Evaluation of in vitro free radical scavenging potential of Streptomyces sp. AM-S1 culture filtrate

Phytochemical Evaluation and Antioxidant Potential of Polyherbal Extract Mixture-an In Vitro and In Silico Study

Standardisation of polyherbal formulations plays a key role in estimating the quality and safety of drugs. In this study, a novel polyherbal formulation was prepared for the treatment of diabetic nephropathy and it was attempted to evaluate for its safety and efficacy against free radicals. To ascertain the safety of the formulation, individual herbs and polyherbal formulation have been screened for microbial load, heavy metals, pesticide residues and aflatoxins according to Ayush guidelines. Phytochemical analysis was carried out using standard procedures and GCMS analysis to identify the bioactive compounds. Antioxidant methods such as DPPH, nitric oxide, hydrogen peroxide, hydroxyl and superoxide radical scavenging assays were undertaken. To predict the mechanism behind the antioxidant efficacy, a molecular docking analysis was performed against Keap1/Nrf2 (PDB ID: 2FLU) protein using AutoDock Vina software. Phytochemical analysis showed the presence of alkaloids, tannins, flavones, glycosides, polyphenols, phytosterols and saponins. The results of in vitro antioxidant studies showed increase in percentage inhibition with increase in concentration and found no significant difference compare with standards. Among the 15 bioactive compounds identified from GCMS analysis, guanosine showed high binding affinity with Keap1/Nrf2 and interacting with similar residues as that of standard ascorbic acid which is analysed through molecular docking. Based on the results, it has been concluded that the safety parameters of polyherbal formulation were found within specified limits of Ayush guidelines and its efficacy against oxidative stress plays an effective role to treat diabetic nephropathy due to its synergistic antioxidant effect.

Quercus salicina Blume: Research progress in chemistry and pharmacodynamics (1959-2021)

The crude extracts of different parts (leaves and shoots) of Quercus salicina  Blume (QS) have shown considerable effect in urolithiasis. QS has been widely used in clinical practice and has attracted great research interest The relevant published literature, however, reveals only partial education of its chemical components and bio-active mechanisms, and only two review papers have summarized the QS research progress. In this review, a comprehensive and systematic review of chemistry and pharmacodynamics of QS was carried out using the international authoritative databases (1959-2021), focusing on phenols and flavonoids, and their effect such as urinary stone dissolution, anti-inflammatory, anti-diabetes, anti-bacterial, antioxidant, and anti-allergy activities as well as toxic effects .The aim of review is to provide the most recent and effective literature support for further basic research and application development.

TL15 of Arthrospira platensis sulfite reductase scavenges free radicals demonstrated in oxidant induced larval zebrafish (Danio rerio) model

The antioxidant role of sulfite reductase (SiR) derived from Arthrospira platensis (Ap) was identified through a short peptide, TL15. The study showed that the expression of ApSiR was highly expressed on day ten due to sulfur deprived stress in Ap culture. TL15 peptide exhibited strong antioxidant activity when evaluated using antioxidant assays in a concentration ranging from 7.8 and 125 μM. Further, the cytotoxicity of TL15 peptide was investigated, even at the higher concentration (250 μM), TL15 did not exhibit any toxicity, when tested in vitro using human leucocytes. Moreover, a potential reduction in reactive oxygen species (ROS) production was observed due to the treatment of TL15 peptide (>15.6 μM) to H₂O₂ exposed leucocytes. For the in vivo assessment of TL15 toxicity and antioxidant ability, experiments were performed in zebrafish (Danio rerio) larvae to analyse the developmental toxicity of TL15 peptide. Results showed that, exposure to TL15 peptide in tested concentrations ranging from 10, 20, 40, and 80 μM, did not affect the development and physiological parameters of the zebrafish embryo/larvae such as morphology, survival, hatching and heart rate. Fluorescent assay was performed using DCFH-DA (2,7-dichlorodihydrofluorescein diacetate) to examine the production of intracellular reactive oxygen species (ROS) in zebrafish treated with TL15 peptide during the embryo-larval stages. Fluorescent images showed that pre-treatment with TL15 peptide to attenuate the H₂O₂ induced ROS levels in the zebrafish larvae in a dose-dependent manner. Further to uncover the underlying biochemical and antioxidant mechanism, the enzyme activity of superoxide dismutase (SOD), catalase (CAT) and lipid peroxidation (LPO) levels were studied in zebrafish larvae. TL15 pre-treated groups showed enhanced antioxidant enzyme activity, while the hydrogen peroxide (H₂O₂) exposed larvae showed significantly diminished activity. Overall results from the study revealed that, TL15 act as a potential antioxidant molecule with dose-specific antioxidant property. Thus, TL15 peptide could be an effective and promising source for biopharmaceutical applications.

