Phytochemistry Reviews (v.11, #4)

Essential oils from Asteraceae as potential biocontrol tools for tomato pests and diseases by María Laura Umpiérrez; María Eugenia Lagreca; Raimundo Cabrera; Gabriela Grille; Carmen Rossini (339-350).
Nowadays, new strategies for pest and disease control to be used in rotation with or replacement of conventional pesticides are required. Essential oils (EOs), as botanical pesticides, provide a potential resource to develop more environmentally friendly and less toxic means of control to be applied in different produces. Tomato crop is affected by many insects and fungal diseases, among which, the insects Trialeurodes vaporariorum and Tuta absoluta, and the fungi Alternaria spp. and Botrytis cinerea are of great incidence. In this work two EOs from Uruguayan specimens of the local species Eupatorium buniifolium and the world-wide distributed Artemisia absinthium (Asteraceae) were characterized in their chemical composition and insecticidal and antifungal activities. We found that the EO from local A. absinthium is rich in oxygenated monoterpenes and belongs to the thujone chemotype (β-Thujone abundance is 56 ± 2 %, and α-Thujone, 1.67 ± 0.07 %). On the other hand, monoterpene hydrocarbons (α-Pinene, 22 ± 2 %) and sesquiterpene hydrocarbons [(E)-β-Guaiene, 10 ± 1 %] are the most abundant components of E. buniifolium EO. Eventhough both EOs chemically differ, they exhibit insecticidal and antifungal activity not only by direct contact but also by contact with their vapors against the tested organisms. These results may indicate that these EOs could be raw material to develop control agents to manage some of the main pests and fungal diseases of tomato crops with only one kind of treatment.
Keywords: Artemisia absinthium ; Eupatorium buniifolium ; Tuta absoluta ; Trialeurodes vaporariorum ; Antifungal activity

Botanical nematicides in the mediterranean basin by Nikoletta G. Ntalli; Pierluigi Caboni (351-359).
Achieving food sufficiency in a sustainable manner is a major challenge for farmers, agro-industries, researchers and governments. Amongst agricultural pests supressing crops, root-knot nematodes (Meloidogyne spp.) represent possibly the world’s most damaging one, the control of which has been mainly based on chemical nematicides. In the recent years the environmental, food safety and animal welfare issues pose the need for alternative nematode control measures. Screening naturally occurring compounds in plants, involved in the complex chemical-mediated interactions between a plant and other organisms in its environment, can provide with innovative nematode control measures that can be safely used in integrated pest management programs. The Mediterranean Basin is an area where various soils and climatic conditions allow a vast plant biodiversity providing with chemical botanicals of significant nematicidal potency. This is a review on the Mediterranean botanicals that can control Meloidogyne spp.
Keywords: Meloidogyne ; Botanicals; Nematicide; Biopesticide; Plant secondary metabolites

Essential oils for the control of reduviid insects by Paula Sainz; Jesús Sanz; Jesús Burillo; Azucena González-Coloma; María Bailén; Rafael A. Martínez-Díaz (361-369).
Chagas disease is an important vector-borne disease problem in South America, especially in rural areas where inhabitants are in contact with the reduviid insects that transmit the parasite Trypanosoma cruzi. Today, the main means of interrupting transmission of T. cruzi is to control the vector. Therefore, studies of new agents with activity against these vectors have a priority interest. This review covers recent studies on essential oils from plants that have demonstrated moderate to high activity against the main vectors of Chagas disease. Further, we investigate the constituents of essential oils of plants of the genera Mentha, Thymus, Satureja and Artemisia and their activity on Rhodnius prolixus using an excito-repellency test.
Keywords: Activity; Chagas disease; Excito-repellency; Rhodnius prolixus

