Pablo Anselmo García

Universidad de Salamanca

When new antitumor therapy drugs are discovered, it is essential to address new target molecules from the point of view of chemical structure and to carry out efficient and systematic evaluation. In the case of natural products and derived compounds, it is of special importance to investigate chemomodulation to further explore antitumoral pharmacol...

Background The genus Cytinus, recognised as one of the most enigmatic in the plant kingdom, has garnered attention for its bioactive potential, particularly its skin anti-ageing properties. Despite this recognition, much remains to be accomplished regarding deciphering and isolating its most active compounds. Hypothesis This study aimed to identif...

Podophyllotoxin, a cyclolignan natural product, has been the object of extensive chemomodulation to obtain better chemotherapeutic agents. Among the obtained podophyllotoxin derivatives, podophyllic aldehyde showed very interesting potency and selectivity against several tumoral cell lines, so it became our lead compound for further modifications,...

Podophyllotoxin is a naturally occurring cyclolignan isolated from rhizomes of Podophyllum sp. In the clinic, it is used mainly as an antiviral; however, its antitumor activity is even more interesting. While podophyllotoxin possesses severe side effects that limit its development as an anticancer agent, nevertheless, it has become a good lead comp...

New lignohydroquinone conjugates (L-HQs) were designed and synthesized using the hybridization strategy, and evaluated as cytotoxics against several cancer cell lines. The L-HQs were obtained from the natural product podophyllotoxin and some semisynthetic terpenylnaphthohydroquinones, prepared from natural terpenoids. Both entities of the conjugate...

Cytinus hypocistis (L.) L. is a comestible holoparasite with great potential for cosmeceutical application. Although its high tannin content has been associated with its bioactive and inhibitory enzyme properties, this is the first report establishing a relationship between parasite and host (Halimium lasianthum (Lam.) Greuter) phenolic profile and...

Tannins are a class of phenolic compounds commonly found in plants and studied for their bioactive and inhibitory enzyme properties. Cytinus hypocistis (L.) L. is a wild edible parasitic plant whose biological properties have been correlated with its high tannin content. Thus, studying the extraction of tannins from C. hypocistis will give comprehe...

Terpenylquinones are mixed biogenesis primary or secondary metabolites widespread in Nature with many biological activities, including the antineoplastic cytotoxicity, that have inspired this work. Here, we present a cytotoxic structure-activity relationship of several diterpenylhydroquinone (DTHQ) derivatives, obtained from the natural labdane dit...

Natural products are the ideal basis for the design of novel efficient molecular entities. Podophyllotoxin, a naturally occurring cyclolignan, is an example of natural product which displays a high versatility from a biological activity point of view. Based on its unique chemical structure, different derivatives have been synthesized presenting the...

Cytinus hypocistis whole plant and its three different parts (petals, stalks, and nectar) were chemically characterised and their biological properties evaluated. A total of 17 phenolic compounds were identified, being galloyl-bis-HHDP-glucose the most abundant. All the tested extracts showed high antioxidant capacity, with the petals exhibiting th...

Leishmania is the aethiological agent responsible for the visceral leishmaniasis, a serious parasite-borne disease widely spread all over the World. The emergence of resistant strains makes classical treatments less effective; therefore, new and better drugs are necessary. Naphthoquinones are interesting compounds for which many pharmacological pro...

Quinones are secondary metabolites of higher plants associated with many biological activities, including antiviral effects and cytotoxicity. In this study, the anti-herpetic and anti-dengue evaluation of 27 terpenyl-1,4-naphthoquinone (NQ), 1,4-anthraquinone (AQ) and heterocycle-fused quinone (HetQ) derivatives was done in vitro against Human Herp...

The habit of eating wild plants in Europe is often associated with times of famine; an example of such is the nectar of Cytinus hypocistis (L.) L., a parasitic plant. To the authors’ best knowledge, there are no studies on its nutritional and chemical composition; thus, the whole C. hypocistis (L.) L. subsp. macranthus Wettst. plant (CH) and its ne...

