Odor-active alcohols from the fungal transformation of alpha-farnesene

First Phytochemical Profiling and In-Vitro Antiprotozoal Activity of Essential Oil and Extract of Plagiochila porelloides

Volatiles metabolites from the liverwort Plagiochila porelloides harvested in Corsica were investigated by chromatographic and spectroscopic methods. In addition to already reported constituents, three new compounds were isolated by preparative chromatography and their structures were elucidated by mass spectrometry (MS) and NMR experiments. Hence, an atypic aliphatic compound, named 1,2-dihydro-4,5-dehydronerolidol and two isomers, (E) and (Z), possessing an unusual humbertiane skeleton (called p-menth-1-en-3-[2-methylbut-1-enyl]-8-ol) are newly reported and fully characterized in this work. The in vitro antiprotozoal activity of essential oil and extract of P. porelloides against Trypanosoma brucei brucei and Leishmania mexicana mexicana and cytotoxicity were determined. Essential oil and Et₂O extract showed a moderate activity against T. brucei with IC₅₀ values: 2.03 and 5.18 μg/mL, respectively. It is noteworthy that only the essential oil showed a high selectivity (SI = 11.7). Diethyl oxide extract exhibited moderate anticancer (cancerous macrophage-like murine cells) activity and also cytotoxicity (human normal fibroblast) with IC₅₀ values: 1.25 and 2.96 μg/mL, respectively.

An update on the progress of microbial biotransformation of commercial monoterpenes

Monoterpenes, a class of isoprenoid compounds, are extensively used in flavor, fragrance, perfumery, and cosmetics. They display many astonishing bioactive properties of biological and pharmacological significance. All monoterpenes are derived from universal precursor geranyl diphosphate. The demand for new monoterpenoids has been increasing in flavor, fragrances, perfumery, and pharmaceuticals. Chemical methods, which are harmful for human and the environment, synthesize most of these products. Over the years, researchers have developed alternative methods for the production of newer monoterpenoids. Microbial biotransformation is one of them, which relied on microbes and their enzymes. It has produced many new desirable commercially important monoterpenoids. A growing number of reports reflect an ever-expanding scope of microbial biotransformation in food and aroma industries. Simultaneously, our knowledge of the enzymology of monoterpene biosynthetic pathways has been increasing, which facilitated the biotransformation of monoterpenes. In this article, we have covered the progress made on microbial biotransformation of commercial monoterpenes with a brief introduction to their biosynthesis. We have collected several reports from authentic web sources, including Google Scholar, Pubmed, Web of Science, and Scopus published in the past few years to extract information on the topic.

Chemical Composition of Essential Oils from Zanthoxylum bungeanum Maxim. and Their Bioactivities against Lasioderma serricorne

Two essential oil samples were obtained from the pericarp of Zanthoxylum bungeanum with the methods of hydrodistillation (HD) and supercritical fluid CO₂ extraction (SFE), their chemical components were identified, and their bioactivities against Lasioderma serricorne adults were evaluated. In the process of testing, the two samples showed significant bioactivities against Lasioderma serricorne adults. For an example, the SFE-sample expressed relatively stronger fumigant toxicity on Lasioderma serricorne adults (LC₅₀ = 3.99 μg/mL air) than that of the HD-sample (LC₅₀ = 12.54 μg/mL air). According to GC-MS analysis, the chemical components between two samples were different. The major chemical components for HD included linalool (25.99%), limonene (19.34%), linalyl anthranilate (12.22%), 4-terpinenol (10.49%), eucalyptol (6.53%) and α-terpineol (5.02%), while for SFE included nonanoic acid (21.43%), γ-terpinene (14.51%), eucalyptol (13.45%), α-terpineol (5.83%) and caryophyllene oxide (5.48%). The results showed that different chemical components result in different bioactivities. This work provides theoretical basis for traditional Chinese concept of antagonistic storage, and it also provides important information for the development and comprehensive utilization of Zanthoxylum bungeanum.

