study, the antibiotic enhancement and quorum sensing (QS) inhibition of allylpyrocatechol (APC) and methyl gallate (MG) isolated from leaves of Piper betle (betel) and leaf shoots of Anacardium occidentale (cashew), respectively, were compared. When applied with streptomycin and tested against Staphylococcus aureus and Pseudomonas aeruginosa, the effect of APC was additive while that of MG was synergistic. In terms of QS inhibition against Chromobacterium violaceum, both compounds were equally effective with violacein inhibition observed at concentrations of 60 μg/mL. We successfully increased the purity of APC in the methanol betel leaf extract from 13.2% to 31.5% w/w through solvent partitioning. This study is the first to document the anti-QS activity of APC, which is comparable to that of MG.

A Gram-negative, filamentous aerobic bacterium designated as strain Mgbs1T was isolated on 12 April 2017 from the subsurface soil and leaf litter substrate at the base of a Koompassia malaccensis tree in a tropical peat swamp forest in the northern regions of the state of Selangor, Malaysia (3° 39′ 04.7′ N 101° 17′ 43.7′′ E). Phylogenetic analyses based on the full 16S rRNA sequence revealed that strain Mgbs1T belongs to the genus Chitinophaga with the greatest sequence similarity to Chitinophaga terrae KP01T (97.65 %), Chitinophaga jiangningensis DSM27406T (97.58 %), and Chitinophaga dinghuensis DHOC24T (97.17 %). The major fatty acids of strain Mgbs1T (>10 %) are iso-C15 : 0, C16 : 1 ω5c and iso-C17 : 0 3-OH while the predominant respiratory quinone is menaquinone-7. Strain Mgbs1T has a complete genome size of 8.03 Mb, with a G+C content of 48.5 mol%. The DNA–DNA hybridization (DDH) score between strain Mgbs1T and C. jiangningensis DSM27406T was 15.9 %, while in silico DDH values of strain Mgbs1T against C. dinghuensis DHOC24T and C. terrae KP01T were 20.0 and 19.10% respectively. Concurrently, Average Nucleotide Identity (ANI) scores between strain Mgbs1T against all three reference strains are 73.2 %. Based on the phenotypic, chemotaxonomic, and phylogenetic consensus, strain Mgbs1T represents a novel species of the genus Chitinophaga , for which the name Chitinophaga extrema sp. nov. is proposed (=DSM 108835T=JCM 33276T).

Biological macromolecules are naturally occurring large cellular components responsible for a wide array of functions necessary for the growth and survival of living organisms. They also possess various bioactivities such as antimicrobial, antioxidant, antitumor, antiviral, antiinflammatory, antiproliferative, and hypoglycemic activities. The growing interest in bioactive macromolecules as potential therapeutical drugs has driven scientists to further study the association between their chemical structures and corresponding functions/activities. This chapter aims to provide a short overview on the structural features influencing the bioactivities of several biological macromolecules, namely l -amino acid oxidases, lysostaphin and metallo-β-lactamase-like lactonase and chitosan. As observed in this chapter, establishing the structure–activity relationship (SAR) can often prove to be challenging for macromolecules given the complexity of the three-dimensional organization level of proteins and the branched chains of the carbohydrates. Nevertheless, certain structural features influencing the bioactivities of macromolecules have been identified and could help to accelerate their development and application in the biomedical field. Indeed, a comprehensive understanding of biomacromolecule SARs remains necessary as information inferred from these studies may be crucial to many aspects of drug discovery and development, whether it is for primary screening or lead optimization, as well as for the designing of synthetic derivatives with improved properties.

