Inhibitory effects of maesanin and analogs on arachidonic acid metabolizing enzymes.

The substituted 1,4-benzoquinone, maesanin (1), is a potent 5-lipoxygenase (5-LO) inhibitor present in the fruit of Maesa lanceolata Forssk. Thirteen natural, synthetic, semisynthetic, and microbially transformed analogs of 1 were tested for their in vitro inhibition of 5-lipoxygenase (5-LO) and cyclooxygenase-1 (COX-1). Maesanin was the most active 5-LO inhibitor. All other analogs were inactive or less active than the natural products as 5-LO inhibitors. None of the tested compounds was strongly active in the COX-1 inhibition assay.

Alkaloids from Haplophyllum tuberculatum.

Two new alkaloids, haplotubinone (3) and haplotubine (4), were isolated from the aerial parts of Haplophyllum tuberculatum together with the known lignan diphyllin. The structures of the new alkaloids were established by spectroscopic methods in conjunction with X-ray crystallographic analysis of 3. In addition, the amide N-(2-phenylethyl)-benzamide has been identified in this source for the first time.

Bioactive 12-oleanene triterpene and secotriterpene acids from Maytenus undata.

The aerial parts of Maytenus undata yielded four new 12-oleanene and 3,4-seco-12-oleanene triterpene acids, namely, 3-oxo-11alpha-methoxyolean-12-ene-30-oic acid (1), 3-oxo-11alpha-hydroxyolean-12-ene-30-oic acid (2), 3-oxo-olean-9(11), 12-diene-30-oic acid (3), and 3,4-seco-olean-4(23),12-diene-3, 29-dioic acid (20-epi-koetjapic acid) (5), together with the known 3, 11-dioxoolean-12-ene-30-oic acid (3-oxo-18beta-glycyrrhetinic acid) (4), koetjapic acid (6), and the 12-oleanene artifact 3-oxo-11alpha-ethoxyolean-12-ene-30-oic acid (7). Koetjapic acid (6) inhibited the growth of Staphylococcus aureus, methicillin-resistant S. aureus, and Pseudomonas aeruginosa, with an MIC range of 3.125-6.25 microg/mL. The new 3,4-secotriterpene acid 20-epi-koetjapic acid (5) potently inhibited rat neonatal brain microglia phorbol ester-stimulated thromboxane B(2) (IC(50) = 0.5 microM) and superoxide anion (IC(50) = 1.9 microM) generation.

Characterization of the major metabolite of sampangine in rats.

Sampangine (1) is a plant-derived antifungal copyrine alkaloid extracted from the stem bark of Cananga odorata. Although it possesses potent in vitro antifungal activity, 1 is devoid of significant and reproducible in vivo activity in a mouse model of cryptococcosis. Speculating that the lack of in vivo activity could be due to metabolism, a study was undertaken to begin to develop an understanding of the pharmacokinetics, and particularly metabolism of 1. Following intraperitoneal administration of 1 to rats, urine was collected, extracted, and chromatographed over a reversed-phase C(18) silica column to yield the major metabolite, SAM MM1 (2), which was identified by NMR and MS to be an O-glucuronide conjugate of sampangine. In addition, two other unstable, structurally uncharacterized minor metabolites were produced, as evidenced by HPLC analysis. Evaluation of the antifungal and antibacterial activities of 2 showed it to have remarkable in vitro activity against Cryptococcus neoformans.

Microbial transformation of benzosampangine.

Microbial transformation studies of the synthetic antifungal alkaloid benzosampangine (1) have revealed that 1 is metabolized by a number of microorganisms. Using a standard two-stage fermentation technique Absidia glauca (ATCC 22752), Cunninghamella blakesleeana (ATCC 8688a), Cunninghamella species (NRRL 5695), Fusarium solani f. sp. cucurbitae (CSIH #C-5), and Rhizopogon species (ATCC 36060) each produced a beta-glucopyranose conjugate of benzosampangine (2). The identity of 2 was established on the basis of spectroscopic data.

2-Hydroxy-5-(ethanolamino)-3-(10'-Z-pentadecenyl)-1,4-benzoquinone, new microbial phase II metabolite of maesanin.

The use of microbial models for biotransformation of the natural benzoquinone, maesanin (1), resulted in the isolation of an ethanolamine conjugate (5) from the culture broth of Debaryomyces polymorphus ATCC 20280. Metabolite 5 was characterized as 2-hydroxy-5-(ethanolamino)-3-(10'-Z-pentadecenyl)-1,4-benzoq uinone. The production of 5 represents a new type of phase II conjugation reaction in microbial systems. The results of preliminary mammalian metabolism of 1 in rats were inconclusive.

Azaanthraquinone: an antimicrobial alkaloid from Mitracarpus scaber.

An ethanolic extract of the aerial parts of Mitracarpus scaber demonstrated good antimicrobial activity. Bioassay directed fractionation of this extract led to the isolation of benz[g]isoquinoline-5,10-dione (1) as an active component. Compound 1 showed significant in vitro inhibitory activity against the AIDS-related pathogens.

Microbial transformation of sampangine.

