Biotransformation of ursolic acid by Syncephalastrum racemosum CGMCC 3.2500 and anti-HCV activity

Microbial transformation of some phytochemicals into value-added products: A review

Phytochemicals, plant-derived compounds, are the major components of traditional medicinal plants. Some phytochemicals have restricted applications, due to low bioavailability and less efficacy. However, their medicinal properties can be enhanced by converting them into value-added products for different bioactivities like anti-oxidant, neuroprotective, anti-obesity, anti-neuroinflammatory, anti-microbial, anti-cancer and anti-inflammatory. Microbial transformation is one such process that is generally more specific and makes it possible to modify a compound without making any unwanted alterations in the molecule. This has led to the efficient production of value-added products with important pharmacological properties and the discovery of new active compounds. The present review assimilates the existing knowledge of the microbial transformation of some phytochemicals like eugenol, curcumin, ursolic acid, cinnamaldehyde, piperine, β-carotene, β-sitosterol, and quercetin to value-added products for their application in food, fragrances, and pharmaceutical industries.

Modification of natural compounds through biotransformation process by microorganisms and their pharmacological properties

The biotransformation of natural compounds by fungal microorganisms is a complex biochemical process. Tandem whole-cell biotransformation offers a promising, alternative, and cost-effective method for modifying of bioactive novel compounds. This approach is particularly beneficial for structurally complex natural products that are difficult to be synthesized through traditional synthetic methods. Biotransformation also provides significant regio- and stereoselectivity, making it a valuable tool for the chemical modification of natural compounds. By utilizing microbial conversion reactions, the biological activity and structural diversity of natural products can be enhanced. In this review, we have summarized 282 novel metabolites resulting from microbial transformation by various microorganisms. We discussed the chemical structures and pharmacological properties of these novel biotransformation products. The review would assist scientists working in the fields of biotechnology, organic chemistry, medicinal chemistry, and pharmacology.

Antimicrobial and Cytotoxic Activities Screening of Marine Invertebrate-Derived Fungi Extract from West Sumatera, Indonesia

BACKGROUND: The coral reef on Mandeh Island, West Sumatra, Indonesia, consists of an abundant source of sponge and soft coral. Secondary metabolites of marine-derived fungi isolated from the sponge and soft coral possess numerous biological activities. AIM: This study collected, identified, and screened marine-derived fungi isolated from marine invertebrates for antibacterial and cytotoxic bioactivities. MATERIALS AND METHODS: The marine invertebrates used are sponges; Xestospongia testudinaria and Placortis communis) and soft corals (Sarcophyton elegan and Subergorgia suberosa). The EtOAc extracts were analyzed for antimicrobial and cytotoxic activities using the diffusion agar method and brine shrimps lethality test. RESULTS: After cultivating on rice medium, the EtOAc extracts of 22 isolated fungi showed potent antimicrobial activity with an inhibitory zone of 15.9 mm against Staphylococcus aureus (XT2 extract), and Pseudomonas aeruginosa of 26.7 mm (XT6 extract), and Candida albicans of 29 mm (SE5 extract). XT6 extract showed the potential cytotoxic activity with an LC50 value of 100 μg/ml. CONCLUSION: The ability of the marine-derived fungi to produce bioactive compounds is promising potential as a source of antimicrobial and cytotoxic compounds.

Biotransformation of ursolic acid by Circinella muscae and their anti-neuroinflammatory activities of metabolites

In this study, the biotransformation of ursolic acid by Circinella muscae CGMCC 3.2695 was investigated. Scaled-up biotransformation reactions yielded ten metabolites. Their structures were established based on extensive NMR and HR-ESI-MS data analyses, and four of them are new compounds. C. muscae could selectively catalyze hydroxylation, lactonisation, carbonylation and carboxyl reduction reactions. Furthermore, all the identified metabolites were evaluated for their anti-neuroinflammatory activities in LPS-induced BV-2 cells. Most metabolites displayed pronounced inhibitory effect on nitric oxide (NO) production. The results suggested that biotransformed derivatives of ursolic acid might be served as potential neuroinflammatory inhibitors.

