# Naturally Occurring Flavonoids and Isoflavonoids and Their Microbial Transformation: A Review
## 2 Isoflavonoids and Flavonoids from Actinomycetes and Fungi
### Isoflavonoids
#### 2.1.2 Isoflavonoid Glycosides  
Three novel isoflavonoid glycosides, daidzein-4\({}^{\prime}\)-(2-deoxy-\(\alpha\)-L-tucopyranoside) (**20**), daidzein-7-(2-deoxy-\(\alpha\)-L-tucopyranoside) (**21**) and daidzein-4\({}^{\prime}\),7-di-(2-deoxy-\(\alpha\)-L-tucopyranoside) (**71**) were obtained from the culture broth of mangrove-derived actinomycete _Micromonspora aurantiaca_ 110B. Though the new compounds were unable to inhibit pathogenic fungus or bacteria, they exhibited moderate cytotoxic activities to the human colon tumor cell line HCT116, the human lung carcinoma cell line A549, and hepatocellular liver carcinoma cell line HepG2 [43]. Four isoflavone glycosides were obtained from _S. xanthophaeus_. They were identified as daidzein-4\({}^{\prime}\),7-di-\(\alpha\)-L-rhamoside (**22**), daidzein-7-\(\alpha\)-L-rhamnoside (**23**), genisteinin-4\({}^{\prime}\),7-di-\(\alpha\)-L-rhamnoside (**24**), and genisteinin-7-\(\alpha\)-L-rhamnoside (**25**). All of these compounds had \(\beta\)-galactosidaseoshibiting activities [40].  
From the fermentation broth of the lichen-associated _Amyclatops_ sp. YIM 130642, a new isoflavonoid glycoside, 7-\(O\)-methyl-5-\(O\)-\(\alpha\)-L-rhamnopyranosylgenistein (**26**), along with a firstly natural occurring isoflavenoid glycoside, 7-\(O\)-\(\alpha\)-D-arabinofuranosyl daidzein (**27**) was isolated. Compound **26** showed moderate inhibitory activity towards _E. coli_ and _S. aureus_ with MIC value of 64 \(\mu\)g/mL [33]. A new isoflavone glycoside, 4\({}^{\prime}\),7-bis-(\(\beta\)-cyanopyranosyl)-genistein (**28**) was isolated from _Streptomyces_ sp. HKI 129-L [35].  
Ten isoflavonoid glycosides were isolated from _Streptomyces_ sp. RB1 originating from _M. natalensis_, including three novel ones, termisoflavones A-C (**29-31**) and seven known compounds, daidzein-4\({}^{\prime}\),7-di-\(\alpha\)-L-rhamnoside (**22**), daidzein-7-\(\alpha\)-L-rhamnoside (**23**), genisteinin-4\({}^{\prime}\),7-di-\(\alpha\)-L-rhamnoside (**24**), genisteinin-7-\(\alpha\)-L-rhamnoside (**25**), 6-\(O\)-methyl-7-\(O\)-\(\alpha\)-L-rhamnopyranosyldaidzein (**32**), genistin (**33**), and daidzin (**34**). Unfortunately, these compounds showed no antimicrobial activities. Only compounds **23** and **34** showed protective effects on kidney cells [17].  
One new isoflavonoid glycoside, termisoflavone D (**35**), together with six known analogues, daidzein-4\({}^{\prime}\),7-di-\(\alpha\)-L-rhamnopyranoside (**22**), daidzein-7-\(\alpha\)-L-rhamnopyranoside (**23**), genisteinin-4\({}^{\prime}\),7-di-\(\alpha\)-L-rhamnopyranoside (**24**), genisteinin-7-\(\alpha\)-D-glucopyranoside (**33**), daidzein-7-\(\alpha\)-D-glucopyranoside (**34**), and 4\({}^{\prime}\)-O-methyl-7-\(O\)-\(\alpha\)-L-rhamnopyranosylgenistein (**36**), were identified from _Streptomyces_ sp. RB1. Compound **23** prevented glutamate-induced HT22 cell death by blocking the accumulation of intracellular reactive oxygen species (ROS) [41]. Three isoflavpose glycosides, genistin (**33**), daidzin (**34**), and glycitin (**37**), were derived from _Streptomyces_ strain YIM GS3536 [42]. Daidzein-7-\(O\)-\(\alpha\)-L-rhamnoside (**23**) and genisteinin-7-\(O\)-\(\alpha\)-L-rhamnoside (**25**) were derived from Indonesian actinomycete _Streptomyces_ sp. TPU1401A [32].