In the biomedical field, there is growing interest in using human stem cell-derived neurons as in vitro models for pharmacological and toxicological screening of bioactive compounds extracted from natural products. Lignosus rhinocerus (Tiger Milk Mushroom) is used by indigenous communities in Malaysia as a traditional medicine to treat various diseases. The sclerotium of L. rhinocerus has been reported to have medicinal properties, including various bioactivities such as neuritogenic, anti-inflammatory, and anticancer effects. This study aims to investigate the neuroprotective activities of L. rhinocerus sclerotial extracts. Human embryonic stem cell (hESC)-derived neural lineages exposed to the synthetic glucocorticoid, dexamethasone (DEX), were used as the in vitro models. Excess glucocorticoids have been shown to adversely affect fetal brain development and impair differentiation of neural progenitor cells. Screening of different L. rhinocerus sclerotial extracts and DEX on the hESC-derived neural lineages was conducted using cell viability and neurite outgrowth assays. The neuroprotective effects of L. rhinocerus sclerotial extracts against DEX were further evaluated using apoptosis assays and Western blot analysis. Hot aqueous and methanol extracts of L. rhinocerus sclerotium promoted neurite outgrowth of hESC-derived neural stem cells (NSCs) with negligible cytotoxicity. Treatment with DEX decreased viability of NSCs by inducing apoptosis. Coincubation of L. rhinocerus methanol extract with DEX attenuated the DEX-induced apoptosis and reduction in phospho-Akt (pAkt) level in NSCs. These results suggest the involvement of Akt signaling in the neuroprotection of L. rhinocerus methanol extract against DEX-induced apoptosis in NSCs. Methanol extract of L. rhinocerus sclerotium exhibited potential neuroprotective activities against DEX-induced toxicity in hESC-derived NSCs. This study thus validates the use of human stem cell-derived neural lineages as potential in vitro models for screening of natural products with neuroprotective properties.

Although several studies have already been carried out in investigating the general profile of the gut mycobiome across several countries, there has yet to be an officially established baseline of a healthy human gut mycobiome, to the best of our knowledge. Microbial composition within the gastrointestinal tract differ across individuals worldwide, and most human gut fungi studies concentrate specifically on individuals from developed countries or diseased cohorts. The present study is the first culture-dependent community study assessing the prevalence and diversity of gut fungi among different ethnic groups from South East Asia. Samples were obtained from a multi-ethnic semi-rural community from Segamat in southern Malaysia. Faecal samples were screened for culturable fungi and questionnaire data analysis was performed. Culturable fungi were present in 45% of the participants' stool samples. Ethnicity had an impact on fungal prevalence and density in stool samples. The prevalence of resistance to fluconazole, itraconazole, voriconazole and 5-fluorocytosine, from the Segamat community, were 14%, 14%, 11% and 7% respectively. It was found that Jakun individuals had lower levels of antifungal resistance irrespective of the drug tested, and male participants had more fluconazole resistant yeast in their stool samples. Two novel point mutations were identified in the ERG11 gene from one azole resistant Candida glabrata, suggesting a possible cause of the occurrence of antifungal resistant isolates in the participant's faecal sample.

Zingiberaceae is a family that consists of many edible ginger plants. Etlingera pubescens (B.L.Burtt & R.M.Sm.) R.M.Sm. was studied for its antioxidant properties. Preliminary screening of the methanol extracts of its leaves, stems, rhizomes showed that the fresh leaves had the highest antioxidant activity, with total phenolic content (TPC), ascorbic acid equivalent antioxidant capacity (AEAC), and oxygen radical absorbance capacity (ORAC) values of 1020 ± 20 mg GAE/100 g, 1130 ± 30 mg AAE/100 g, and 140 ± 30 µmol TE/g, respectively. Subsequently, a diarylheptanoid, etlingerin, was isolated from the leaf methanol extract. When contrasted with curcumin (a well-known diarylheptanoid), etlingerin showed comparable free radical scavenging properties. However, using a cell-based antioxidant assay, etlingerin showed significantly better protective effects (with cellular antioxidant activity values as high as 84 ± 4%) than curcumin at all concentrations tested. In the cytoprotective study, only etlingerin could protect cells that were challenged with hydrogen peroxide. These effects might be explained by etlingerin's high lipophilicity and good free radical scavenging properties. Etlingerin was also found to be significantly less cytotoxic than curcumin (up to 10-fold, as determined using a MTT cell viability assay), thus suggesting its safety. The work showed that etlingerin has better antioxidant properties, hence highlighting its potential as a functional food component that could reduce the risks of oxidative stress-related diseases.

The present study exploits the potential of spent coffee grounds (SCGs) as a supplementary substrate for cultivating Pleurotus species. Increased levels of SCG in mixed substrate resulted in retardation of mycelial growth rate in a concentration-dependent manner. Subsequently, fruitification was inhibited when concentrations of SCG in the mixed substrate exceeded 30% (w/w) due to the relatively high phenolic and caffeine concentrations in SCG. Partial reductions in phenolic content and caffeine have been observed whenever SCG was present in the substrate; trace amounts of caffeine were also detected in fruiting bodies grown on all SCG-containing substrate mixtures. This finding suggests that Pleurotus spp. can reduce the levels of caffeine and phenolic compounds in SCG via bioaccumulation and biodegradation, respectively. Next, the supplementation of up to 20% (w/w) SCG did not significantly affect the proximate compositions, mineral contents, and fatty acid profiles in basidiocarps of both Pleurotus species compared to standard formulations.