Identification of Repellent and Insecticidal Constituents fromArtemisia mongolicaEssential Oil againstLasioderma serricorne

The aims of this research were to determine the chemical composition and insecticidal and repellent activities of theArtemisia mongolicaessential oil againstLasioderma serricorneand to isolate active constituents from the essential oil. The essential oil ofA. mongolicawas obtained by hydrodistillation and 36 components were identified with GC-MS. Eucalyptol (39.88%), (S)-cis-verbenol (14.93%), 4-terpineol (7.20%), (−)-camphor (6.02%), andα-terpineol (4.20%) were found to be major components. With a further isolation process, five constituents obtained from the essential oil were identified as eucalyptol, verbenol, 4-terpineol, camphor, andα-terpineol. In the progress of assay, it showed thatL. serricorneadults had different sensitivities to the crude essential oil and isolated constituents. 4-Terpineol exhibited strongest contact activity againstL. serricorne, showing the LD50value of 8.62 μg/adult. Moreover, camphor andα-terpineol showed stronger fumigant activity (LC50=2.91and 3.27 mg/L air, resp.) againstL. serricornethan crude essential oil and other constituents. In addition, the essential oil, eucalyptol, verbenol, andα-terpineol showed comparable repellency againstL. serricorneadults. The results indicate that the essential oil and isolated compounds have potential to provide more efficient and safer natural insecticides or repellents for control of insects in food and Chinese medicinal materials preservation.

Fumigant Compounds from the Essential Oil of ChineseBlumea balsamiferaLeaves against the Maize Weevil (Sitophilus zeamais)

Essential oil of Chinese medicinal herb,Blumea balsamiferaleaves, was found to possess fumigant toxicity against the maize weevils,Sitophilus zeamais. The main components of the essential oil ofB. balsamiferawere 1,8-cineole (20.98%), borneol (11.99%),β-caryophyllene (10.38%), camphor (8.06%), 4-terpineol (6.49%),α-terpineol (5.91%), and caryophyllene oxide (5.35%). Bioactivity-guided chromatographic separation of the essential oil on repeated silica gel columns led to isolate five constituent compounds, namely, 1,8-cineole, borneol, camphor,α-terpineol, and 4-terpineol. 1,8-Cineole, 4-terpineol, andα-terpineol showed pronounced fumigant toxicity againstS. zeamaisadults (LC50= 2.96 mg/L, 4.79 mg/L, and 7.45 mg/L air, resp.) and were more toxic than camphor (LC50= 21.64 mg/L air) and borneol (LC50= 21.67 mg/L air). The crude essential oil also possessed strong fumigant toxicity againstS. zeamaisadults (LC50= 10.71 mg/L air).

The use of endophytes to obtain bioactive compounds and their application in biotransformation process

Endophytes are microorganisms that reside asymptomatically in the tissues of higher plants and are a promising source of novel organic natural metabolites exhibiting a variety of biological activities. The laboratory of Bioaromas (Unicamp, Brazil) develops research in biotransformation processes and functional evaluation of natural products. With the intent to provide subsidies for studies on endophytic microbes related to areas cited before, this paper focuses particularly on the role of endophytes on the production of anticancer, antimicrobial, and antioxidant compounds and includes examples that illustrate their potential for human use. It also describes biotransformation as an auspicious method to obtain novel bioactive compounds from microbes. Biotransformation allows the production of regio- and stereoselective compounds under mild conditions that can be labeled as "natural," as discussed in this paper.

Terpene Bioconversion – How does its Future Look?

The usage of essential oils as such or of volatile fractions thereof is widespread in the flavor and fragrance industry to aromatize perfumery and cosmetic products, foodstuffs, and many household and pharmaceutical products. The increased market share of convenience food together with consumers’ request for constant high quality and natural products have established a lasting increase in the demand for natural flavorings that cannot be satisfied by the traditional plant materials. This review summarizes selected work on terpene bioconversion / transformation and focuses on recently published papers dealing with novel strains and products, high product yields, intriguing genetic engineering approaches, and integrated bioprocesses. The future perspectives of an industrial realization of a biotechnological production of terpene-derived natural flavors are critically evaluated.

