Lancea tibetica as the Tibetan herb: A review of its phytochemistry and pharmacology

This review, based on nearly 25 literary sources, discusses the chemical nature and biological effects of the whole plant of Lancea tibetica Hook. f. et Thoms (Scrophulariaceae). Several types of chemical constituents have been isolated from Lancea tibetica (LT) including 34 phenolpropanoids (16 lignans, 5 neolignans, 5 nonanones, 4 phenylpropanoid glycosides, and 4 propanediols), 9 flavones, 6 triterpenoids, and 11 amino acids. Various extracts and individual compounds derived from this species have been determined to possess a variety of pharmacological effects, such as anti-tumour and antioxidant functions. The results of data analysis on the chemical and pharmacological characteristics of LT support the view that this plant has many therapeutic properties, suggesting its potential as an effective herbal remedy. Finally, suggestions for further avenues of research on the chemical and pharmacological properties of LT and ways in which to further exploit LT are presented in this review.     

Tylophorinicine,a phenanthroindolizidine alkaloid from tylophora asthmatica and pergularia pallida

Tylophorinicine, a minor alkaloid isolated from the roots of Tylophora asthmatica and Pergularia pallida has been characterized as 14-hydroxytylophorine from physical and chemical evidence.     

Thermally induced chemical artifacts in lichens

Unsuspected thermal degradation of secondary products in lichens prior to chemical study, although probably uncommon, can lead to mistaken conclusions and taxonomic error. Thermally induced artifacts were found in the chemistries of Hypotrachyna partita from a site of volcanic activity in Costa Rica and in the type of H. prolongata from Haiti that had been dried for the herbarium with heat. In the Southern Appalachian Mountains normal material of H. prolongata has been considered a chemically different species. Thermal stability of secondary products may be an important factor in the chemical evolution of lichens inhabiting extreme environments.     

Florigenic Acid from fungal culture

The extraction procedures which have been successfully employed in the preparation of a florigenic principle from the tissues of Xanthium, are applicable to the derivation of an entity of similar activity from Calonectria culture. The Xanthium principle is acedic, with pK_a values characteristic of a carboxylic acid (6). Although definitive chemical comparisons have not been completed, the extraction and solvent partition procedures that have been applicable to the extraction of the active entity from higher plant tissues have yielded florigenic preparations from fungal culture. The chemical principle from higher plant tissue may be the same or similar to the florigenic agent of Calonectria.

The many responses of higher plants to growth regulators produced by micro-organisms are well known. The presence of a flower-producing principle from Calonectria (Fusarium) rigidiuscula parallels closely the pattern exhibited by those fungal species capable of the production of auxin and gibberellins.

     

New diterpenes from Porella perrottetiana

Perrottetianal A and perrottetianal B, two new diterpene dialdehydes and a new ent-labdane-type diterpene diol have been isolated from the liverwort Porella perrottetiana and their structures have been elucidated by the chemical and spectral evidence.     

Sesquiterpene lactones,waxes and volatile compounds from Artemisia herba-alba subspecies Valentina

The structures of two sesquiterpene lactones isolated from Artemisia herba-alba subsp. valentina have been determined by spectroscopic methods. One of these was dihydroreynosin, the other was a new compound assigned the name torrentin. The chemical compositions of a wax and a hydrocarbon fraction from the essential oil have also been investigated.     

Aquillochin,a coumarinolignan from Aquilaria agallocha

Aquillochin, isolated from the whole plant of Aquilaria agallocha, has been shown to be a coumarinolignan, and a structure has been proposed on the basis of chemical and physical studies.     

Novel nor-harmal alkaloid from Adhatoda vasica

A novel alkaloid and a galactoside isolated from the roots of Adhatoda vasica have been characterized as 9-acetamido-3,4-dihydropyrido-(3,4-b)-indole and O-ethyl-α-D-galactoside respectively by chemical and spectroscopic methods. In addition sitosterol β-D-glucoside, D-galactose and deoxyvasicinone have also been isolated from the roots of this plant.     

Heliangolides from Leucanthemopsis pulverulenta

The structure of hispanolide (4,5-cis-3-oxogermacranolide) and three other related germacranolides, isolated from Leucanthemopsis pulverulenta, have been established by a series of chemical transformations and spectral data.     

Aristoloside,an aristolochic acid derivative from stems of Aristolochia manshuriensis

Aristoloside, a new companion aristolochic acid derivative isolated from stems of Aristolochia manshuriensis has been shown to be 6-O-β-d-glucopyranoside of aristolochic acid-D on chemical and physicochemical evidence. Three known acids, aristolochic acids I, IV (both as their corresponding methyl esters), and -D have also been characterized from stems of the plant.     

Mixtecacin,a prenylated flavanone and oaxacacin its chalcone from the roots of Tephrosia woodii

From the roots of Tephrosia woodii, a new Mexican Tephrosia species, a new prenylated flavanone, oaxacacin, and its chalcone, mixtecacin, have been isolated and their structures elucidated from their chemical properties and spectral data.     

