Purification of a novel ribonuclease from dried fruiting bodies of the edible wild mushroom Thelephora ganbajun

Anticancer potentiality and mode of action of low-carbohydrate proteins and peptides from mushrooms

Severe side effects of chemotherapy as well as drug resistance highlight the ongoing need to discover novel natural bioactive compounds with anticancer potentiality. Mushroom-derived proteins are among the naturally occurring compounds that have been the subject of a body of research on their potentiality in cancer therapy. The greatest attention in relevant review articles has been paid to well-known mushroom-derived glycoproteins such as lectins and protein-bound polysaccharide complexes such as polysaccharide-K (PSK) or krestin and polysaccharopeptide (PSP), which contain substantial amounts of carbohydrates (50-90%). These complex compounds exert their anticancer activity mainly by binding to cell membranes leading to extrinsic (death receptor) apoptosis or intrinsic (mitochondrial) apoptotic pathways. However, several other research studies have reported pure, well-characterized, proteins or peptides from mushrooms, which are carbohydrate-free or have very low amounts of carbohydrate. These proteins may fall into four categories including fungal immunomodulatory proteins, ubiquitin-like proteins, enzymes, and unclassified proteins. Well-defined chemical structure, elucidated full amino acid or N-terminal sequences, purity, and having some distinct and specific pathways compared to glycoproteins have made these low-carbohydrate proteins attractive for cancer research. The aim of this review was therefore to improve the current understanding of mushroom-derived low-carbohydrate proteins and to consolidate the existing knowledge of the most promising mushroom species from which low-carbohydrate proteins have been derived, characterized, and examined for their anticancer activity. In addition, molecular targets and mechanisms of action of these proteins have been discussed. Key points • Mushroom-derived low-carbohydrate proteins lack or have low carbohydrate. • Low-carbohydrate proteins show potent anticancer activities in vitro and in vivo. • There are specific pathways for low-carbohydrate proteins to inhibit cancer cells.

Bioactive Phytochemical Constituents of Wild Edible Mushrooms from Southeast Asia

Mushrooms have a long history of uses for their medicinal and nutritional properties. They have been consumed by people for thousands of years. Edible mushrooms are collected in the wild or cultivated worldwide. Recently, mushroom extracts and their secondary metabolites have acquired considerable attention due to their biological effects, which include antioxidant, antimicrobial, anti-cancer, anti-inflammatory, anti-obesity, and immunomodulatory activities. Thus, in addition to phytochemists, nutritionists and consumers are now deeply interested in the phytochemical constituents of mushrooms, which provide beneficial effects to humans in terms of health promotion and reduction of disease-related risks. In recent years, scientific reports on the nutritional, phytochemical and pharmacological properties of mushroom have been overwhelming. However, the bioactive compounds and biological properties of wild edible mushrooms growing in Southeast Asian countries have been rarely described. In this review, the bioactive compounds isolated from 25 selected wild edible mushrooms growing in Southeast Asia have been reviewed, together with their biological activities. Phytoconstituents with antioxidant and antimicrobial activities have been highlighted. Several evidences indicate that mushrooms are good sources for natural antioxidants and antimicrobial agents.

Simultaneous quantification of free amino acids and 5'-nucleotides in shiitake mushrooms by stable isotope labeling-LC-MS/MS analysis

Evaluation of free amino acids (FAAs) and nucleotides in various food matrices has been a widely studied topic in recent years. Here, a fast and efficient strategy for the simultaneous analysis of 20 FAAs and six 5'-nucleotides, using stable isotope labeling-liquid chromatography coupled with tandem mass spectrometry (SIL-LC-MS/MS) is proposed. The method was validated with respect to selectivity, linearity, limits of detection (LOD) and quantification (LOQ), recovery, precision, and stability. LOQs of most FFAs were lower than 1 ng/mL, and 5'-nucleotides were in the range of 5-20 ng/mL. FAAs and 5'-nucleotides in ten shiitake mushrooms from different cultivate areas were further analyzed. Results showed that the contents of cytidine 5'-monophosphate, adenosine 5'-monophosphate, lysine, threonine, arginine were significantly different. Principal component analysis showed clear discrimination of origins, seasons and species. Thus, the proposed method is suitable for the fast discrimination of species and geographical origins of shiitake mushrooms.

