Enhancement of Antioxidant and Antibacterial Activities of Salvia miltiorrhiza Roots Fermented with Aspergillus oryzae

Natural Antimicrobials: A Reservoir to Contrast Listeria monocytogenes

Natural environments possess a reservoir of compounds exerting antimicrobial activity that are forms of defence for some organisms against others. Recently, they have become more and more attractive in the food sector due to the increasing demand for natural compounds that have the capacity to protect food from pathogenic microorganisms. Among foodborne pathogens, Listeria monocytogenes can contaminate food during production, distribution, or storage, and its presence is especially detected in fresh, raw food and ready-to-eat products. The interest in this microorganism is related to listeriosis, a severe disease with a high mortality rate that can occur after its ingestion. Starting from this premise, the present review aims to investigate plant extract and fermented plant matrices, as well as the compounds or mixtures of compounds produced during microbial fermentation processes that have anti-listeria activity.

Quantitative Phytochemical Profile and In Vitro Antioxidant Properties of Ethyl Acetate Extracts of Xerophyta spekei (Baker) and Grewia tembensis (Fresen)

Overproduction of free radicals in excess of antioxidants leads to oxidative stress which can cause harm to the body. Conventional antioxidants have drawbacks and are believed to be carcinogenic. The present study seeked to confirm folklore use and validate the antioxidant potentials of Grewia tembensis and Xerophyta spekei which have been widely used in the Mbeere community as medicinal plants. Antioxidant properties were determined through scavenging effects of diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide radicals as well as iron chelating effects. The data obtained was assayed in comparison to the standards (Ascorbic acid and EDTA). Ascorbic acid had a significantly greater DPPH radical scavenging property with an inhibitory concentration (IC₅₀) value of 20.54 ± 2.24 µg/mL in comparison to the plant extracts, which had IC₅₀ values of 33.00 ± 1.47 µg/mL, 69.66 ± 1.01 µg/mL and 86.88 ± 2.64 µg/mL for X. spekei, G. tembensis leaf and G. tembensis stem bark extracts, respectively. EDTA demonstrated a significantly greater iron chelating effect having a significantly lesser IC₅₀ value of 25.05 ± 0.79 µg/mL as opposed to 43.56 ± 0.46 µg/mL, 89.78 ± 0.55 µg/mL, and 120.70 ± 0.71 µg/mL for X. spekei, G. tembensis leaf, and G. tembensis stem bark extracts respectively. Additionally, ascorbic acid also exhibited stronger hydrogen peroxide radical scavenging effect than the studied extracts. Generally, X. spekei extract had higher antioxidant activities as compared to both the leaf and stem bark extracts of G. tembensis. The phytochemical screening demonstrated the presence of secondary metabolites associated with antioxidant properties. The present study therefore, recommends ethno medicinal and therapeutic use of G. tembensis and X. spekei in the treatment and management of oxidative stress related infections.

GC-MS Analysis, Antibacterial and Antioxidant Potential of Ethyl Acetate Leaf Extract of Senna singueana (Delile) Grown in Kenya

Bacterial diseases are a leading cause of mortality and morbidity globally. During bacterial diseases, an elevation of host immune response occurs, which involves the production of free radicals in response to the bacterial infection. The overproduction of free radicals in excess of the antioxidants leads to oxidative stress. Conventional antibiotics are linked to side effects such as hypersensitivity reactions in addition to bacterial pathogens developing resistance against them. Artificial antioxidants are said to be carcinogenic. This study sought to confirm folklore use and validate the antibacterial and antioxidant potential of Senna singueana which has been widely used in the Mbeere community. The in vitro antibacterial potentials of the plant extract were investigated on Bacillus subtilis ATCC 21332, Escherichia coli ATCC 25922, Salmonella typhi ATCC 1408, and Staphylococcus aureus ATCC 25923. Ciprofloxacin (100 µg/ml) drug was used as a standard reference, whereas 5% DMSO was used as a negative reference. The antibacterial tests included disc diffusion and minimum inhibitory and bactericidal concentrations. S. singueana ethyl acetate extract showed broad-spectrum potential against tested bacterial microbes producing mean zones of inhibition (MZI) from 07.67 ± 0.33 to 17.67 ± 0.33 mm. The extract demonstrated a greater effect on Gram-positive than Gram-negative bacterial pathogens. Antibacterial properties of ciprofloxacin were significantly greater in comparison to plant extract in all the dilutions ( $p<0.05$ ), while 5% DMSO was inactive against all the tested bacteria. MBC values were greater than MIC values. Antioxidant properties of the extract were determined through scavenging effects of DPPH and hydroxyl radicals (•OH) as well as ferric reducing antioxidant potential (FRAP) assay. S. singueana demonstrated effects against all radicals formed. Additionally, the extract exhibited ferric reducing abilities. The extract also contained various phytocompounds with known antibacterial and antioxidant properties. This study recommends the therapeutic use of S. singueana as an antibacterial as well as an antioxidant agent.