Graphical abstract The effective high-calorie diet for metabolic syndrome induction is different between Sprague Dawley rats of different developmental stages. The post-weaning rats on high-fat diet for 8 weeks developed all phenotypes of metabolic syndrome while the adult rats on high-fat-high-sucrose diet merely became obese and hypertensive. The post-weaning rats on high-fat diet is a better and less time-consuming model for metabolic syndrome research., The present study aimed to examine the effects of the types of high-calorie diets (high-fat and high-fat-high-sucrose diets) and two different developmental stages (post-weaning and young adult) on the induction of metabolic syndrome. Male, post-weaning and adult (3- and 8-week old, respectively) Sprague Dawley rats were given control, high-fat (60% kcal), and high-fat-high-sucrose (60% kcal fat + 30% sucrose water) diets for eight weeks (n = 6 to 7 per group). Physical, biochemical, and transcriptional changes as well as liver histology were noted. Post-weaning rats had higher weight gain, abdominal fat mass, fasting glucose, high density lipoprotein cholesterol, faster hypertension onset, but lower circulating advanced glycation end products compared to adult rats. This is accompanied by upregulation of peroxisome proliferator-activated receptor (PPAR) α and γ in the liver and receptor for advanced glycation end products (RAGE) in the visceral adipose tissue. Post-weaning rats on high-fat diet manifested all phenotypes of metabolic syndrome and increased hepatic steatosis, which are linked to increased hepatic and adipocyte PPARγ expression. Adult rats on high-fat-high-sucrose diet merely became obese and hypertensive within the same treatment duration. Thus, it is more effective and less time-consuming to induce metabolic syndrome in male post-weaning rats with high-fat diet compared to young adult rats. As male rats were selectively included into the study, the results may not be generalisable to all post-weaning rats and further investigation on female rats is required.

Species of fungi belonging to the order Mucorales can be found everywhere in the environment. Gilbertella persicaria, which belongs to this order, have often been isolated from fruits and in water systems. However, there has been no report of isolation of this fungus from human samples. During a gut mycobiome study, from the Segamat community, Gilbertella persicaria was isolated from a human fecal sample and was characterized through a series of morphological assessment, biochemical tests, and molecular techniques. The isolate produced a white velvety surface that turned grayish after 24 h. Although no biofilm production was observed, the results indicated that the isolate could form calcium oxalate crystals, produced urease, and was resistant to low pH. The isolate was sensitive to amphotericin but resistant to voriconazole and itraconazole. The features of this fungus that could help in its survival in the human gut are also discussed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s42770-020-00323-z) contains supplementary material, which is available to authorized users.

Widely used throughout the world as traditional medicine for treating a variety of diseases ranging from cancer to microbial infections, members of the Tradescantia genus show promise as sources of desirable bioactive compounds. The bioactivity of several noteworthy species has been well-documented in scientific literature, but with nearly seventy-five species, there remains much to explore in this genus. This review aims to discuss all the bioactivity-related studies of Tradescantia plants and the compounds discovered, including their anticancer, antimicrobial, antioxidant, and antidiabetic activities. Gaps in knowledge will also be identified for future research opportunities.

Aims The aim of this study was to investigate the antimicrobial activities of Etlingera pubescens, and to isolate and identify the antimicrobial compound. Methods and results The crude extracts of E. pubescens were obtained through methanol extraction, and evaluated for antimicrobial activities. From this extract, 1,7-bis(3,4-dihydroxyphenyl)heptan-3-yl acetate (etlingerin) was isolated. When compared to curcumin (a compound with a similar chemical structure), etlingerin showed twofold lower minimum inhibitory concentration values while also being bactericidal. Through time kill assay, etlingerin showed rapid killing effects (as fast as 60 min) against the Gram-positive bacteria (Staphylococcus aureus ATCC 43300 and Bacillus subtilis ATCC 8188). Further assessment revealed that etlingerin caused leakage of intracellular materials, therefore suggesting alteration in membrane permeability as its antimicrobial mechanism. Cytotoxicity study demonstrated that etlingerin exhibited approximately 5- to 12-fold higher IC50 values against several cell lines, as compared to curcumin. Conclusions Etlingerin isolated from E. pubescens showed better antibacterial and cytotoxic activities when compared to curcumin. Etlingerin could be safe for human use, though further cytotoxicity study using animal models is needed. Significance and impact of the study Etlingerin has a potential to be used in treating bacterial infections due to its good antimicrobial activity, while having potentially low cytotoxicity.