Crystal structure of albaflavenone monooxygenase containing a moonlighting terpene synthase active site

Albaflavenone synthase (CYP170A1) is a monooxygenase catalyzing the final two steps in the biosynthesis of this antibiotic in the soil bacterium, Streptomyces coelicolor A3(2). Interestingly, CYP170A1 shows no stereo selection forming equal amounts of two albaflavenol epimers, each of which is oxidized in turn to albaflavenone. To explore the structural basis of the reaction mechanism, we have studied the crystal structures of both ligand-free CYP170A1 (2.6 A) and complex of endogenous substrate (epi-isozizaene) with CYP170A1 (3.3 A). The structure of the complex suggests that the proximal epi-isozizaene molecules may bind to the heme iron in two orientations. In addition, much to our surprise, we have found that albaflavenone synthase also has a second, completely distinct catalytic activity corresponding to the synthesis of farnesene isomers from farnesyl diphosphate. Within the cytochrome P450 alpha-helical domain both the primary sequence and x-ray structure indicate the presence of a novel terpene synthase active site that is moonlighting on the P450 structure. This includes signature sequences for divalent cation binding and an alpha-helical barrel. This barrel is unusual because it consists of only four helices rather than six found in all other terpene synthases. Mutagenesis establishes that this barrel is essential for the terpene synthase activity of CYP170A1 but not for the monooxygenase activity. This is the first bifunctional P450 discovered to have another active site moonlighting on it and the first time a terpene synthase active site is found moonlighting on another protein.

In vivo ESR spin trapping detection of carbon-centered alpha-Farnesene radicals

Lyophilisates of the ascomycetes Penicillium solitum and Aspergillus niger converted alpha-farnesene to 7-hydroxyfarnesene as the major product. The radical mechanism of this bioconversion was proven by electron spin resonance (ESR) and GC-MS using the spin trapping technique. Intermediate carbon-centered radicals of alpha-farnesene were captured using two spin traps, 2-methyl-2-nitrosopropane and alpha-(4-pyridyl-1-oxide)- N- tert-butylnitrone, respectively. The evaluation of the coupling constants and hyperfine couplings of the ESR spectra showed that tertiary carbon radicals were trapped. The radical position at C7 of alpha-farnesene was derived from EI and CI mass spectra of the corresponding MNP spin adduct. The present study demonstrates that the complementary application of ESR and MS spectrometric data allows the detailed evaluation of a radical mechanism of a fungal terpene transformation reaction.

Oxidation products of alpha-farnesene associated with superficial scald development in d'Anjou pear fruits are conjugated trienols

Conjugated triene (CT) oxidation products of the acyclic sesquiterpene (E,E)-alpha-farnesene are thought to induce development of the physiological storage disorder superficial scald in apple and pear fruits of susceptible cultivars. CTs that accumulate in peel tissues of Granny Smith and Delicious apples after several weeks of cold storage are known to be conjugated trienols (CTols) rather than the corresponding hydroperoxides produced by in vitro autoxidation of alpha-farnesene. Here, it is shown that CTols are also the predominant in vivo oxidation products of alpha-farnesene in cold-stored pear fruit of the highly scald-susceptible d'Anjou cultivar. Analysis by octadecylsilane reversed phase high-performance liquid chromatography with diode array detection, gas chromatography with flame ionization detection, gas chromatography-mass spectrometry, and proton nuclear magnetic resonance spectroscopy identified 3,7,11-trimethyldodeca-1,3(E),5(E),10-tetraen-7-ol as the major CT in hexane extracts of peel tissue from d'Anjou pears stored for 3-5 months in air at -1 degrees C. The possible origins of CTols in apples and pears and the hypothesized role of these oxidation products of alpha-farnesene in the induction of scald are discussed. .