Bacillus amyloliquefaciens RWL-1 as a New Potential Strain for Augmenting Biochemical and Nutritional Composition of Fermented Soybean

Soybean (Glycine max L.) is a good source of natural antioxidants and commonly consumed as fermented products such as cheonggukjang, miso, tempeh, and sufu in Asian countries. The aim of the current study was to examine the influence of novel endophytic bacterial strain, Bacillus amyloliquefaciens RWL-1 as a starter for soybean fermentation. During fermentation, the cooked soybeans were inoculated with different concentrations (1%, 3%, and 5%) of B. amyloliquefaciens RWL-1. The changes in 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activities, total phenolic contents, isoflavones (Daidzin, Genistin, Glycitin, Daidzein, Glycitein, and Genistein), amino acids (aspartic acid, threonine, serine, glutamic acid, glycine, alanine, cysteine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine, arginine, and proline) composition, and minerals (calcium, copper, iron, potassium, magnesium, manganese, sodium, nickel, lead, arsenic, and zinc) were investigated. The level of antioxidants, total phenolic contents, isoflavones, and total amino acids were higher in fermented soybean inoculated with 1% B. amyloliquefaciens RWL-1 after 60 h of fermentation as compared to control, 3% and 5% B. amyloliquefaciens RWL-1. Additionally, fermented soybean inoculated with 5% B. amyloliquefaciens RWL-1 showed the highest values for mineral contents. Changes in antioxidant activities and bioactive compounds depended on the concentration of the strain used for fermentation. From these results, we conclude that fermented soybean has strong antioxidant activity, probably due to its increased total phenolic contents and aglycone isoflavone that resulted from fermentation. Such natural antioxidants could be used in drug and food industries and can be considered to alleviate oxidative stress.

Antimicrobial and Antioxidant Effects of a Forest Actinobacterium V002 as New Producer of Spectinabilin, Undecylprodigiosin and Metacycloprodigiosin

The aim of the study is the research and identification of a Streptomyces strain as a new producer of spectinabilin, undecylprodigiosin and metacycloprodigiosin. Among 54 actinomycete isolates isolated from El-Ogbane forest soils in Algeria, only one isolate, designated V₀₀₂, was selected for its ability to produce prodigiosins. The selected strain was analysed for its ability to produce three different secondary metabolites as well as their biological activities. V₀₀₂ belongs to the Streptomyces genus and has significant antimicrobial and antioxidant activities. The taxonomic position of V₀₀₂ by 16S rRNA sequence analysis showed a similarity of 99.93% with Streptomyces lasiicapitis DSM 103124^T and 98.96% with Streptomyces spectabilis DSM 40512^T. Fractionation of crude secondary metabolites produced by the strain using HPLC-MS revealed the presence of spectinabilin, undecylprodigiosin and metacycloprodigiosin, which demonstrated significant activity. Strain V₀₀₂ is considered a new producer of spectinabilin, undecylprodigiosin and metacycloprodigiosin with significant antimicrobial and antioxidant activity.

Characterization and antifungal activity of the yellow pigment produced by a Bacillus sp. DBS4 isolated from the lichen Dirinaria agealita

This study emphasis the production of yellow pigment from endolichenic Bacillus sp. isolated from the lichen Dirinaria aegialita (Afzel. ex Ach.) B.J. Moore. Yellow pigment-producing twenty different strains were investigated. The hyperactive pigment-producing bacterial strain was identified as Bacillus gibsonii based on 99 % sequence similarity. Maximum bacterial pigment production appeared in Luria Bertani medium. Methanol extraction of the pigment and its partial purification using TLC was carried out. Furthermore, isolated pigments were characterized using UV-visible spectroscopy, FTIR spectroscopy, and GC-MS results related to the possibility of the carotenoid occurrence. The pigment also exhibited efficient antifungal activity against selected fungal pathogens of economic importance. Likewise, the pigment extract evaluated for the total antioxidant potential using Phosphomolybdenum and Ferric reducing antioxidant power assay and the results represented in Ascorbic Acid Equivalent (AAE)- 21.45 ± 1.212 mg/mL. The SC₅₀ of the pigment extract found to be 75.125 ± 0.18 µg/ml determined by the ABTS assay.

Essential oils and ethanol extract from Camellia nitidissima and evaluation of their biological activity

Camellia nitidissima, a well-known species of yellow Camellia, has undergone commercial cultivation as a new tea resource recently. Herein, the composition, antioxidant and antimicrobial activities of the essential oil and ethanol extract of C. nitidissima were investigated. The essential oils from the leaves and flowers of C. nitidissima were obtained by hydro-distillation. A total of 56 and 34 constituents accounting for 77.5 and 96.8% of the oils were identified by GC-MS. Linalool (35.8%), phytol (7.9%), cis-geranyl acetone (7.3%) and methyl salicylate (6.8%) were found to be the primary components in the leaf oil, while the flower oil was rich in α-eudesmol (34.3%), γ-eudesmol (31.5%) and linalool (11.1%). The ethanol extract of C. nitidissima leaves contained 281.04 mg gallic acid equivalent/g of total phenols. The antioxidant activities of the two oils and extract were evaluated by DPPH and ABTS radical-scavenging assays. The IC50 values varied from 17.4 (extract) to 720.3 μg/mL (flower oil) for DPPH and from 28.8(extract) to 889.6 μg/mL (flower oil) for ABTS. Both essential oils exhibited moderate antioxidant activities, and the extract possessed strong effects close to ascorbic acid. Additionally, the antimicrobial activities of the oils and extract against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa were evaluated by agar dilution assay. No considerable bactericidal activities were observed for either essential oil or extract compared with ampicillin and tobramycin standards. The results indicated the extract was more efficient than the two essential oils against S. aureus (MIC = 0.625 mg/mL) and B. subtilis (MIC = 1.25 mg/mL).