Biotransformation of Oleanane and Ursane Triterpenic Acids

Oleanane and ursane pentacyclic triterpenoids are secondary metabolites of plants found in various climatic zones and regions. This group of compounds is highly attractive due to their diverse biological properties and possible use as intermediates in the synthesis of new pharmacologically promising substances. By now, their antiviral, anti-inflammatory, antimicrobial, antitumor, and other activities have been confirmed. In the last decade, methods of microbial synthesis of these compounds and their further biotransformation using microorganisms are gaining much popularity. The present review provides clear evidence that industrial microbiology can be a promising way to obtain valuable pharmacologically active compounds in environmentally friendly conditions without processing huge amounts of plant biomass and using hazardous and expensive chemicals. This review summarizes data on distribution, microbial synthesis, and biological activities of native oleanane and ursane triterpenoids. Much emphasis is put on the processes of microbial transformation of selected oleanane and ursane pentacyclic triterpenoids and on the bioactivity assessment of the obtained derivatives.

Antiviral Evaluation of Herbal Drugs

The viral infection and resistance to the existing antiviral drugs are alarming, which is a serious public health concern. Medicinal plants are valuable resources for treatment of viral infections and can be used for the management of infections like herpes simplex virus (HSV), human immunodeficiency virus (HIV), influenza, etc. The antiviral screening of plant extracts should be highly selective, specific, and sensitive for bioactivity guided isolation of the active compounds from the plant extracts. The antiviral screening system should be validated for accuracy, reproducibility, simplicity, and cost effectiveness. This chapter highlights on various aspects for screening and evaluation of antiviral natural components including factors affecting antiviral in vivo studies, host cells, organisms, and culture media followed by different virus-specific assays for antiviral screening of natural products.

Microbe-mediate transformation of echinocystic acid by whole cells of filamentous fungus Cunninghamella blakesleana CGMCC 3.910

Structural modification of echinocystic acid (EA), a pentacyclic triterpenoid with wide spread biological activities was investigated by microbial transformation. Microbe-mediate transformation of EA was carried out by filamentous fungus Cunninghamella blakesleana CGMCC 3.910. Four metabolites 3β, 7β, 16α-trihydroxy-olean-12-en-28-oic acid (EA-2); 3β, 7β, 16β,19β-tetrahydroxy-olean-12-en-28-oic acid (EA-3); 3β, 7β, 16α, 21β-tetrahydroxy-olean-12-en-28-oic acid (EA-4); 3β, 7β, 16α-trihydroxy-olean-11, 13(18)-dien-28-oic acid (EA-5) were produced. Structures of transformed products were elucidated by 1D and 2D NMR and HR-MS data. EA-3 and EA-4 were new compounds.

Two new triterpenoids from the roots of Phyllanthus emblica

Two new triterpenes, the seco-friedelane type secofriedelanophyllemblicine and the ursane-derived saponin ursophyllemblicoside were isolated from the roots of the edible fruit-producing Phyllanthus emblica. Their structures were unambiguously elucidated using extensive 1D and 2D NMR analyses, high resolution mass spectrometry and single-crystal X-ray crystallographic analyses along with comparison with literature data. Secofriedelanophyllemblicine represents the first 3,4-secofriedelane bearing a carboxylic acid group substituent at C-20. Ursophyllemblicoside, incorporating the rare 21α hydroxyursolic acid as a sapogenol represents the first example of saponin comprising this aglycone. Secofriedelanophyllemblicine displayed a moderate cytotoxicity against K562 and HepG2 cancer cell lines.