Eugenia umbelliflora is a member of Myrtaceae family, with antimicrobial and anti-leishmanial properties related to the presence of phloroglucinol derivatives in its extracts. This study describe the isolation and structure elucidation of a sesquiterpenyl phloroglucinol (eugenial E), that is described here for the first time. Eugenial E (5) was iso...

Plants are considered among the main sources of biologically active chemicals. The species Solidago chilensis Meyen, Asteraceae, is native to the southern parts of South America, where the aerial parts of the plant are commonly used for the treatment of inflammatory conditions. However, the effects of S. chilensis on human cancer cells remain to be...

The sea is a rich source of biological active compounds, among which terpenyl-quinones/hydroquinones constitute a family of secondary metabolites with diverse pharmacological properties. The chemical diversity and bioactivity of those isolated from marine organisms in the last 10 years are summarized in this review. Aspects related to synthetic app...

A new family of molecular hybrids, between cyclolignans related to podophyllic aldehyde and several diterpenylnaphthohydroquinones (DNHQ), was prepared and its biological activity evaluated in several human solid tumor cell lines, which are representatives of the most prevalence solid tumors in Western world. Both, cyclolignan and quinone fragments...

Marine secondary metabolites with a purine motif in their structure are presented in this review. The alkylpurines are grouped according to the size of the alkyl substituents and their location on the purine ring. Aspects related to the marine source, chemical structure and biological properties are considered together with synthetic approaches tow...

Leishmania microtubules play an important role not only in cell division, but also in keeping the shape of the parasite and motility of its free-living stages. Microtubules result from the self-assembly of alpha and beta tubulins, two phylogenetically conserved and very abundant eukaryotic proteins in kinetoplastids. The colchicine binding domain h...

The cobalt crust fungus Terana coerulea (Phanerochaetaceae family) was selected for a bio-guided study after an ethnobotanical survey at the Irati's Forest (Navarra, Spain) for its local use as antibiotic. Six extracts of increasing polarity, from hexane to hot water, were obtained from powdered dry fungi and tested for cytotoxicity against four hu...

The chemical composition and bioactive properties of two plants (Calendula officinalis L. and Mentha cervina L.) were studied. Their nutritional value revealed a high content of carbohydrates and low fat levels, and very similar energy values. However, they presented different profiles in phenolic compounds and fatty acids; C. officinalis presented...

Several new terpenylpurine derivatives were prepared through alkylation of different purines with halogenated reagents derived from natural terpenoids, commercially available or isolated from cones of C. sempervirens L. and further transformed into appropriate alkylated agents. Alkylation of the purines gave mixtures of 9- and 7-alkylpurines, being...

This paper reports on the syntheses and spectrometric characterisation of eleven novel ent-kaurane diterpenoids, including a complete set of (1)H, (13)C NMR and crystallographic data for two novel ent-kaurane diepoxides. Moreover, the antineoplastic cytotoxicity for kaurenoic acid and the majority of ent-kaurane derivatives were assessed in vitro a...

A new family of hybrids between cyclolignans related to podophyllic aldehyde, a non-lactonic cyclolignan, and purines were prepared and evaluated against several human tumour cell lines. Both fragments, cyclolignan and purine, were linked through aliphatic and aromatic chains. The influence on the cytotoxicity of the purine substitution and the nat...

Two regioisomeric meroterpenoids, Eugenial A and B, have been isolated from the fruits of Eugenia multiflora and their structures established on the basis of NMR evidences. They possess a phloroglucinol-monoterpene structure similar to the euglobals occurring in the sister genus Eucaliptus. A simple method to distinguish between regioisomeric pairs...

A recent reinvestigation of aerial parts of Wedelia paludosa D.C. is described and reports, for the first time, the isolation of iso-kaurenoic acid from this species.

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Several series of nonlactonic podophyllic aldehyde analogues were prepared and evaluated against several human tumor cell lines. They had different combinations of aldehyde, imine, amine, ester, and amide functions at C-9 and C-9' of the cyclolignan skeleton. All the compounds synthesized showed cytotoxicity levels in the microM range and below. Wi...

Prevention methods to avoid transmission of pathogens, including HIV, are crucial in the control of infectious diseases, not only to block epidemic spread but to avoid long-term treatments leading to emergence of resistances and drug associated side effects. Together with vaccine development, the discovery of new virucidal agents represents a resea...