The search for new and novel drugs is never-ending. Despite advances in synthetic chemistry, nature nevertheless remains as an important resource for the drug discovery. For decades, a routine screening of ethnopharmacologically important plants, followed by chromatographic isolation has been the basis of bioprospecting. Recent advances in bioinformatics and in silico screening have further improved our rate and likelihood of finding medicinal metabolites. Multiple classes of naturally occurring plant secondary metabolites, such as polyphenols, terpenoids, and alkaloids have been proven to possess significant medicinal potentials including antioxidant, anti-allergic, anti-inflammatory, anticancer, antihypertensive, and antimicrobial activities. The compounds of interest are often used as a basis or inspiration for semisynthetic drugs with improved pharmacokinetic and pharmacodynamic parameters. However, when a new biologically active compound has been identified, further in vivo testing and clinical trials may not reflect results seen in vitro. As with any promising fields, pitfalls and drawbacks are inevitable; these include poor bioavailability and unknown pharmacodynamics/pharmacokinetics. The drug development is further complicated by other challenges, such as processing, formulation, scaling up, and intellectual property protection. This chapter aims to discuss on the prospects of plant metabolites leading to drug discovery, along with the process and outcomes of testing and the potential pitfalls or challenges faced by researchers and the pharmaceutical industry in this endeavour.

The effects of oven-drying at 50 and 100C, sun-drying and ambient air-drying at 24 ± 1C on the antioxidant properties (AOPs) of mulberry (Morus alba L.) leaves were studied. Except for leaves oven-dried at 50C which showed minimal AOP changes, leaves dried under other conditions resulted in a significant decrease in AOP. Fresh mulberry leaves contained low oxidative enzyme activities (polyphenol oxidase [PPO]: 1.40 ± 0.58 ΔA435/min/g of fresh leaves and peroxidase: 1.59 ± 0.42 ΔA418/min/g of fresh leaves) which were reduced to nonmeasureable or lower values when they were dried at 50, 100C and blanched in boiling water. The major factor causing AOP decrease in thermally treated leaves (oven-drying at 100C and sun-drying) was due to thermal degradation but the decrease in AOP for ambient air-dried leaves was associated with the presence of PPO. Overall, oven-drying at 50C was the most preferred drying method. Practical Applications Mulberry with excellent free radical scavenging, antioxidant, anticancer and anti-hyperglycemic properties has long been used as traditional medicine and health food product. Generally, mulberry leaves are processed and consumed as tea. Drying, which helps preserve the nutrient contents of mulberry leaves, is an important method in mulberry tea processing. In order to exploit mulberry leaves more scientifically and efficiently for commercial purpose, the present study serves as an important work in providing insights into how oxidative enzymes and thermal stability of antioxidants in mulberry leaves affect the antioxidant properties when subjected to different drying conditions. The optimum drying condition found in this study will be beneficial to the tea processing industry.

The present study aimed to outline the physiological and metabolic disparity between chow- and purified ingredient-based high-fat diets and their efficacy in the induction of metabolic syndrome (MetS). Male, 3-week-old Sprague Dawley rats were randomly assigned to chow-based control diet, chow-based high-fat diet, purified control diet, and purified high-fat diet for 12 weeks. Physical and biochemical changes were documented. Chow-based diets, irrespective of the lipid content, resulted in significantly lower weight gain and organ weight compared to purified ingredient-based diets. Circulating insulin, total proteins, albumin, and certain lipid components like the triglycerides, total cholesterol, and high-density lipoprotein-cholesterol were also lower in the chow-based diet groups. Both chow- and purified high-fat diets induced central obesity, hypertension, and hyperglycaemia, but the latter was associated with earlier onset of the metabolic aberrations and additionally, dyslipidaemia. In conclusion, purified high-fat diet is a better diet for MetS induction in rats. PRACTICAL APPLICATIONS: Modeling metabolic syndrome is commonly accomplished with the use of chow- or purified ingredient diets enriched with carbohydrates and/or lipids, but the differences and associated drawbacks are unclear. This study highlights that chow- or modified chow-based diets have a tendency to introduce unwanted metabolic changes which are inconsistent with the progression of metabolic syndrome. Thus, the use of these diets in metabolic disease study should be avoided. On the other hand, purified high-fat diet which can effectively induce the features of metabolic syndrome is highly recommended.