A Ribonuclease Isolated from Wild Ganoderma Lucidum Suppressed Autophagy and Triggered Apoptosis in Colorectal Cancer Cells

The mushroom Ganoderma lucidum (G. lucidum) has been consumed in China as a medicine for promoting health and longevity for thousands of years. Due to its paramount and multiple pharmaceutical effects, G. lucidum has received considerable attention from researchers and its chemical constituents as well as their respective functions were gradually unveiled by using modern research methods. Herein, we reported the isolation of a protein (Ganoderma lucidum ribonuclease, GLR) with anti-colorectal cancer activities from G. lucidum. This protein is a 17.4-kDa RNA degrading enzyme (ribonuclease) and was purified by using liquid chromatography procedures. GLR manifested potent anti-proliferative and anti-colony formation activities on HT29 and HCT116 colorectal cancer cells by inducing cell cycle arrest in G1 phase through the regulation of cyclin D1 and P53 expression. GLR was demonstrated to induce cell apoptosis in HCT116 cells by activating unfolded protein response and caspase-9 regulated pathways. Besides, the ability to undergo autophagy which is a stress adaption mechanism to cope with metabolic crisis was significantly suppressed by GLR treatment in HCT116 cells. The activation of apoptosis in GLR-treated HT29 cells was, however, independent of caspase-9 and the suppression of autophagy was also relatively minor. Thus the apoptosis of HT29 cells triggered by GLR was much milder than that in HCT116 cells. Our findings show that the RNase from G. lucidum may be one of the bioactive components that contribute to the anti-colorectal cancer activity of G. lucidum.

Purification and characterization of a ribonuclease with antiproliferative activity from the mystical wild mushroom Tuber indicum

An RNase with a molecular mass of 28 kDa and with high ribonucleolytic activity toward poly(A) was purified from the ascocarps of Tuber indicum. The purification procedure involved ion exchange chromatography on diethylaminoethyl cellulose, Q-Sepharose and Mono Q, and gel filtration by fast protein liquid chromatography on Superdex 75. The pH and temperature optima of the RNase were 7.2 and 50 °C, respectively. The ranking of its activity toward various polyhomoribonucleotides was poly(A)>poly(C)>poly(G) ≈ poly(U). All of the metal ions used in this study, except for the K(+) ions, curtailed the activity of the RNase. The RNase activity was reduced by ethylene diamine tetraacetic acid (EDTA), dithiothreitol (DTT), and sodium dodecyl sulfate (SDS) by 42.2%, 75.5%, and 96.6%, respectively. The RNase inhibited the proliferation of hepatoma (HepG2) and human breast cancer cell lines (MCF7), with half-maximal inhibitory concentrations (IC50 ) of 12.6 and 16.6 μM, respectively.

First biochemical characterization of a novel ribonuclease from wild mushroom Amanita hemibapha

A 45-kDa ribonuclease (RNase) was purified from dried fruiting bodies of the wild mushroom Amanita hemibapha. It was adsorbed on DEAE-cellulose, S-sepharose, and finally purified on Superdex 75. The RNase exhibited maximal RNase activity at pH 5 and in a temperature range between 60-70°C. It demonstrated no ribonucleolytic activity toward four polyhomoribonucleotides. The amino acid sequence analysis (GDDETFWEHEWAK) showed this RNase was a ribonuclease T2-like RNase. It exhibited strong inhibitory activity against HIV-1 reverse transcriptase (HIV-1 RT) with an IC₅₀ of 17 μM.

