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Secondary metabolites extracted from plants have historically been critical for drug discovery, but their isolation involves expensive and complicated procedures in terms of time and labor resources. Thus, the biogenetic pathway offers the possibility of identifying specific compounds that have not yet been isolated and predicting their isolation from specific natural sources. In plants, biphenanthrenes represent a relatively small group of aromatic secondary metabolites that are considered as important taxonomic markers with promising biological activities. To date, 38 mixed phenanthrenoid dimers have been identified, the biosynthesis of which involves the radical coupling of the two subunits, namely, a phenanthrene and a dihydrophenanthrene. For each of the compounds, it is possible to identify the single phenanthrenic and dihydrophenanthrenic units constituting the considered dimer. Based on the biogenetic pathway, it is possible to identify 19 phenanthrenes and 17 dihydrophenanthrenes, and to distinguish those already known from those not yet isolated. By comparing the results of the possible biosynthetic pathway for each compound with the data in the literature, it is possible to identify three known phenanthrenes and seven known dihydrophenanthrenes, as well as eleven new phenanthrenes and five new dihydrophenanthrenes, and to identify from which plant it is possible to isolate them. This could direct the work of researchers seeking to identify known or new molecules useful for their possible biological properties, and ultimately, to confirm the veracity of the proposed and generally accepted biosynthetic pathway. [ABSTRACT FROM AUTHOR]

New allelochemicals were identified through bio-guided fractionation from the ethyl acetate of seeds extracts, which was the most autotoxic compared to the other plant parts. Phytochemical investigation of the seeds extracts of C. arabica by spectroscopy analyses has led to identify two new dammarane type triterpenes (4 and 9), with nine known analogues (1 − 3, 5 − 8, 10 and 11), a new cucurbitane triterpene (12), acylated dehydrodiconiferyl alcohol (13), and three highly oxygenated flavonols (14−16). The most autotoxic compounds on germination and seedling growth were elucidated as dammarane type triterpenes. However, less autotoxic effect was recorded by an inhibition under 50% for most of the identified flavonoids. These results suggest that those autotoxic substances may be used as a new bio-herbicide that may contribute to manage the distribution of C. arabica in agronomic field. [ABSTRACT FROM AUTHOR]

Phytochemical investigation of the aerial parts of Gymnema sylvestre led to the isolation of two known oleanane-type triterpenes, 1 and 3, five new acylated derivatives, 2, 4, and 5- 7, and a new lupane-type triterpene, 8. The structures and relative configurations of these compounds were elucidated by spectroscopic analyses, including 1D- and 2D-NMR spectroscopy and mass spectrometry, and by the comparison of their NMR data with those of related compounds. [ABSTRACT FROM AUTHOR]

Phytochemical investigation of the aerial parts of Gymnema sylvestre has led to the isolation of seven new triterpenes, six oleane types ( 5, 7- 11) and a new lupane type ( 12), and of the six known analogues 1- 4, 6, and 13. The structures and relative configurations of these compounds were elucidated by spectroscopic analyses, including 1D- and 2D-NMR spectroscopy and mass spectrometry, and by the comparison of their NMR data with those of related compounds. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study that examined the aqueous and organic extracts of the spiderflower, Cleome arabica on its effects on the feeding and survival of larvae of the cotton leafworm, Spodoptera littoralis. The study showed that higher dose of Cleome arabica extracts provided antifeeding and phagostimulating activities against Spodoptera littoralis larvae. The most active was the methanol extract of siliquae.

This study highlights interaction between allelochemicals of Padina pavonica (L), Ulva lactuca (L) and Corallina officinalis (L). Aqueous (30 g/1) and organic (3000 ppm) extracts were mixed to have ten mixtures with different proportions. Extracts and their mixtures were tested on germination and growth of wheat. Results indicate that allelochemicals could interact and their activity could be strengthened or decreased, according to mixtures proportions. Wheat seedlings growth was stimulated by mixtures with high proportion of P. pavonica. This effect was lessened by addition of U. lactuca and/or C. officinalis extracts. Ethanol extracts of P. pavonica and C. officinals induced root growth reduction while U. lactuca ethanol extract reinforced this reduction. For chloroform extracts, C. officinalis extract have mitigated the stimulatory effect of U. lactuca or P. pavonica extracts, resulting in an antagonism. Results are conclusive pushing to exploit the possible synergy and/or antagonism between molecules with interest, highly sought in sustainable development but produced in very limited quantities. [ABSTRACT FROM AUTHOR]

Aqueous (10, 20, 30 & 40 g L-1) and organic (hexane, chloroform & methanol, at 3 & 6 mg mL-1) extracts of Inula viscosa L. (roots, stems, leaves & flowers) were evaluated for their allelopathic activities on radish, lettuce, peganum and thistle. In addition leaf and flower powder was incorporated in soil at 1.25 and 2.5 g kg-1. PEG (Polyethylene glycol) solutions, with similar osmotic potentials of aqueous extracts, at the highest concentration, were without effect on target species, this eliminates the extracts osmotic effect. Germination index was not affected by root and stem extracts and significantly decreased by the two other ones. For growth, leaves and flowers extracts had the most significant toxicity, inducing up to total inhibition. Leaves leachates strongly inhibited seedling growth of lettuce (93.5%) and it was more toxic than leached-leaves extract (43%); however, toxicity of unleached-leaves extracts was slightly lower (90.5%). For organic extracts, the three fractions of leaves and flowers were more toxic; thistle was more sensitive especially to chloroform and methanol fractions of various organs. The two organs residues incorporation caused (at 2.5g kg-1) an average reduction between 34 and 100% for root and shoot length of target species. Irrigating soil with leaves and flowers aqueous extracts decreased seedlings length by 100% for peganum and 82% for thistle shoot. Results show that I. viscosa allelopathic potential seems to be attributed mainly to leaf leachate, which indicates the facility of providing this product and its use in irrigation for sustainable weed management. [ABSTRACT FROM AUTHOR]