Nematicidal activity of essential oils: a review by Maria Fe Andrés; Azucena González-Coloma; Jesus Sanz; Jesus Burillo; Paula Sainz (371-390).
Plant parasitic nematodes are the most destructive group of plant pathogens worldwide and their control is extremely challenging. Plant Essential oils (EOs) and their constituents have a great potential in nematode control since they can be developed for use as nematicides themselves or can serve as model compounds for the development of derivatives with enhanced activity. This study reviews the plant EOs evaluated as potential nematicides and their toxic effects against pinewood nematode (Bursaphelenchus xylophilus) and root-knot nematodes (Meloidogyne spp.). Additionally, the nematicidal activity to M. javanica of several EOs from Spanish aromatic plants and their components is described.
Keywords: Essential oils; Nematicidal activity; Root-knot nematodes; Meloidogyne ; Pinewood nematode; Bursaphelenchus xylophilus ; Hyssopus officinalis ; Lippia alba ; Mentha arvensis ; M. longifolia ; M. piperita ; M. rotundifolia ; M. spicata ; Satureja montana ; Thymus mastichina ; T. vulgaris ; T. zygis

Plant-defensive sesquiterpenoids from Senecio species with biopesticide potential by A. G. Portero; A. González-Coloma; M. Reina; C. E. Díaz (391-403).
Senecio species have been used in folk medicine for treatment of wounds, as antiemetic, anti-inflammatory and their crude extract or dry powder as crop protection agents. The toxicity exhibited to livestock by these plants has been attributed to their content in pyrrolizidine alkaloids and furanoeremophilane type sesquiterpenes. Sesquiterpenoids with eremophilane, cacalol, bisabolane, silphinene, caryophillane, humulane, germacrane and benzofurane skeletons have been isolated from this genus. Here we focus on bioactive sesquiterpenoids with plant defensive properties isolated from Senecio.
Keywords: Sesquiterpenes; Insects; Antifeedant; Structure–activity relationships; Crop protection

Determination of antibacterial activity of vacuum distillation fractions of lemongrass essential oil by Manuel A. Falcão; Ana L. B. Fianco; Aline M. Lucas; Marcos A. A. Pereira; Fernando C. Torres; Rubem M. F. Vargas; Eduardo Cassel (405-412).
Essential oils are natural substances composed of terpenoids and phenylpropanoid molecules that have many biological activities. Because of their activity, essential oils are widely used in foods, cosmetics, and pharmaceutical products, but new applications of such mixtures are still dependent on separation processes that are able to produce compounds with specific standardized and reproducible compositions. This work studies the fractionation of lemongrass essential oil by vacuum distillation with the goal of obtaining an antimicrobial fraction that acts against Salmonella choleraesuis, Pseudomonas aeruginosa and Staphylococcus aureus. The samples were analyzed by gas chromatography–mass spectrometry and evaluated for antimicrobial activity using the indirect bioautography method and minimum inhibitory concentrations. Vacuum distillation was found to be an efficient method for obtaining distinct fractions with increased antimicrobial activity. The fractions that showed the best response against the three microorganisms tested were F3b, F3a1, F2, F3a2 and F1, with the most effective being F3a2, which also presented the highest yield.
Keywords: Antibacterial activity; Bioautography; Lemongrass essential oil; Minimal inhibitory concentration; Steam distillation

Supercritical methodologies applied to the production of biopesticides: a review by L. Martín; J. L. Marqués; A. González-Coloma; A. M. Mainar; A. M. F. Palavra; J. S. Urieta (413-431).
Supercritical technologies are new, environmentally friendly, advanced separation techniques that have attracted the attention of both industry and academy in their aspirations of producing safer products with cleaner processes. In the field of biopesticides, supercritical fluids are being used in different stages, from the extraction of active ingredients from natural matrices to the encapsulation of blends during the formulation of the final commercial pesticide. This review summarizes different supercritical processes that arise in literature comprising supercritical fluid extraction, supercritical antisolvent fractionation or extraction, supercritical assisted atomization, particle from gas saturated solutions and supercritical solvent impregnation among others. The aim of this work is to give a general view of supercritical fluids in the field of biopesticides production, optimization and formulation, emphasizing in the extraction, fractionation and encapsulation and highlighting their importance when green, solvent free processes have to be designed.
Keywords: Natural pesticides; Extraction; Formulation; Fractionation; Supercritical fluids