Microbial transformation studies of the antifungal alkaloid sampangine (2) have revealed that it is metabolized by a number of microorganisms. Using a standard two-stage fermentation technique, Beauvaria bassiana (ATCC 7159), Doratomyces microsporus (ATCC 16225), and Filobasidiella neoformans (ATCC 10226) produced the 4'-O-methyl-beta-glucopyranose conjugate (3), while Absidia glauca (ATCC 22752), Cunninghamella elegans (ATCC 9245), Cunninghamella species (NRRL 5695), and Rhizopus arrhizus (ATCC 11145) produced the beta-glucopyranose conjugate (4). Metabolites 3 and 4 have been characterized on the basis of spectral data. Both 3 and 4 had significant in vitro activity against Cryptococcus neoformans but were inactive against Candida albicans. Metabolite 4 was inactive in vivo in a mouse model of cryptococcosis.

Microbial models of mammalian metabolism of xenobiotics: An updated review.

The utilization of microbes as models for mammalian metabolism of xenobiotics has been well established since the concept was first introduced by Smith and Rosazza in the early seventies. The core assumption of this concept rests on the fact that fungi are eukaryotic organisms that possess metabolizing enzyme systems similar to those present in mammalian systems. Hence, the outcome of xenobiotic metabolism in both systems is expected to be similar, if not identical, and, thus, fungi can be used to predict the outcome of mammalian metabolism of various xenobiotics, including drugs. Utilizing microbial models offers a number of advantages over the use of animals in metabolism studies, mainly reduction in use of animals, ease of setup and manipulation, higher yield and diversity of metabolite production, and lower cost of production. In a continuation to our contribution to this field, this review will outline the results of studies that were conducted over the last seven years to emphasize the similarities between the microbial and mammalian metabolic pathways of xenobiotics through the endorsement of the concept of microbial models of mammalian metabolism .

Antimicrobial properties of Honduran medicinal plants.

Ninety-two plants used in the traditional pharmacopoeia of the Pech and neighboring Mestizo peoples of central Honduras are reported. The results of in vitro antimicrobial screens showed that 19 of the extracts from medicinal plants revealed signs of antifungal activity while 22 demonstrated a measurable inhibitory effect on one or more bacterial cultures. Bioassay-guided fractionation of extracts from Mikania micrantha, Neurolaena lobata and Piper aduncum produced weak to moderately active isolates. The broad spectrum of activity of the extracts helps to explain the widespread use of these plants for wound healing and other applications.

Microbial and mammalian metabolism studies on the semisynthetic antimalarial, deoxoartemisinin.

PURPOSE: Deoxoartemisinin is a semisynthetic antimalarial with potential for treatment of multiple drug resistant malaria. Metabolism studies were conducted to aid in future drug development. METHODS: Microbial model systems were employed which have been shown to be good predictors of mammalian drug metabolites. Metabolism studies using rats were also performed. RESULTS: Three microbial metabolites of deoxoartemisinin were identified (2, 3, and 4). Metabolite 3 was also found in rat plasma. HPLC/MS analyses were performed on the rat plasma using 2, 3, and 4 as standards. All metabolites were thoroughly characterized by 1H and 13C-NMR. An additional rat plasma metabolite was revealed and it was shown not to be 9 alpha-hydroxyartemisinin. CONCLUSIONS: Deoxoartemisinin was metabolized to three microbial metabolites. Metabolism by rats showed the presence of two metabolites in the plasma, one of which was the same as the microbial metabolite.

Antifungal evaluation of pseudolaric acid B, a major constituent of Pseudolarix kaempferi.

Pseudolaric acid B [1] was isolated and identified as the main antifungal constituent of Pseudolarix kaempferi using bioassay-directed fractionation. Pseudolaric acid B was active against Trichophyton mentagrophytes, Torulopsis petrophilum, Microsporum gypseum, and Candida spp., while its methylated or hydrolyzed derivatives were not active against these same organisms. The minimum inhibitory concentrations and minimum fungicidal concentrations of pseudolaric acid B [1] against Candida and Torulopsis species were comparable with those of amphotericin B. The in vivo activity of pseudolaric acid B was evaluated in a murine model of disseminated candidiasis. Pseudolaric acid B [1] reduced the number of recovered colony-forming units significantly at different dosages. Infected mice treated intravenously with pseudolaric acid B [1] also had a longer survival time than those treated with vehicle alone.

Microbial metabolites of ophiobolin A and antimicrobial evaluation of ophiobolins.

Ophiobolin A [1], 3-anhydroophiobolin A [2], ophiobolin B [3], and ophiobolin L [4] were isolated from fermentation broths of Cochliobolus heterostrophus. Preliminary screening showed that a number of organisms were capable of metabolizing the sesterterpene ophiobolin A [1]. Large-scale transformations of ophiobolin A [1] with Polyangium cellulosum produced 6 and 7 while Pseudomonas aeruginosa produced 8. Resting-cell preparations of Penicillium patulum afforded 9 and 10. The structures of these metabolites were established by spectroscopic methods and by comparison of the spectral data with those of the starting material. The antimicrobial activity of the ophiobolins was also evaluated.