Application of α- and β-naphthoflavones as monooxygenase inhibitors of Absidia coerulea KCh 93, Syncephalastrum racemosum KCh 105 and Chaetomium sp. KCh 6651 in transformation of 17α-methyltestosterone

In this work, 17α-methyltestosterone was effectively hydroxylated by Absidia coerulea KCh 93, Syncephalastrum racemosum KCh 105 and Chaetomium sp. KCh 6651. A. coerulea KCh 93 afforded 6β-, 12β-, 7α-, 11α-, 15α-hydroxy derivatives with 44%, 29%, 6%, 5% and 9% yields, respectively. S. racemosum KCh 105 afforded 7α-, 15α- and 11α-hydroxy derivatives with yields of 45%, 19% and 17%, respectively. Chaetomium sp. KCh 6651 afforded 15α-, 11α-, 7α-, 6β-, 9α-, 14α-hydroxy and 6β,14α-dihydroxy derivatives with yields of 31%, 20%, 16%, 7%, 5%, 7% and 4%, respectively. 14α-Hydroxy and 6β,14α-dihydroxy derivatives were determined as new compounds. Effect of various sources of nitrogen and carbon in the media on biotransformations were tested, however did not affect the degree of substrate conversion or the composition of the products formed. The addition of α- or β-naphthoflavones inhibited 17α-methyltestosterone hydroxylation but did not change the percentage composition of the resulting products.

Biotransformation of ursolic acid by Alternaria longipes AS3.2875

Microbial transformation of ursolic acid (1) was carried out by Alternaria longipes AS 3.2875. Six transformed products (2-7) from 1 were isolated and their structures were identified as 3-carbonyl ursolic acid 28-O-β-D-glucopyranosyl ester (2), ursolic acid 3-O-β-D-glucopyranoside (3), ursolic acid 28-O-β-D-glucopyranosyl ester (4), 2α, 3β-dihydroxy ursolic acid 28-O-β-D-glucopyranosyl ester (5), 3β, 21β dihydroxy ursolic acid 28-O-β-D-glucopyranosyl ester (6), and 3-O-(β-D-glucopyranosyl)- ursolic acid 28-O-(β-D-glucopyranosyl) ester (7) based on the analysis of 1D NMR, 2DNMR and MS data. The product 2 was a new compound among them and showed stronger antibacterial activity against S. aureu, MRSA and MRCA than substrate. In this study, we modified structure of ursolic acid through biotransformation to enhance its activities and preliminarily discussed the transformation way of the products.

Biocatalysis of ursolic acid by the fungus Gliocladium roseum CGMCC 3.3657 and resulting anti-HCV activity

Biocatalysis of ursolic acid (UA 1) by Gliocladium roseum CGMCC 3.3657 was investigated.

New derivatives of ursolic acid through the biotransformation by Bacillus megaterium CGMCC 1.1741 as inhibitors on nitric oxide production

Microbial transformation of ursolic acid (1) by Bacillus megaterium CGMCC 1.1741 was investigated and yielded five metabolites identified as 3-oxo-urs-12-en-28-oic acid (2); 1β,11α-dihydroxy-3-oxo-urs-12-en-28-oic acid (3); 1β-hydroxy-3-oxo-urs-12-en-28, 13-lactoe (4); 1β,3β, 11α-trihydroxyurs-12-en-28-oic acid (5) and 1β,11α-dihydroxy-3-oxo-urs-12-en-28-O-β-d-glucopyranoside (6). Metabolites 3, 4, 5 and 6 were new natural products. Their nitric oxide (NO) production inhibitory activity was assessed in lipopolysaccharide (LPS) - stimulated RAW 264.7 cells. Compounds 3 and 4 exhibited significant activities with the IC50 values of 1.243 and 1.711μM, respectively. A primary structure-activity relationship was also discussed.

Anti-hepatocellular carcinoma activity and mechanism of chemopreventive compounds: ursolic acid derivatives

CONTEXT

Hepatocellular carcinoma (HCC) is a common cancer around the world, with high mortality rate. Currently, there is no effective drug for the therapy of HCC. Ursolic acid (UA) is a natural product which exists in various medicinal herbs and fruits, exhibiting multiple biological effects such as its outstanding anticancer and hepatoprotective activity, which has drawn many pharmacists' attention.

