Anti-tumoral activity of native compound morelloflavone in glioma

Garcinia kola: a critical review on chemistry and pharmacology of an important West African medicinal plant

Garcinia kola Heckel (Clusiaceae) is a tree indigenous to West and Central Africa. All plant parts, but especially the seeds, are of value in local folklore medicine. Garcinia kola is used in treatment of numerous diseases, including gastric disorders, bronchial diseases, fever, malaria and is used to induce a stimulating and aphrodisiac effect. The plant is now attracting considerable interest as a possible source of pharmaceutically important drugs. Several different classes of compounds such as biflavonoids, benzophenones, benzofurans, benzopyran, vitamin E derivatives, xanthones, and phytosterols, have been isolated from G. kola, of which many appears to be found only in this species, such as garcinianin (found in seeds and roots), kolanone (fruit pulp, seeds, roots), gakolanone (stem bark), garcinoic acid, garcinal (both in seeds), garcifuran A and B, and garcipyran (all in roots). They showed a wide range of pharmacological activities (e.g. analgesic, anticancer, antidiabetic, anti-inflammatory, antimalarial, antimicrobial, hepatoprotective and neuroprotective effects), though this has only been confirmed in animal models. Kolaviron is the most studied compound and is perceived by many studies as the active principle of G. kola. However, its research is associated with significant flaws (e.g. too high doses tested, inappropriate positive control). Garcinol has been tested under better conditions and is perhaps showing more promising results and should attract deeper research interest (especially in the area of anticancer, antimicrobial, and neuroprotective activity). Human clinical trials and mechanism-of-action studies must be carried out to verify whether any of the compounds present in G. kola may be used as a lead in the drug development.

Camboginol and Morelloflavone from Garcinia dulcis (Roxb.) Kurz Flower Extract Promote Autophagic Cell Death against Human Glioblastoma Cells through Endoplasmic Reticulum Stress

Garcinia dulcis is a tropical plant native to Southeast Asia that is traditionally used as a folk remedy to cure several pathological symptoms. Camboginol and morelloflavone have been revealed by previous studies as the principal bioactive compounds from the flower extract of G. dulcis. The disease-preventing properties of camboginol or morelloflavone, including anti-cancer, from various parts of G. dulcis have been revealed by recent studies. Glioblastoma is the aggressive malignant stage of brain cancer and suffers from chemotherapeutic resistance. This study aimed to test the anti-cancer effect of G. dulcis flower extract against the proliferation of A172 human glioblastoma cells. The extract had cytotoxic activity and promoted cell cycle arrest at the S and G2/M phases. Autophagic cell death was promoted by cytotoxic concentrations of the extract, as observed by enhancing autophagic flux and the expression of autophagic markers. Autophagic cell death induced by the extract might be associated with endoplasmic reticulum (ER) stress. Conclusively, it was indicated by this study that the extract from the flower of G. dulcis had a protective effect against the proliferation of A172 human glioblastoma cells through the induction of ER stress-mediated cytotoxic autophagy.

Phytochemicals and Biological Activities of Garcinia atroviridis: A Critical Review

Garcinia atriviridis Griff ex T. Anders (G. atroviridis) is one of the well-known species of the genus Garicinia that is native to Thailand, Myanmar, Peninsular Malaysia, and India. G. atroviridis is a perennial medium-sized tree that has a wide range of values, from food to medicinal use. Different parts of G. atroviridis are a great source of bioactive substances that have a positive impact on health. The extracts or bioactive constituents from G. atroviridis have demonstrated various therapeutic functions, including antioxidant, antimicrobial, anticancer, anti-inflammatory, antihyperlipidemic, and anti-diabetic. In this paper, we provide a critical review of G. atroviridis and its bioactive constituents in the prevention and treatment of different diseases, which will provide new insight to explore its putative domains of research.

Insights into the Molecular Mechanisms of Eg5 Inhibition by (+)-Morelloflavone

(+)-Morelloflavone (MF) is an antitumor biflavonoid that is found in the Garcinia species. Recently, we reported MF as a novel inhibitor of ATPase and microtubules-gliding activities of the kinesin spindle protein (Eg5) in vitro. Herein, we provide dynamical insights into the inhibitory mechanisms of MF against Eg5, which involves binding of the inhibitor to the loop5/α2/α3 allosteric pocket. Molecular dynamics simulations were carried out for 100 ns on eight complexes: Eg5-Adenosine diphosphate (Eg5-ADP), Eg5-ADP-S-trityl-l-cysteine (Eg5-ADP-STLC), Eg5-ADP-ispinesib, Eg5-ADP-MF, Eg5-Adenosine triphosphate (Eg5-ATP), Eg5-ATP-STLC, Eg5-ATP-ispinesib, and Eg5-ATP-MF complexes. Structural and energetic analyses were done using Umbrella sampling, Molecular Mechanics Poisson–Boltzmann Surface Area (MM/PBSA) method, GROMACS analysis toolkit, and virtual molecular dynamics (VMD) utilities. The results were compared with those of the known Eg5 inhibitors; ispinesib, and STLC. Our data strongly support a stable Eg5-MF complex, with significantly low binding energy and reduced flexibility of Eg5 in some regions, including loop5 and switch I. Furthermore, the loop5 Trp127 was trapped in a downward position to keep the allosteric pocket of Eg5 in the so-called “closed conformation”, comparable to observations for STLC. Altered structural conformations were also visible within various regions of Eg5, including switch I, switch II, α2/α3 helices, and the tubulin-binding region, indicating that MF might induce modifications in the Eg5 structure to compromise its ATP/ADP binding and conversion process as well as its interaction with microtubules. The described mechanisms are crucial for understanding Eg5 inhibition by MF.

Potential Anticancer Agents Characterized from Selected Tropical Plants

Higher plants are well known for their value in affording clinically useful anticancer agents, with such compounds acting against cancer cells by a range of mechanisms of action. There remains a strong interest in the discovery and development of plant secondary metabolites as additional cancer chemotherapeutic lead compounds. In the present review, progress on the discovery of plant-derived compounds of the biflavonoid, lignan, sesquiterpene, steroid, and xanthone structural types is presented. Several potential anticancer leads of these types have been characterized from tropical plants collected in three countries as part of our ongoing collaborative multi-institutional project. Preliminary structure-activity relationships and work on in vivo testing and cellular mechanisms of action are also discussed. In addition, the relevant work reported by other groups on the same compound classes is included herein.

Salts Influence Cathechins and Flavonoids Encapsulation in Liposomes: A Molecular Dynamics Investigation

Cathechins and flavonoids are responsible of numerous health benefits. Two of the most representatives' compounds for their antioxidant and therapeutic effects are Epigallocatechin 3-Gallate (EGCG), from green tea extracts, and morelloflavone (MF), from Garcinia dulcis. Here we explore, by atomistic Molecular Dynamics simulations, how EGCG and MF interact with lipid bilayers and we show the salts' influence on their encapsulation degree in neutral liposomes. As a result, we found out that EGCGs naturally bind to the hydrophilic regions of phospholipids, positioning themselves mostly at the interface between water and lipid phases. The presence of a salt clearly influences the EGCG molecules' absorption and the total effect depends strongly on the salt nature and concentration. Beside, for MF, we observed a high stability of the intermolecular MFs aggregates in water that strongly penalizes the flavonoid's interaction with the lipid polar heads. However, salts can influence MF's liposomal penetration, even if they are not able to promote completely its absorption inside the bilayer. For both compounds, the increase of penetration is more marked in presence of magnesium chloride, whilst calcium chloride showed the opposite effect.