Microbial and mammalian metabolism studies of the semisynthetic antimalarial, anhydrodihydroartemisinin.

Microbial metabolism studies of the semisynthetic antimalarial anhydrodihydroartemisinin (1), have shown that it is metabolized by a number of microorganisms. Large scale fermentation with Streptomyces lavendulae L-105 and Rhizopogon species (ATCC 36060) have resulted in the isolation of four microbial metabolites. These metabolites have been identified as a 14-carbon rearranged product (2), 9 beta-hydroxyanhydrodihydroartemisinin (3), 11-epi-deoxydihydroartemisinin (4), and 3 alpha-hydroxydeoxyanhydrodihydroartemisinin (5). Microbial metabolites were completely characterized by spectral methods, including 1H-NMR and 13C-NMR spectroscopy. The structure and stereochemistry of metabolite 2 were unequivocally established by X-ray crystallographic analysis. Thermospray mass spectroscopy/high-performance liquid chromatographic analyses of plasma from rats used in mammalian metabolism studies of 1 have shown microbial metabolite 3 to be the major mammalian metabolite. In vitro antimalarial testing has shown metabolite 3 to possess antimalarial activity.

Antimicrobial properties of alkaloids from Xanthorhiza simplicissima.

The organic extract of the whole plant Xanthorhiza simplicissima was found to exhibit good activity against the AIDS-related opportunistic pathogens Candida albicans, Cryptococcus neoformans, and Mycobacterium intracellularae. Bioassay-directed fractionation of the extract led to the isolation of the known alkaloid berberine as the major active component. A second alkaloid of the isohomoprotoberberine family, puntarenine, was isolated from this plant family for the first time. Puntarenine also showed marginal activity against the dermatophytic fungus Trichophyton mentagrophytes and the yeast Saccharomyces cerevisiae.

Antimicrobial compounds from Petalostemum purpureum.

EtOH extracts of Petalostemum purpureum demonstrated antimicrobial activity against bacteria and fungi. Bioassay-directed fractionation led to the isolation of petalostemumol [1] as the active constituent. Its structure was determined by a single crystal X-ray diffraction analysis. A minor component designated petalostemumol G [3] is believed to be an artifact of the isolation procedure. Its structure was confirmed by a single crystal X-ray analysis of its pentamethylether 2. A number of derivatives of 1 and 3, including the Me- and benzylethers and acetates, were prepared.

Copyrine alkaloids: synthesis, spectroscopic characterization, and antimycotic/antimycobacterial activity of A- and B-ring-functionalized sampangines.

Several A- and B-ring-substituted sampangines were synthesized and evaluated for antifungal and antimycobacterial activity against AIDS-related opportunistic infection pathogens. Electrophilic halogenation provided a channel for structural elaboration of the sampangine B-ring at position 4, while the synthesis of A-ring 3-substituted sampangines and benzo[4,5]sampangine (24) were achieved from the corresponding functionalized cleistopholines. Two-dimensional NMR spectroscopy was used to rigorously characterize the A- and B-ring substituent patterns. Structure-activity relationship studies revealed the activity of the sampangines was enhanced by the presence of a substituent at position 3 or by a 4,5-benzo group.

The metabolism of muzigadial by microorganisms.

1. A total of 114 microorganisms were evaluated for their ability to metabolize the antifungal drimane sesquiterpene, muzigadial. 2. Cryptococcus neoformans was found to convert muzigadial to one major metabolite, identified as a hemiacetal. 3. Streptomyces platensis produced three metabolites: the hemiacetal, its corresponding lactone, and the epoxide of the hemiacetal. 4. Streptomyces spectabilis produced the hemiacetal as well as the epoxy hemiacetal. 5. The proposed structures of all of the metabolites were based on comparisons of the spectroscopic data (1H- and 13C-n.m.r. spectra and mass spectra) between the metabolites and the parent compound. 6. Antimicrobial evaluation of the microbial metabolites indicate that metabolism decreases antifungal activity.

Microbial production of a crisnatol metabolite.

Microbial metabolism studies of crisnatol (1), a new DNA intercalator, has resulted in the isolation and characterization of a major metabolite identified as the C-1 hydroxylated crisnatol (2). The structure of the metabolite was established by comparison of its spectral data to that of crisnatol. Complete 13C-NMR assignments for crisnatol and its C-1 hydroxylated metabolite were also made.

Preparation, characterization, and antiviral activity of microbial metabolites of stemodin.

Screening studies for microbial transformation products of stemodin [2] have identified a number of microbial metabolites. Scale-up fermentation with Rhizopus arrhizus ATCC 11145 and Streptomyces sp. NRRL 5691 have resulted in the production of five metabolites that have been characterized with the use of 2D nmr and X-ray techniques. These metabolites have been identified as 18-hydroxystemodin [6], 16,18-dihydroxystemodin [7], 8 beta-hydroxystemodin [8], 8 beta, 18-dihydroxystemodin [9], and 7 beta, 8 beta-dihydroxystemodin [10]. The antiviral activity and cytotoxicity of the isolated metabolites have been evaluated.