Aims To investigate the antimicrobial properties of Etlingera coccinea and Etlingera sessilanthera and to isolate and identify the antimicrobial compounds. Methods and results Extracts were obtained via sequential solvent extraction method using hexane, dichloromethane, ethyl acetate, methanol and water. Antimicrobial activity testing was done using broth microdilution assay against 17 strains of bacteria. The leaf hexane extract of E. coccinea and rhizome hexane extract of E. sessilanthera showed best antimicrobial activities, with minimum inhibitory concentration (MIC) values ranging from 0·016 to 1 mg ml-1 against Gram-positive bacteria. From these active extracts, two antimicrobials were isolated and identified as trans-2-dodecenal and 8(17),12-labdadiene-15,16-dial with MIC values ranging from 4 to 8 μg ml-1 against Bacillus cereus, Bacillus subtilis and Staphylococcus aureus. Conclusion Etlingera coccinea and E. sessilanthera demonstrated good antimicrobial activities against clinically relevant bacteria strains. The antimicrobial compounds isolated showed low MIC values, hence suggesting their potential use as antimicrobial agents. Significance and impact of the study This study is the first to identify the potent antimicrobials from these gingers. The antimicrobials isolated could potentially be developed further for use in treatment of bacterial infections. Also, this study warrants further research into other Etlingera species in search for more antimicrobial compounds.

Commelinaceae is a family of herbaceous flowering plants with many species used in ethnobotany, particularly in South America. However, thus far reports of their bioactivity are few and far between. The primary aim of this study was to quantify the antioxidant and antibacterial activity of five Commelinaceae methanolic leaf extracts. The antioxidant content was evaluated by the total phenolic content (TPC), total tannin content (TTC), and total flavonoid content (TFC) assays. The antioxidant activities measured were DPPH free radical scavenging (FRS), ferric reducing power (FRP), and ferrous ion chelating (FIC), of the five plants, the methanolic leaf extract of Tradescantia zebrina showed the highest antioxidant content and activity, and exhibited antibacterial activity against six species of Gram-positive and two species of Gram-negative bacteria in a range of 5–10 mg/mL based on the broth microdilution method.

Antioxidant properties (AOP) of thirteen tropical and five temperate herbal teas were screened. Comparisons were made with green, oolong and black teas of Camellia sinensis. The AOP studied were total phenolic content, radical-scavenging activity, ferric-reducing power and ferrous ion-chelating (FIC) ability. Tropical herbal teas were more diverse in types and more variable in AOP values than temperate herbal teas. Herbal teas generally had lower antioxidant values than teas of C. sinensis. Exceptions were lemon myrtle, guava and oregano teas with AOP comparable to black teas. FIC ability of mint and peppermint teas was significantly stronger than all C. sinensis teas.

Background For generations, the rhizomes of Drynaria ferns have been used as traditional medicine in Asia. Despite this, the bioactivities of Drynaria rhizomes and leaves have rarely been studied scientifically. Methods This study evaluates the antioxidant properties of the methanolic extracts of the fertile fronds and rhizomes from three species in this genus: Drynaria quercifolia, Drynaria rigidula and Drynaria sparsisora. The phenolic and flavonoid contents of the samples were respectively quantified with the total phenolic content (TPC) and total flavonoid content (TFC) assays, while the antioxidant activities were determined via measuring the DPPH radical scavenging activity (FRS), ferric reducing power (FRP), ferrous ion chelating (FIC) activity and lipid peroxidation inhibition (LPI). The tyrosinase inhibition activity of all three species was also reported. Results The fertile fronds of D. quercifolia were found to exhibit the highest overall TPC (2939 ± 469 mg GAE/100 g) and antioxidant activity amongst all the samples, and the fertile fronds of D. quercifolia and D. rigidula exhibited superior TPC and FRP compared to their rhizomes, despite only the latter being widely used in traditional medicine. The fronds of D. quercifolia had high tyrosinase inhibition activity (56.6 ± 5.0 %), but most of the Drynaria extracts showed unexpected tyrosinase enhancement instead, particularly for D. sparsisora’s fronds. Conclusion The high bioactivity of the fertile fronds in the fern species indicate that there is value in further research on the fronds of ferns which are commonly used mostly, or only, for their rhizomes.