From a partially degraded Diels–Alder adduct of α-myrcene and 1,4-benzoquinone, several model compounds belonging to a new series of 1,4-naphthohydroquinone derivatives have been prepared. Phenyl, pyridyl, imidazolyl and some nucleic base mimic heterocycles have been attached to the naphthohydroquinone system through linkers of different size and t...

This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kaurane di...

This paper presents a review on kaurane diterpenes and their glycoside derivatives, covering aspects of their occurrence, biological activities and the synthesis of these natural products and their analogues. First, it shows and classifies diterpenes, in accordance with the already established structural criteria in the literature. Then, kauranedit...

A series of podophyllotoxin and podophyllic aldehyde derivatives, lacking the lactone ring and oxidized at C-9 position, has been prepared. The functionalities considered at C-9 were carboxylic acids and several derivatives such as esters, amides, nitriles or anhydrides. The synthesized compounds were cytotoxic at the micromolar level, though less...

The title compound, C21H32O3, was prepared by standard epoxi­dation of kaurenoic acid methyl ester. Its crystal structure confirms unequivocally the ent-16β epoxide configuration.

New oxidized ent-kaurane and ent-norkaurane derivatives were synthezised starting from kaurenoic acid. The spectroscopic characterization of all compounds is reported.

A new procedure to obtain anthracene-1,4-diones from p-benzoquinones and myrcene, in the presence of acids, is described. The cycloaddition reaction between α-myrcene and p-benzoquinones, followed by oxidation, led to 1,4-naphthoquinones or 1,4-anthraquinones depending upon whether the Lewis acid used in the Diels-Alder reaction, was present or abs...

In the crystal structure of the title compound, C21H34O3, mol­ecules are linked to each other by intermolecular O—H⋯O hydrogen bonds, involving the ester carbonyl group and the hydroxyl group.

Several podophyllotoxin derivatives modified in the A, B, C, D and E rings were prepared from podophyllotoxin and methyl isoxazopodophyllic acid and evaluated for their cytotoxicity on several neoplastic cell lines. Chemical transformations performed on these compounds have yielded derivatives more potent and more selective that the parent compound...

Podophyllotoxin and some of its derivatives are cyclolignans currently used for removing warts and in the clinical treatment of malign neoplasms. As such, they have been an objective of the scientific community for decades, in the search for more potent and more selective anticancer agents. Our interest in the chemoinduction of drug selectivity led...

Lignans are widely distributed in the plant kingdom, and display a variety of biological activities which have attracted the attention of the scientific community for decades. Several representative compounds of the cyclolignan class, such as podophyllotoxin and its semisynthetic derivative, etoposide, are currently used for the clinical treatment...

The cyclolignan family of natural products includes compounds with important antineoplastic and antiviral properties such as podophyllotoxin and two of their semisynthetic derivatives, etoposide and teniposide. The latter are included in a wide variety of cancer chemotherapy protocols. Due to these biological activities, cyclolignans have been the...

Several aldehydes related to methyl 9-deoxy-9-oxo-alpha-apopicropodophyllate, a selective antitumour agent against the HT-29 colon carcinoma, have been prepared and evaluated for their cytotoxic activities on four neoplastic cell lines (P-388, A-549, HT-29 and MEL-28). All of them lacked the lactone ring but maintained their cytotoxicity at, or und...

Several cyclolignans lacking of the lactone moiety can easily be prepared from naturally occurring lignans such as podophyllotoxin and deoxypodophyllotoxin by simple chemical transformations. Their cytotoxicity has been studied in four tumoral cell lines. Most of the compounds show similar effects in all the neoplastic systems tested, except the al...

13C NMR assignments are provided for 45 7- and/or 9-aza-substituted naphthalenecyclolignans. © 1997 John Wiley & Sons, Ltd.

Several derivatives of podophyllotoxin, lacking the lactone moiety and with nitrogen substituents at C-7 or C-9, have been prepared. They have been evaluated for their cytotoxic activity in P-388, A-549, HT-29 and MEL-28 culture cells. Some of them show a highly selective cytotoxicity towards HT-29 human colon carcinoma.