Antibacterial and Antioxidant Activities of Novel Actinobacteria Strain Isolated from Gulf of Khambhat, Gujarat

Bacterial secondary metabolites possess a wide range of biologically active compounds including antibacterial and antioxidants. In this study, a Gram-positive novel marine Actinobacteria was isolated from sea sediment which showed 84% 16S rRNA gene sequence (KT588655) similarity with Streptomyces variabilis (EU841661) and designated as Streptomyces variabilis RD-5. The genus Streptomyces is considered as a promising source of bioactive secondary metabolites. The isolated novel bacterial strain was characterized by antibacterial characteristics and antioxidant activities. The BIOLOG based analysis suggested that S. variabilis RD-5 utilized a wide range of substrates compared to the reference strain. The result is further supported by statistical analysis such as AWCD (average well color development), heat-map and PCA (principal component analysis). The whole cell fatty acid profiling showed the dominance of iso/anteiso branched C15–C17 long chain fatty acids. The identified strain S. variabilis RD-5 exhibited a broad spectrum of antibacterial activities for the Gram-negative bacteria (Escherichia coli NCIM 2065, Shigella boydii NCIM, Klebsiella pneumoniae, Enterobacter cloacae, Pseudomonas sp. NCIM 2200 and Salmonella enteritidis NCIM), and Gram-positive bacteria (Bacillus subtilis NCIM 2920 and Staphylococcus aureus MTCC 96). Extract of S. variabilis strain RD-5 showed 82.86 and 89% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and metal chelating activity, respectively, at 5.0 mg/mL. While H₂O₂ scavenging activity was 74.5% at 0.05 mg/mL concentration. Furthermore, polyketide synthases (PKSs types I and II), an enzyme complex that produces polyketides, the encoding gene(s) detected in the strain RD-5 which may probably involve for the synthesis of antibacterial compound(s). In conclusion, a novel bacterial strain of Actinobacteria, isolated from the unexplored sea sediment of Alang, Gulf of Khambhat (Gujarat), India showed promising antibacterial activities. However, fractionation and further characterization of active compounds from S. variabilis RD-5 are needed for their optimum utilization toward antibacterial purposes.

Continuing hunt for endophytic actinomycetes as a source of novel biologically active metabolites

Drug-resistant pathogens and persistent agrochemicals mount the detrimental threats against human health and welfare. Exploitation of beneficial microorganisms and their metabolic inventions is most promising way to tackle these two problems. Since the successive discoveries of penicillin and streptomycin in 1940s, numerous biologically active metabolites have been discovered from different microorganisms, especially actinomycetes. In recent years, actinomycetes that inhabit unexplored environments have received significant attention due to their broad diversity and distinctive metabolic potential with medical, agricultural and industrial importance. In this scenario, endophytic actinomycetes that inhabit living tissues of plants are emerging as a potential source of novel bioactive compounds for the discovery of drug leads. Also, endophytic actinomycetes are considered as bio-inoculants to improve crop performance through organic farming practices. Further efforts on exploring the endophytic actinomycetes associated with the plants warrant the likelihood of discovering new taxa and their metabolites with novel chemical structures and biotechnological importance. This mini-review highlights the recent achievements in isolation of endophytic actinomycetes and an assortment of bioactive compounds.

Characterization and determination of antioxidant components in the leaves of Camellia chrysantha (Hu) Tuyama based on composition-activity relationship approach

Camellia chrysantha (Hu) Tuyama (CCT), an ornamental plant possessing antioxidant activity, has been infused as tea and drank for its health benefits. The antioxidant components in CCT, however, had not been clearly characterized. To quickly identify the antioxidant constituents of CCT, a composition–activity relationship strategy based on ultra high-pressure liquid chromatography coupled with linear ion trap hybrid orbitrap mass spectrometry and orthogonal partial least-squares method has been applied. As a result, 16 variables were found to make significant contributions to the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. Six of them were identified as catechin (1), epicatechin (5), vitexin (8), isovitexin (10), quercetin-7-O-β-D-glucopyranoside (12) and kaempferol (16). The strength of 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity was found to be 12 > 1 > 5 > 16 > 8 > 10 by validation test. Meanwhile, a liquid chromatography-electrospray ionization-mass spectrometry method was established for quantitative determination of six marker compounds in CCT samples from different preparations. The validation of the method, including linearity, sensitivity (limitation of detection and limitation of quantification), repeatability, precision, stability, and recoveries, was carried out and demonstrated to meet the requirements of quantitative analysis. This is the first report on the comprehensive characterization and determination of chemical constituents in CCT by ultra high-pressure liquid chromatography coupled with linear ion trap hybrid orbitrap mass spectrometry. The results indicate that the composition–activity relationship approach may be a useful method for the discovery of active constituents in natural plants and the quality control of medicinal herbs.