Supercritical extraction and supercritical antisolvent fractionation of natural products from plant material: comparative results on Persea indica by A. Gonzalez-Coloma; L. Martín; A. M. Mainar; J. S. Urieta; B. M. Fraga; V. Rodríguez-Vallejo; C. E. Díaz (433-446).
Supercritical fluids (SCFs) are alternative solvents in the field of Green Chemistry that are being developed as advanced separation techniques due to their combined properties such as the penetrability of a gas and the solvent power of a liquid. These characteristics are used in the supercritical fluid extraction (SFE), where compounds of interest can be extracted after mixing a SCF as a solvent with a matrix in a pressurized vessel. Supercritical antisolvent fractionation (SAF) uses the SCF as antisolvent, allowing for the precipitation of insoluble compounds in the SCF-organic solution mixture. An updated overview of SFE and SAF of natural products is presented in this article. Additionally we compare the results of SFE, SAF and organic soxhlet extraction (OSE) of Persea indica, a Macaronesian paleoendemism with strong insecticidal components. The composition of the extracts was analyzed by HPLC-MS, showing in the SFE extracts as major components ryanodol, cinnzeylanol and alkyl-γ-lactones, with their abundance varying with the extraction conditions. On the other hand, the SAF allowed for the fractionation of a liquid solution to give a ryanodol enriched extract (31 % more ryanodol than the initial ethanolic solution). The antifeedant and postingestive effects of these extracts on Spodoptera littoralis showed that the SAF extracts were the most active followed by SFE and OSE and their different effects can be partially explained by their composition.
Keywords: Supercritical fluid extraction; Supercritical antisolvent fractionation; Biopesticide; Persea indica

Agricultural residues as a source of bioactive natural products by Omar Santana-Méridas; Azucena González-Coloma; Raúl Sánchez-Vioque (447-466).
Agricultural industry produces billions of tons of residues in non-edible portions derived from the cultivation and processing of a particular crop. These residues can cause pollution, management and economic problems worldwide. This is the reason for the development of different strategies to use agricultural and industrial residues as a source of high value-added products. This review gives an overview of the potential of agricultural residues as raw materials for the production of bioactive products considering their availability, processing, and their chemical and biological properties. We also provide new data on the potential as biopesticides of some selected crop- and processing-based residues.
Keywords: Bioactive compounds; Biopesticidal activity; Waste management; Crop-based residues; Processing-based residues

Endophytic fungi and their metabolites isolated from Indian medicinal plant by Kanika Chowdhary; Nutan Kaushik; Azucena Gonzalez Coloma; Cabrera Manuel Raimundo (467-485).
Endophytic fungi have been creating a considerable interest and curiosity among researchers since past three decades globally, owing to their recognition as an inexhaustible source of structurally and biologically novel compounds, alternative source of metabolites functionally identical to plant produced metabolites and their ability to impart resistance in host plants against various biotic and abiotic stresses. In this review, we have earnestly attempted to compile a vast array of endophytic fungi assemblages harbored inside Indian medicinal plants which have been reported during last decade from India.
Keywords: Balanced antagonism; Endophytic fungi; Medicinal plants; Secondary metabolites

