Microbial transformation of deoxyandrographolide and their inhibitory activity on LPS-induced NO production in RAW 264.7 macrophages

Biotransformation of selected secondary metabolites by Alternaria species and the pharmaceutical, food and agricultural application of biotransformation products

Biotransformation is a process in which molecules are modified in the presence of a biocatalyst or enzymes, as well as the metabolic alterations that occur in organisms from exposure to the molecules. Microbial biotransformation is an important process in natural product drug discovery as novel compounds are biosynthesised. Additionally, biotransformation products offer compounds with improved efficacy, solubility, reduced cytotoxic and allows for the understanding of structure activity relationships. One of the driving forces for these impeccable findings are associated with the presence of cytochrome P450 monooxygenases that is present in all organisms such as mammals, bacteria, and fungi. Numerous fungal strains have been used and reported for their ability to biotransform different compounds. This review focused on studies using Alternaria species as biocatalysts in the biotransformation of natural product compounds. Alternaria species facilitates reactions that favour stereoselectivity, regioselectivity under mild conditions. Additionally, microbial biotransformation products, their application in food, pharmaceutical and agricultural sector is discussed in this review.

An Overview of Biotransformation and Toxicity of Diterpenes

Diterpenes have been identified as active compounds in several medicinal plants showing remarkable biological activities, and some isolated diterpenes are produced at commercial scale to be used as medicines, food additives, in the synthesis of fragrances, or in agriculture. There is great interest in developing methods to obtain derivatives of these compounds, and biotransformation processes are interesting tools for the structural modification of natural products with complex chemical structures. Biotransformation processes also have a crucial role in drug development and/or optimization. The understanding of the metabolic pathways for both phase I and II biotransformation of new drug candidates is mandatory for toxicity and efficacy evaluation and part of preclinical studies. This review presents an overview of biotransformation processes of diterpenes carried out by microorganisms, plant cell cultures, animal and human liver microsomes, and rats, chickens, and swine in vivo and highlights the main enzymatic reactions involved in these processes and the role of diterpenes that may be effectively exploited by other fields.

Biotransformation of neuro-inflammation inhibitor kellerin using Angelica sinensis (Oliv.) Diels callus

This paper mainly focused on biotransformation of coumarins using Angelica sinensis (Oliv.) Diels callus.

Regioselective glucuronidation of andrographolide and its major derivatives: metabolite identification, isozyme contribution, and species differences

Andrographolide (AND) and two of its derivatives, deoxyandrographolide (DEO) and dehydroandrographolide (DEH), are widely used in clinical practice as anti-inflammatory agents. However, UDP-glucuronosyltransferase (UGT)-mediated phase II metabolism of these compounds is not fully understood. In this study, glucuronidation of AND, DEO, and DEH was characterized using liver microsomes and recombinant UGT enzymes. We isolated six glucuronides and identified them using 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. We also systematically analyzed various kinetic parameters (K m, V max, and CLint) for glucuronidation of AND, DEO, and DEH. Among 12 commercially available UGT enzymes, UGT1A3, 1A4, 2B4, and 2B7 exhibited metabolic activities toward AND, DEO, and DEH. Further, UGT2B7 made the greatest contribution to glucuronidation of all three anti-inflammatory agents. Regioselective glucuronidation showed considerable species differences. 19-O-Glucuronides were present in liver microsomes from all species except rats. 3-O-Glucuronides were produced by pig and cynomolgus monkey liver microsomes for all compounds, and 3-O-glucuronide of DEH was detected in mouse and rat liver microsomes (RLM). Variations in K m values were 48.6-fold (1.93-93.6 μM) and 49.5-fold (2.01-99.1 μM) for 19-O-glucuronide and 3-O-glucuronide formation, respectively. Total intrinsic clearances (CLint) for 3-O- and 19-O-glucuronidation varied 4.8-fold (22.7-110 μL min(-1) mg(-1)), 10.6-fold (94.2-991 μL min(-1) mg(-1)), and 8.3-fold (122-1,010 μL min(-1) mg(-1)), for AND, DEH, and DEO, respectively. Our results indicate that UGT2B7 is the major UGT enzyme involved in the metabolism of AND, DEO, and DEH. Metabolic pathways in the glucuronidation of AND, DEO, and DEH showed considerable species differences.

