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FIGURE 15.84 Biotransformation of cadina-4,10(15)-dien-3-one (265) by Beauveria bassiana.

FIGURE 15.84 Biotransformation of cadina-4,10(15)-dien-3-one (265) by Beauveria bassiana.

The insecticidal potential of the metabolites (267, 268, 268a-268f) were evaluated against Cylas formicarius. The metabolites (273, 268, 268d) showed enhanced activity compared with the substrate (265). The plant growth regulatory activity of the metabolites against radish seeds was tested. All the compounds showed inhibitory activity; however, their activity was less than colchicine (Buchanan et al., 2000) (Figure 15.84).

Cadinane-type sesquiterpene alcohol (281) isolated from the liverwort Mylia taylorii gave a primary alcohol (282) by Aspergillus niger treatment (Morikawa et al., 2000) (Figure 15.85).

Fermentation of (-)-a-bisabolol (282a) possessing anti-inflammatory activity with plant pathogenic fungus Glomerella cingulata for 7 days yielded oxygenated products (282b-282e) of which compound 282e was predominant. 3,4-Dihydroxy products (282b, 282d, 282e) could be formed by hydrolysis of the 3,4-epoxide from 282a and 282c (Miyazawa et al., 1995b) (Figure 15.86).

El Sayed et al. (2002) reported microbial and chemical transformation of (S)-(+)-curcuphenol (282g) and curcudiol (282n), isolated from the marine sponges, Didiscus axeata. Incubation of compound 282g with Kluyveromyces marxianus var. lactis resulted in the isolation of six metabolites (3-8, 282h-282j). The same substrate was incubated with Aspergillus alliaceus to give the metabolites (282p, 282q, 282s) (Figure 15.87).

Compounds 282g and 282n were treated in Rhizopus arrhizus and Rhodotorula glutinus for 6 and 8 days to afford glucosylated metabolites, 1a-D-glucosides (282o) and 282r, respectively. The

substrate itself showed antimicrobial activity against Candia albicans, Cryptococcus neoformans, and MRSA-resistant Staphylococcus aureus and Staphylococcus aureus with MIC and MFC/MBC ranges of 7.5-25 and 12.5-50 mg/mL, respectively. Compounds 282g and 282h also exhibited in vitro antimalarial activity against Plasmodium falciparium (D6 clone) and Plasmodium falciparum (W2 clone) of 3600 and 3800 ng/mL (selective index (S.I.) > 1.3), and 1800 (S.I. > 2.6), and 2900 (S.I. > 1.6), respectively (El Sayed et al., 2002) (Figure 15.87).

Artemisia annua is one of the most important Asteraceae species as antimalarial plant. There are many reports of microbial biotransformation of artemisinin (283), which is active antimalarial rearranged cadinane sesquiterpene endoperoxide, and its derivatives to give novel antimalarials with increased activities or differing pharmacological characteristics.

Lee et al. (1989) reported that deoxoartemisinin (284) and its 3a-hydroxy derivative (285) were obtained from the metabolites of artemisinin (283) incubated with Nocardia corallina and Penicillium chrysogenum (Figure 15.88).

Zhan et al. (2002) reported that incubation of artemisinin (283) with Cunninghamella echinulata and Aspergillus niger for 4 days at 28°C resulted in the isolation of two metabolites, 10b -hydroxyar-temisinin (287a) and 3a-hydroxydeoxyartemisinin (285), respectively.

Compound 283 was also biotransformed by Aspergillus niger to give four metabolites, deoxyar-temisinin (284, 38%), 3a-hydroxydeoxyartemisinin (285, 15%), and two minor products (286, 8% and 287, 5%) (Hashimoto et al., 2003b).

Artemisinin (283) was also bioconverted by Cunninghamella elegans. During this process, 9b-hydroxyartemisinin (287b, 78.6%), 9b -hydroxy-8a-artemisinin (287c, 6.0%), 3a- hydroxydeox-oartemisinin (285, 5.4%), and 10b-hydroxyartemisinin (287d, 6.5%) have been formed. On the basis of quantitative structure-activity relationship (QSAR) and molecular modeling investigations, 9b-hydoxy derivatization of artemisinin skeleton may yield improvement in antimalarial activity and may potentially serve as an efficient means of increasing water solubility (Parshikov et al., 2004) (Figure 15.89).

Albicanal (288) and (-)-drimenol (289) are simple drimane sesquiterpenoids isolated from the liverwort, Diplophyllum serrulatum, and many other liverworts and higher plants. The latter compound was incubated with Mucor plumbeus and Rhizopus arrhizus. The former microorganism converted 289 to 6,7a-epoxy- (290), 3b -hydroxy- (291), and 6a-drimenol (292) in the yields of 2%, 7%, and 50%, respectively. On the other hand, the latter species produced only 3b -hydroxy derivative (291) in 60% yield (Aranda et al., 1992) (Figure 15.90).

(-)-Polygodial (293) possessing piscicidal, antimicrobial, and mosquito-repellant activity is the major pungent sesquitepene dial isolated from Polygonum hydropiper and the liverwort, Porella vernicosa complex. Polygodial was incubated with Aspergillus niger, however, because of its

282r

FIGURE 15.87 Biotransformation of (S)-(+)-curcuphenol (282g) by Kluyveromycesmarxianus and Rhizopus arrhizus and curcudiol (282n) by Aspergillus alliaceus and Rhodotorula glutinus.

282r

FIGURE 15.87 Biotransformation of (S)-(+)-curcuphenol (282g) by Kluyveromycesmarxianus and Rhizopus arrhizus and curcudiol (282n) by Aspergillus alliaceus and Rhodotorula glutinus.

antimicrobial activity, nothing metabolite was obtained (Sekita et al., 2005). Polygodiol (295) prepared from polygodial (293) was also treated in the same manner as described above to afford 3ß-hyrdoxy- (297), which was isolated from Marasmius oreades as antimicrobial activity (Ayer and Craw, 1989) and 6a-hydroxypolygodiol (298) in 66-70% and 5-10% yields, respectively (Aranda et al., 1992). The same metabolite (297) was also obtained from polygodiol (295) as a sole metabolite from the culture broth of Aspergillus niger in Czapek-peptone medium for 3 days in 70.5% yield (Sekita et al., 2005), while the C9 epimeric product (296) from isopolygodial (294) was incubated with Mucor plumbeus to afford 3ß-hydroxy- (299) and 6a-hydroxy derivative (300) in low yields,

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