Enzymatic Synthesis of Resveratrol α-Glucoside by Amylosucrase of Deinococcus geothermalis

Glycosylation of resveratrol was carried out by using the amylosucrase of Deinococcus geothermalis, and the glycosylated products were tested for their solubility, chemical stability, and biological activities. We synthesized and identified these two major glycosylated products as resveratrol-4'-O-α-glucoside and resveratrol-3-O-α-glucoside by nuclear magnetic resonance analysis with a ratio of 5:1. The water solubilities of the two resveratrol-α-glucoside isomers (α-piceid isomers) were approximately 3.6 and 13.5 times higher than that of β-piceid and resveratrol, respectively, and they were also highly stable in buffered solutions. The antioxidant activity of the α-piceid isomers, examined by radical scavenging capability, showed it to be initially lower than that of resveratrol, but as time passed, the α-piceid isomers' activity reached a level similar to that of resveratrol. The α-piceid isomers also showed better inhibitory activity against tyrosinase and melanin synthesis in B16F10 melanoma cells than β-piceid. The cellular uptake of the α-piceid isomers, which was assessed by ultra-performance liquid chromatography (UPLC) analysis of the cell-free extracts of B16F10 melanoma cells, demonstrated that the glycosylated form of resveratrol was gradually converted to resveratrol inside the cells. These results indicate that the enzymatic glycosylation of resveratrol could be a useful method for enhancing the bioavailability of resveratrol.

Anticancer Activity of Continentalic Acid in B-Cell Lymphoma

Aralia continentalis has been used in Korea as a folk remedy for arthralgia, rheumatism, and inflammation. However, its anti-lymphoma effect remains uncharacterized. Here, we demonstrate that A. continentalis extract and its three diterpenes efficiently kill B-lymphoma cells. Our in vitro and in vivo results suggest that the cytotoxic activities of continentalic acid, a major diterpene from A. continentalis extract, are specific towards cancer cells while leaving normal murine cells and tissues unharmed. Mechanistically, continentalic acid represses the expression of pro-survival Bcl-2 family members, such as Mcl-1 and Bcl-xL. It dissociates the mitochondrial membrane potential, leading to the stimulation of effector caspase 3/7 activities and, ultimately, cell death. Intriguingly, this agent therapeutically synergizes with roflumilast, a pan-PDE4 inhibitor that has been successfully repurposed for the treatment of aggressive B-cell malignancies in recent clinical tests. Our findings unveiled that A. continentalis extract and three of the plant’s diterpenes exhibit anti-cancer activities. We also demonstrate the synergistic inhibitory effect of continentalic acid on the survival of B-lymphoma cells when combined with roflumilast. Taken in conjunction, continentalic acid may hold significant potential for the treatment of B-cell lymphoma.

Phytochemical Composition, Antioxidant Activity, and Enzyme Inhibitory Activities (α-Glucosidase, Xanthine Oxidase, and Acetylcholinesterase) of Musella lasiocarpa