Biotransformation of 11-keto-β-boswellic acid by Cunninghamella blakesleana

11-Keto-β-boswellic acid (KBA), as one of the active constituents in the gum resin of Boswellia serrata, possesses significant biological activities including anti-inflammatory activity. However, its extensive metabolism and low polarity has limited the systemic availability of KBA. The present research was aimed to obtain and explore the various possible derivatives of KBA through biotransformation by Cunninghamella blakesleana AS 3.970. A total of ten transformed compounds were isolated and purified, and their chemical structures were characterized as 7β-hydroxy-11-keto-β-boswellic acid; 7β, 15α-dihydroxy-11-keto-β-boswellic acid ; 7β, 16β-dihydroxy-11-keto-β-boswellic acid; 7β, 16α-dihydroxy-11-keto-β-boswellic acid; 7β, 22β-dihydroxy-11-keto-β-boswellic acid; 7β, 21β-dihydroxy-11-keto-β-boswellic acid; 7β, 20β-dihydroxy-11-keto-β-boswellic acid; 7β, 30-dihydroxy-11-keto-β-boswellic acid; 3α, 7β-dihydroxy-11-oxours-12-ene-24, 30-dioic acid and 3α, 7β-dihydroxy-30-(2-hydroxypropanoyloxy)-11-oxours-12-en-24-oic acid by various spectroscopic methods. The biotransformation processes include hydroxylation, oxidation and esterification. Primary structure-activity relationships (SAR) of inhibitory effects on NO production in RAW 264.7 macrophage cells are discussed.

Microbial transformation of acetyl-11-keto-boswellic acid by Cunninghamella elegans

Microbial biotransformation of acetyl-11-keto-boswellic acid by Cunninghamella elegans AS 3.1207 was carried out, and totally four transformed products were isolated. On the basis of the extensive spectral data, their structures were characterized as 7β-hydroxy-11-keto-boswellic acid (1), 7β,30-dihydroxy-11-keto-boswellic acid (2), 7β,16α-dihydroxy-3-acetyl-11-keto-boswellic acid (3), and 7β,15α,21β-trihydroxy-3-acetyl-11-keto-boswellic acid (4), respectively. Among them, products 1 and 2 are the new compounds.

Biotransformation of osthole by Alternaria longipes

The biotransformation of osthole (1) by Alternaria longipes was carried out, and five transformed products were obtained in the present research work. Based on their extensive spectral data, the structures of these metabolites were characterized as 4'-hydroxyl-osthole (2), 4'-hydroxyl-2',3'-dihydroosthole (3), 2',3'-dihydroxylosthole (4), osthole-4'-oic acid methyl ester (5), and osthole-4'-oic acid glucuron-1-yl ester (6), respectively. Among them, products 5 and 6 were new compounds.

Novel microbial transformation of desacetylcinobufagin by Fusarium avenaceum AS 3.4594

In this paper, the microbial transformation of desacetylcinobufagin (1) by Fusarium avenaceum AS 3.4594 was investigated, and four metabolites were isolated and characterized as 3-keton-desacetylcinobufagin (2), 3-epi-desacetylcinobufagin (3), bufadienolide A (4), and 15β,16α-dihydroxyl-17βH-bufalin (5), respectively. Among them, 4 and 5 are new compounds. The cytotoxicities of transformed products (2-5) against Hela cells were also investigated.

Microbial biotransformation of kurarinone by Cunninghamella echinulata AS 3.3400

In this paper, microbial transformation of kurarinone (1) by Cunninghamella echinulata AS 3.3400 was investigated and four transformed products were isolated and identified as 6″-hydroxykurarinone (2), 4″,5″,8″-trihydroxynorkurarinone (3), norkurarinone (4), and kurarinone-7-O-β-glucoside (5), respectively. Among them, 3 and 5 are new compounds, and the rare glycosylation in microbial transformation was observed. In addition, the cytotoxicities of transformed products (2-5) were also investigated.

Microbial transformation of Norkurarinone by Cunninghamella blakesleana AS 3.970

In this paper, microbial transformation of norkurarinone (1) by Cunninghamella blakesleana AS 3.970 was investigated and seven transformed products were isolated and characterized as kurarinone (2), 4″,5″-dihydroxykurarinone (3), 6″-hydroxyl-2'-methoxyl-norkurarinone 7-O-β-d-glucoside (4), 6″-hydroxyl-norkurarinone 4'-O-β-d-glucoside (5), 4″,5″-dihydroxynorkurarinone (6), 7-methoxyl-norkurarinone (7), and 7-methoxyl-4″,5″-dihydroxynorkurarinone (8), respectively. Among them, 3-5 are new compounds, and the glycosylation reaction in microbial transformation process was reported rarely. In addition, the cytotoxicities of transformed products (1-8) were also investigated.