Deuterium isotope effects in carbohydrates revisited. Cryoprobe studies of the anomerization and NH to ND deuterium isotope induced 13C NMR chemical shifts of acetamidodeoxy and aminodeoxy sugars

Complete ¹H and ¹³C NMR chemical shift assignments have been generated from a series of acetamidodeoxy and aminodeoxy sugar derivatives. For free sugars, the enhanced sensitivity of an NMR cryoprobe allowed simple 1D and 2D NMR spectra to be obtained from essentially single anomers, before significant mutarotation had occurred. The NMR assignments have been used to characterize deuterium isotope effects on ¹³C chemical shifts measured under conditions of slow NH to ND exchange in single solutions. Within a range of 0 to −0.138 ppm, β, γ, δ, and ζ deuterium isotope effects have been observed, thus providing additional reference data for assignment of the ¹³C NMR spectra of nitrogenous saccharides.     

Diterpenoids from sideritis pusilla subsp. flavovirens

Several new 14-hydroxybeyerene acetates have been isolated from the aerial parts of Sideritis pusilla subsp. flavovirens. In addition, an ent-kaur-15-ene (siderol) and a new ent-7α, 18-dihydroxybeyer-15-ene (flavovirol) have been obtained from the same source. The structures of these new acetates have been established by chemical and spectroscopic means and the structure of flavovirol has been confirmed by ¹³C NMR.     

Sesquiterpenes from Pityrogramma calomelanos

Pterosin Z has been obtained from Pityrogramma calomelanos. A related compound calomelanolactone has also been isolated and its structure assigned from chemical, spectral, biogenetic and X-ray evidence.     

Minor xanthones of Garcinia mangostana

Two new trioxygenated xanthones with a 3,3-dimethyl allyl side chain have been isolated from the fruit hulls of Garcinia mangostana. The structures were established from spectral and chemical data.     

Glycolone,a quinolone alkaloid from Glycosmis pentaphylla

Glycolone, a quinolone alkaloid has been isolated from the leaves of Glycosmis pentaphylla. The structure of the compound has been established as 4,8-dimethoxy-3-(3-methyl but-2-enyl)-2-quinolone from physical and chemical evidences.     

A new alkamide from Piper sylvaticum

Sylvamide, a new amide derivative, has been isolated from the petrol extract of the seeds of Piper sylvaticum (Roxb.). From spectral and chemical s     

Chemical intermediates in dopamine oxidation by tyrosinase,and kinetic studies of the process

A minor pathway for dopamine oxidation to dopaminochrome, by tyrosinase, is proposed. Characterization of intermediates in this oxidative reaction and stoichiometric determination have both been undertaken. After oxidizing dopamine with mushroom tyrosinase or sodium periodate in a pH range from 6.0 to 7.0, it was spectrophotometrically possible to detect o-dopaminoquinone-H⁺ as the first intermediate in this pathway. The steps for dopamine transformation to dopaminochrome are as follows: dopamine → o-dopaminequinone-H⁺ → o-dopaminequinone → leuko-dopaminochrome → dopaminochrome. No participation of oxygen was detected in the conversion of leukodopaminochrome to dopaminochrome. Scanning spectroscopy and graphical analysis of the obtained spectra also verified that dopaminequinone-H⁺ was transformed into aminochrome in a constant ratio. The stoichiometry equation for this conversion is 2 o-dopaminequinone-H⁺ → dopamine + dopaminochrome. The pathway for dopamine oxidation to dopaminochrome by tyrosinase has been studied as a system of various chemical reactions coupled to an enzymatic reaction. A theoretical and experimental kinetic approach is proposed for such a system; this type of mechanism has been named “Enzymatic-chemical-chemical” (E_ZCC). Rate constants for the implied chemical steps at different pH and temperature values have been evaluated from the measurement of the lag period arising from the accumulation of dopaminochrome that took place when dopamine was oxidized at acid pH. The thermodynamic activation parameters of the chemical steps, the deprotonation of dopaminequinone-H⁺ to dopaminequinone, and the internal cyclization of dopaminequinone to leukodopaminochrome have been calculated.     

Enzymatic synthesis of apigenin glucosides by glucosyltransferase (YjiC) from Bacillus licheniformis DSM 13

Apigenin, a member of the flavone subclass of flavonoids, has long been considered to have various biological activities. Its glucosides, in particular, have been reported to have higher water solubility, increased chemical stability, and enhanced biological activities. Here, the synthesis of apigenin glucosides by the in vitro glucosylation reaction was successfully performed using a UDP-glucosyltransferase YjiC, from Bacillus licheniformis DSM 13. The glucosylation has been confirmed at the phenolic groups of C-4′ and C-7 positions ensuing apigenin 4′-O-glucoside, apigenin 7-O-glucoside and apigenin 4′,7-O-diglucoside as the products leaving the C-5 position unglucosylated. The position of glucosylation and the chemical structures of glucosides were elucidated by liquid chromatography/mass spectroscopy and nuclear magnetic resonance spectroscopy. The parameters such as pH, UDP glucose concentration and time of incubation were also analyzed during this study.     

Hedychenone: A furanoid diterpene from Hedychium spicatum

The structure of hedychenone, a furanoid diterpene, isolated from the rhizomes of Hedychium spicatum has been deduced on the basis of spectroscopic and chemical evidence.