A novel ribonuclease with potent HIV-1 reverse transcriptase inhibitory activity from cultured mushroom Schizophyllum commune

A 20-kDa ribonuclease (RNase) was purified from fresh fruiting bodies of cultured Schizophyllum commune mushrooms. The RNase was not adsorbed on Affi-gel blue gel but adsorbed on DEAE-cellulose and CM-cellulose. It exhibited maximal RNase activity at pH 6.0 and 70°C. It demonstrated the highest ribonucleolytic activity toward poly (U) (379.5 μ/mg), the second highest activity toward poly (C) (244.7 μ/mg), less activity toward poly (A) (167.4 μ/mg), and much weaker activity toward poly (G) (114.5 μ/mg). The RNase inhibited HIV-1 reverse transcriptase with an IC(50) of 65 μM. No effect on [(3)H-methyl]-thymidine uptake by lymphoma MBL2 cells and leukemia L1210 cells was observed at 100 μM concentration of the RNase. A comparison of RNases from S. commune and Volvariella volvacea revealed that they demonstrated some similarities in N-terminal amino acid sequence, optimum pH and polyhomoribonucleotide specificity. However, some differences in chromatographic behavior and molecular mass were observed.

Ribonucleases of different origins with a wide spectrum of medicinal applications

Ribonucleases (RNases) are a type of nucleases that catalyze the degradation of RNA into smaller components. They exist in a wide range of life forms from prokaryotes to eukaryotes. RNase-controlled RNA degradation is a determining factor in the control of gene expression, maturation and turnover, which are further associated with the progression of cancers and infectious diseases. Over the years, RNases purified from multiple origins have drawn increasing attention from medical scientists due to their remarkable antitumor properties. In this review, we present a brief summary of the representative RNases of fungal, bacterial, plant, and animal origins and outline their potential medicinal value in the treatment of tumor and AIDS. Among them, the most clinically promising RNases are mushroom RNases, Binase and Barnase from bacteria, ginseng RNases, and Onconase from frog (Rana pipiens). Fast developing protein engineering of RNases, which display more potent cytotoxic activity on and greater selectivity for malignant cells, has also aroused the interest of researchers. The multiple anti-cancer mechanisms of RNases are also included. To sum up, these inspiring studies unveil a new perspective for RNases as potential therapeutic agents.

A protein with antiproliferative, antifungal and HIV-1 reverse transcriptase inhibitory activities from caper (Capparis spinosa) seeds

A protein exhibiting an N-terminal amino acid sequence with some similarity to imidazoleglycerol phosphate synthase was purified from fresh Capparis spinosa melon seeds. The purification protocol entailed anion exchange chromatography on DEAE-cellulose, cation exchange chromatography on SP-Sepharose, and finally gel filtration by fast protein liquid chromatography on Superdex 75. The protein was adsorbed using 20 mM Tris-HCl buffer (pH 7.4) and desorbed using 1 M NaCl in the starting buffer from the DEAE-cellulose column and SP-Sepharose column. The protein demonstrated a molecular mass of 38 kDa in gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, indicating that it was monomeric. The protein inhibited proliferation of hepatoma HepG2 cells, colon cancer HT29 cells and breast cancer MCF-7 cells with an IC(50) of about 1, 40 and 60 microM, respectively. It inhibited HIV-1 reverse transcriptase with IC(50) of 0.23 microM. It inhibited mycelial growth in the fungus, Valsa mali. It did not exhibit hemagglutinating, ribonuclease, mitogenic or protease inhibitory activities.

A novel ribonuclease from fresh fruiting bodies of the portabella mushroom Agaricus bisporus

A 14 kDa ribonuclease with a novel N-terminal sequence was isolated from fresh fruiting bodies of the portabella mushroom. It was adsorbed on DEAE-cellulose and carboxymethyl-cellulose, and demonstrated the highest ribonucleolytic potency toward poly (A), 60% as much activity toward poly (C), 40% as much activity toward poly (U), and the least activity (7% as much) toward poly (G). It exhibited a pH optimum at pH 4.5 and a temperature optimum at 60 °C. Its activity at 100 °C was higher than that at 20 °C.Key words: ribonuclease, portabella mushroom, isolation.