In this study, we aimed to investigate the chemical components and biological activities of Musella lasiocarpa, a special flower that is edible and has functional properties. The crude methanol extract and its four fractions (petroleum ether, ethyl acetate, n-butanol, and aqueous fractions) were tested for their total antioxidant capacity, followed by their α-glucosidase, acetylcholinesterase, and xanthine oxidase inhibitory activities. Among the samples, the highest total phenolic and total flavonoid contents were found in the ethyl acetate (EtOAc) fraction (224.99 mg GAE/g DE) and crude methanol extract (187.81 mg QE/g DE), respectively. The EtOAc fraction of Musella lasiocarpa exhibited the strongest DPPH· scavenging ability, ABTS·⁺ scavenging ability, and α-glucosidase inhibitory activity with the IC₅₀ values of 22.17, 12.10, and 125.66 μg/mL, respectively. The EtOAc fraction also showed the strongest ferric reducing antioxidant power (1513.89 mg FeSO₄/g DE) and oxygen radical absorbance capacity ability (524.11 mg Trolox/g DE), which were higher than those of the control BHT. In contrast, the aqueous fraction demonstrated the highest acetylcholinesterase inhibitory activity (IC₅₀ = 10.11 μg/mL), and the best xanthine oxidase inhibitory ability (IC₅₀ = 5.23 μg/mL) was observed from the crude methanol extract as compared with allopurinol (24.85 μg/mL). The HPLC-MS/MS and GC-MS analyses further revealed an impressive arsenal of compounds, including phenolic acids, fatty acids, esters, terpenoids, and flavonoids, in the most biologically active EtOAc fraction. Taken together, this is the first report indicating the potential of Musella lasiocarpa as an excellent natural source of antioxidants with possible therapeutic, nutraceutical, and functional food applications.

Tanshinol alleviates ulcerative colitis by promoting the expression of VLDLR

Tanshinol (TAN) is a widely used Chinese medicine ingredient with anti‐inflammatory activity. The therapeutic effect of TAN in ulcerative colitis (UC) deserves further investigation. DSS induced UC model for mice, and TAN of different concentrations was used for in vivo therapy. Colons length was measured; expression of VLDLR in colonic mucosal tissue was evaluated by qRT‐PCR, Western blot and histochemical staining. Besides, normal colorectal mucosal cell line (FHC) was treated with LPS to imitate the inflammatory process of UC in vitro. Different concentrations of TAN treated UC cell model. ELISA and qRT‐PCR were applied to examine the concentrations of inflammatory cytokines (TNF‐α, IL‐6, IL‐8, or IL‐1β). Flow cytometry and MTT was used to identify the apoptosis and viability of FHC cells, respectively. Afterwards, Western blot was performed to detect the expressions of Bax, Bcl‐2, Cleaved caspase‐3, and Cleaved caspase‐9 in FHC cells. VLDLR was low‐expressed in UC tissues as compared to the normal tissue. TAN could alleviate DSS‐induced colons length shortening, colonic tissue structure destruction, inflammatory response, and VLDLR expression decrease in vivo. Further study found that TAN could alleviate LPS‐induced inflammatory response, apoptosis, and viability decrease of FHC cells, and siVLDLR could partially offset the effect of TAN. TAN alleviates LPS‐induced viability decrease, apoptosis, and inflammatory response in FHC cells by promoting VLDLR expression.

Bacillus subtilis Fermentation of Malva verticillata Leaves Enhances Antioxidant Activity and Osteoblast Differentiation

Malva verticillata, also known as Chinese mallow, is an herbaceous plant with colorful flowers and has been used as a medicine for thousands of years. This study investigated this herb for potential antioxidant activity or an association with osteoblast differentiation. M. verticillate leaves were fermented with B. subtilis MV1 at 30 °C for 7 days to enhance their biological activities. The resultant aqueous extract (MVW) and the fermented leaves (MVB) were measured for antioxidant and osteoblast differentiation. The results showed that the total phenolic, flavonoid, and antioxidant activity, as well as the osteoblast differentiation of the MVB increased (2 to 6 times) compared with those of the MVW. MVB induced phosphorylation of p38, extracellular signal-regulated kinase in C3H10T1/2 cells, and the phosphorylation was attenuated via transforming growth factor-β (TGF-β) inhibitors. Moreover, runt-related transcription factor 2 and osterix in the nucleus increased in a time-dependent manner. The messenger RNA expression of alkaline phosphatase and bone sialoprotein increased about 9.4- and 65-fold, respectively, compared to the non-treated cells. MVB stimulated C3H10T1/2 cells in the osteoblasts via TGF-β signaling. Thus, fermented M. verticillata extract exhibited enhanced antioxidant activity and osteoblast differentiation.