Endophytic fungi from medicinal plants: a treasure hunt for bioactive metabolites by Sanjana Kaul; Suruchi Gupta; Maroof Ahmed; Manoj K. Dhar (487-505).
Endophytic fungi are ubiquitous organisms found in the plants, residing intercellular or intracellular, at least for a portion of their lives without causing apparent symptoms of infection. Almost all plants are known to harbor endophytes. The choice of the plant to be used for exploring endophytes for bioactives is important. Therefore, medicinal plants which are known to be used since centuries as an alternative source of medicine, are a valuable source for bioprospecting endophytes. Nevertheless, due to many reasons there is a dire need for novel resources for novel drugs which can be an answer to many deadly diseases. It is in this context that the present review was envisaged. The review reveals the importance of endophytic fungi from medicinal plants as a source of bioactive and chemically novel compounds. The bioactive metabolites produced by endophytic fungi originate from different biosynthetic pathways and belong to diverse structural groups such as terpenoids, steroids, quinones, phenols, coumarins etc. Endophytes therefore, represent a chemical reservoir for new compounds such as, anticancer, immunomodulatory, antioxidant, antiparasitic, antiviral, antitubercular, insecticidal etc. for use in the pharmaceutical and agrochemical industries. Although, efforts have been made to accommodate as many examples as possible but the depth of the subject is so vast that it cannot be covered in one single review. This in itself speaks of the fact that endophytic fungi from medicinal plants is indeed a treasure worth searching. In the present review only some selected examples have been covered.
Keywords: Bioactivities; Endophytes; Medicinal plants; New metabolites

Endophytic fungi are known to harbour compound(s) beneficial for plant health as well as human health. Among the metabolites of agrochemical and pharmaceutical importance alkaloids are the major. Apart from alkaloids several terpernoids and steroids, isocoumarins and chromones, phenolics and volatiles have also been reported. Cryptocin and cytochalasins alkaloids were isolated during early phase of innovation and proved to be antifungal. Some of these metabolites produced by endophytic fungi were originally isolated from the host plants.
Keywords: Antifungal; Biofungicide; Endophytic fungi; Fungal metabolites

Phytochemical and pharmacological studies in genus Berberis by Daya Bhardwaj; Nutan Kaushik (523-542).
The genus Berberis is well known for its diversity and pharmacological uses in traditional medicine system since ancient time. Exploring this medicinal plant with more prominence is the need of present day medicinal system. The present review highlighted the phytochemical and pharmacological studies reported from genus Berberis over the last two decades.
Keywords: Berberis ; Barberry; Phytochemical; Pharmacological; Traditional medicine

Phytochemical feeding deterrents for stored product insect pests by Jan Nawrot; Juraj Harmatha (543-566).
This review summarises information on compounds of plant origin and plant products as feeding inhibitors for stored product insects. More than 200 compounds (mostly sesquiterpenes) and over 160 plant extracts have been tested to date. Indeed, we did not consider substances stimulating olfactory receptors (repellents) or compounds just toxic to insects. The main scope of the review is to enable best choice for the most active, as well as biorationally suitable substances, for evolving further rational experiments in future. Feeding inhibitors may be used along with food or sex attractants in biorational control of the stored food pests. However, each semiochemical should be submitted to a formal registration process before its use in practice.
Keywords: Insect feeding deterrence; Antifeedant phytochemicals; Isoprenoids; Sesquiterpene lactones; Polyphenols

The therapeutic lead potential of metabolites obtained from natural sources for the treatment of peptic ulcer by Luiz Carlos Klein-Júnior; José Roberto Santin; Rivaldo Niero; Sérgio Faloni de Andrade; Valdir Cechinel-Filho (567-616).
For over a century, ulcer has been a major cause of morbidity and mortality. Its treatment has progressed from vagotomy to proton pump inhibitors. However, the drugs used produce many adverse effects and are less effective than they ought to be. Therefore, there is a growing interest in alternative therapies and the use of natural products. This review emphasizes recent studies involving naturally occurring antiulcer metabolites, categorized according to their chemical structure. Both terrestrial and marine sources are included. More than a hundred and fifty different compounds are presented, and where possible, their main mechanisms of action are summarized. Considering that Helicobacter pylori is an important causal factor in the pathogenesis of ulcer disease, an overview of some natural compounds with anti-H. pylori activity is presented.
Keywords: Ulcer; Secondary metabolites; Gastroprotection