OBJECTIVE

This paper summarizes the current status of the hepatoprotective activity of UA analogues and explains the related mechanism, providing a clear direction for the development of novel anti-HCC drugs.

METHODS

All of the data resources were derived from PubMed. By comparing the IC50 values and analyzing the structure-activity relationships, we listed compounds with good pharmacological activity from the relevant literature, and summarized their anti-HCC mechanism.

RESULTS

From the database, 58 new UA derivatives possessing wonderful anticancer and hepatoprotective effects were listed, and the relevant anti-HCC mechanism were discussed.

CONCLUSION

UA's anti-HCC effect is the result of combined action of many mechanisms. These 58 new UA derivatives, particularly compounds 45 and 53, can be used as potential drugs for the treatment of liver cancer.

Structural analysis of metabolites of asiatic acid and its analogue madecassic acid in zebrafish using LC/IT-MSn

Although zebrafish has become a significant animal model for drug discovery and screening, drug metabolism in zebrafish remains largely unknown. Asiatic acid (AA) and madecassic acid (MA), two natural pentacyclic triterpenoids mainly obtained from Centella asiatica (L.) Urban, have been found to possess many pharmacological effects. This study is to probe the metabolic capability of zebrafish via investigation of the drug metabolism of AA and MA in zebrafish, using a sensitive LC/IT-MSn method. In addition, the main fragmentation pathways of AA and MA were reported for the first time. Nineteen metabolites of AA and MA were firstly identified after zebrafish was exposed to the drug, which all were the phase I metabolites and mainly formed from hydroxylation, dehydrogenation, hydroxylation and dehydrogenation, dihydroxylation and dehydrogenation, and dehydroxylation reaction. The results indicated that zebrafish possessed strong metabolic capacity, and the metabolites of AA and MA were formed via similar metabolic pathways and well matched with the known metabolic rules in vivo and in vitro, which supports the widely use of this system in drug metabolism research. This investigation would also contribute to the novel information on the structural elucidation, in vivo metabolites and metabolic mechanism of pentacyclic triterpenoids.

Validation of Antiviral Potential of Herbal Ethnomedicine

Natural products are the basis of treatment since the dawn of human civilization, and modern medicine has gradually developed, over the years, by scientific and observational efforts from traditional medicine. Today most of the synthetic drugs showed adverse and unacceptable side effects, however, impressive bioactivities with reduced toxicities were reported for many botanicals against several chronic or difficult-to-treat diseases. A whole range of viral diseases including human immunodeficiency virus/acquired immunodeficiency syndrome, severe acute respiratory syndrome, Rabies, Dengue, and Herpes need effective drugs. Considerable research has been carried out on the pharmacognosy, chemistry, pharmacology, and therapeutics of traditional medicines of diverse cultures, and many pharmaceutical companies have renewed their strategies for antiviral drug development where no effective drugs or vaccine exist. Thus, phytochemicals with antiviral potentials need to be studied in depth with standardization, chemical isolation, effectivity, molecular mechanism, along with in vivo toxicity and efficacy to reduce cost and time. This review will portray the scientific approaches and methodologies used for the development of antiviral leads from traditional medicines against selected genetically and functionally diverse viral infections.

Microbial-catalyzed biotransformation of multifunctional triterpenoids derived from phytonutrients

Microbial-catalyzed biotransformations have considerable potential for the generation of an enormous variety of structurally diversified organic compounds, especially natural products with complex structures like triterpenoids. They offer efficient and economical ways to produce semi-synthetic analogues and novel lead molecules. Microorganisms such as bacteria and fungi could catalyze chemo-, regio- and stereospecific hydroxylations of diverse triterpenoid substrates that are extremely difficult to produce by chemical routes. During recent years, considerable research has been performed on the microbial transformation of bioactive triterpenoids, in order to obtain biologically active molecules with diverse structures features. This article reviews the microbial modifications of tetranortriterpenoids, tetracyclic triterpenoids and pentacyclic triterpenoids.