Flavonoids are nearly ubiquitous in plants and are recognized as the pigments responsible for the colors of leaves, especially in autumn. They are rich in seeds, citrus fruits, olive oil, tea, and red wine. They are low molecular weight compounds composed of a three-ring structure with various substitutions. This basic structure is shared by tocopherols (vitamin E). Flavonoids can be subdivided according to the presence of an oxy group at position 4, a double bond between carbon atoms 2 and 3, or a hydroxyl group in position 3 of the C (middle) ring. These characteristics appear to also be required for best activity, especially antioxidant and antiproliferative, in the systems studied. The particular hydroxylation pattern of the B ring of the flavonoles increases their activities, especially in inhibition of mast cell secretion. Certain plants and spices containing flavonoids have been used for thousands of years in traditional Eastern medicine. In spite of the voluminous literature available, however, Western medicine has not yet used flavonoids therapeutically, even though their safety record is exceptional. Suggestions are made where such possibilities may be worth pursuing.

The Effects of Plant Flavonoids on Mammalian Cells:Implications for Inflammation, Heart Disease, and Cancer

https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Proteases represent the class of enzymes which occupy a pivotal position with respect to their physiological roles as well as their commercial applications. They perform both degradative and synthetic functions. Since they are physiologically necessary for living organisms, proteases occur ubiquitously in a wide diversity of sources such as plants, animals, and microorganisms. Microbes are an attractive source of proteases owing to the limited space required for their cultivation and their ready susceptibility to genetic manipulation. Proteases are divided into exo- and endopeptidases based on their action at or away from the termini, respectively. They are also classified as serine proteases, aspartic proteases, cysteine proteases, and metalloproteases depending on the nature of the functional group at the active site. Proteases play a critical role in many physiological and pathophysiological processes. Based on their classification, four different types of catalytic mechanisms are operative. Proteases find extensive applications in the food and dairy industries. Alkaline proteases hold a great potential for application in the detergent and leather industries due to the increasing trend to develop environmentally friendly technologies. There is a renaissance of interest in using proteolytic enzymes as targets for developing therapeutic agents. Protease genes from several bacteria, fungi, and viruses have been cloned and sequenced with the prime aims of (i) overproduction of the enzyme by gene amplification, (ii) delineation of the role of the enzyme in pathogenecity, and (iii) alteration in enzyme properties to suit its commercial application. Protein engineering techniques have been exploited to obtain proteases which show unique specificity and/or enhanced stability at high temperature or pH or in the presence of detergents and to understand the structure-function relationships of the enzyme. Protein sequences of acidic, alkaline, and neutral proteases from diverse origins have been analyzed with the aim of studying their evolutionary relationships. Despite the extensive research on several aspects of proteases, there is a paucity of knowledge about the roles that govern the diverse specificity of these enzymes. Deciphering these secrets would enable us to exploit proteases for their applications in biotechnology.

Molecular and Biotechnological Aspects of Microbial Proteases

https://www.cell.com/cell/pdf/0092-8674(94)90570-3.pdf

RAFT1: a mammalian protein that binds to FKBP12 in a rapamycin-dependent fashion and is homologous to yeast TORs.

The influence of natural products upon drug discovery.

The immuno-pharmacological profile of a novel immunosuppressive agent, FK-506 produced by a streptomycete, is presented here. We proceeded to test the effect of the agent on various in vitro immune systems. It showed that mixed lymphocyte reaction, cytotoxic T cell generation, the production of T cell-derived soluble mediators such as interleukin 2 (IL-2), interleukin 3 and gamma-interferon and the expression of the IL-2 receptor were suppressed by this agent. The IC50 values of FK-506 and ciclosporin (CS) in all tests were approximately 0.1nM and 10nM, respectively. Therefore, the novel agent, FK-506 suppressed in vitro immune systems at about hundred times lower concentration than CS.

https://www.jstage.jst.go.jp/article/antibiotics1968/40/9/40_9_1249/_pdf

FK-506, a novel immunosuppressant isolated from a Streptomyces. II. Immunosuppressive effect of FK-506 in vitro.

FK-506, a novel immunosuppressant, has been isolated from the fermentation broth of Streptomyces tsukubaenis No. 9993 as colorless prism and the molecular formula was determined as C44H69NO12.H2O. The compound suppressed immune responses in vitro and in vivo with mice. This immunosuppressive effect was more potent than that of ciclosporin.

FK-506, a novel immunosuppressant isolated from a Streptomyces. I. Fermentation, isolation, and physico-chemical and biological characteristics.

Nocardicin A is a new monocyclic beta-lactam antibiotic obtained from the fermentation broth of a strain of actinomycetes. The producing organism, strain WS 1571, was identified as Nocardia uniformis subsp. tsuyamanensis ATCC 21806. The antibiotic, obtained as colorless crystals, exhibits moderate in vitro antibacterial activity against a broad-spectrum of Gram-negative bacteria including Proteus and Pseudomonas. It has low toxicity in laboratory animals.

NOCARDICIN A, A NEW MONOCYCLIC β-LACTAM ANTIBIOTIC

Swainsonine isolated from Metarhizium sp., was found to enhance the activities of the mouse immune system in vitro. Concanavalin A stimulated lymphocyte proliferation and proliferative response in mixed lymphocytes culture, which were suppressed by immunosuppressive factor obtained from serum of sarcoma 180 tumor bearing mouse, were restored to normal levels by the addition of swainsonine. Furthermore, the concanavalin A induced incorporation of [3H] thymidine into mouse spleen cells was remarkably increased by treatment with swainsonine over a wide dose range. From studies using fluorescence activated cell sorting, swainsonine was shown to enhance the expression of concanavalin A receptors of spleen cells.

Studies of an immunomodulator, swainsonine. I. Enhancement of immune response by swainsonine in vitro.

Lavendomycin, a new basic peptide antibiotic containing novel amino acids, has been isolated from the culture broth of a streptomyces designated as Streptomyces lavendulae subsp. brasilicus. The antibiotic obtained as colorless crystals (C29H50N10O8, MW 666) is active against Gram-positive bacteria in vitro and in vivo, however, inactive against Gram-negative bacteria and fungi. An acute toxicity of the antibiotic in mice was LD50 greater than 2 g/kg by subcutaneous injection.

Masanobu Kohsaka

Papers

FK-506, a novel immunosuppressant isolated from a Streptomyces. II. Immunosuppressive effect of FK-506 in vitro.

FK-506, a novel immunosuppressant isolated from a Streptomyces. I. Fermentation, isolation, and physico-chemical and biological characteristics.

NOCARDICIN A, A NEW MONOCYCLIC β-LACTAM ANTIBIOTIC

Studies of an immunomodulator, swainsonine. I. Enhancement of immune response by swainsonine in vitro.

Bicyclomycin, a new antibiotic. I. Taxonomy, isolation and characterization.