Plant anticancer agents. IX. Constituents of Hyptis tomentosa

Bioassay-Guided Discovery of Potential Partial Extracts with Cytotoxic Effects on Liver Cancer Cells from Vietnamese Medicinal Herbs

Hepatocellular carcinoma (HCC) is the most frequent type of primary liver cancer and is the leading cause of cancer mortality in Vietnam. Our study aims to discover the partial extracts with the potential cytotoxic effects on HCC cells from the different parts of 24 Vietnamese medicinal plants traditionally used in liver cancer treatment. Out of 52 crude methanol extracts, we found that Luvunga scandens leaves, Hyptis suaveolens roots, and Solanum torvum leaves showed the notable cytotoxic effects against HCC cells. After that, we carried out partial extract of the three methanol extracts with ethyl acetate, water, n-hexane, and 90% methanol. The cytotoxic activity on Huh-7 HCC cells, antioxidant capacity, and total flavonoids content (TFC) of each partial extraction were determined. Methanol, ethyl acetate, and 90% methanol extracts showed moderate to strong cytotoxicity activity against Huh-7 HCC cells. Notably, the ethyl acetate and 90% methanol extract from H. suaveolens roots with high TFC values and strong antioxidant capacity could be promising sources of novel therapeutic modalities for HCC treatment. For the leaves of L. scandens and S. torvum, the ethyl acetate extract showed high TFC value and promising anti-HCC activity, therefore recommended further studies.

Subtribe Hyptidinae (Lamiaceae): A promising source of bioactive metabolites

ETHNOPHARMACOLOGICAL RELEVANCE

The subtribe Hyptidinae contains approximately 400 accepted species distributed in 19 genera (Hyptis, Eriope, Condea, Cantinoa, Mesosphaerum, Cyanocephalus, Hypenia, Hyptidendron, Oocephalus, Medusantha, Gymneia, Marsypianthes, Leptohyptis, Martianthus, Asterohyptis, Eplingiella, Physominthe, Eriopidion and Rhaphiodon). This is the Lamiaceae clade with the largest number of species in Brazil and high rates of endemism. Some species have been used in different parts of the world mainly as insecticides/pest repellents, wound healing and pain-relief agents, as well as for the treatment of respiratory and gastrointestinal disorders.

AIM OF THE REVIEW

This review aims to discuss the current status concerning the taxonomy, ethnobotanical uses, phytochemistry and biological properties of species which compose the subtribe Hyptidinae.

MATERIALS AND METHODS

The available information was collected from scientific databases (ScienceDirect, Pubmed, Web of Science, Scopus, Google Scholar, ChemSpider, SciFinder ACS Publications, Wiley Online Library), as well as other literature sources (e.g. books, theses).

RESULTS

The phytochemical investigations of plants of this subtribe have led to the identification of almost 300 chemical constituents of different classes such as diterpenes, triterpenes, lignans, α-pyrones, flavonoids, phenolic acids and monoterpenes and sesquiterpenes, as components of essential oils. Extracts, essential oils and isolated compounds showed a series of biological activities such as insecticide/repellent, antimicrobial and antinociceptive, justifying some of the popular uses of the plants. In addition, a very relevant fact is that several species produce podophyllotoxin and related lignans.

CONCLUSION

Several species of Hyptidinae are used in folk medicine for treating many diseases but only a small fraction of the species has been explored and most of the traditional uses have not been validated by current investigations. In addition, the species of the subtribe appear to be very promising as alternative sources of podophyllotoxin-like lignans which are the lead compounds for the semi-synthesis of teniposide and etoposide, important antineoplastic agents. Thus, there is a wide-open door for future studies, both to support the popular uses of the plants and to find new biologically active compounds in this large number of species not yet explored.

Phytochemical profiles, and antimicrobial and antioxidant activities of greater galangal [Alpinia galanga (Linn.) Swartz.] flowers

Previous studies of galangal (Alpinia galanga) have focussed mostly on rhizomes but seldom on flowers. A comprehensive look at galangal flowers could reveal additional benefits. The chemical composition of galangal flowers was significantly (p < 0.05) different from that of galangal rhizome. Pentadecane and α-humulene were identified as major compounds of galangal flower essential oil. 1'-acetoxyeugenol acetate was identified as the highest compound in flowers and exhibited the strongest antimicrobial activity among all fractions, with MIC₅₀ values of 34 μg/ml against Staphylococcus aureus and 68 μg/ml against Listeria monocytogenes. Galangal flowers had a 3-fold higher total phenols content than had rhizomes (10.5 vs. 3.33 mg GAE/g powder). The antioxidant activities of different flower fractions varied from 2 to 4.45 mmol  trolox/g phenolics. These findings suggest that antimicrobial and antioxidant agents extracted from galangal flowers could potentially be utilized as natural food preservatives or as therapeutic agents.

The utility of metabolomics in natural product and biomarker characterization

BACKGROUND

Metabolomics is a well-established rapidly developing research field involving quantitative and qualitative metabolite assessment within biological systems. Recent improvements in metabolomics technologies reveal the unequivocal value of metabolomics tools in natural products discovery, gene-function analysis, systems biology and diagnostic platforms.

SCOPE OF REVIEW

We review here some of the prominent metabolomics methodologies employed in data acquisition and analysis of natural products and disease-related biomarkers.

MAJOR CONCLUSIONS

This review demonstrates that metabolomics represents a highly adaptable technology with diverse applications ranging from environmental toxicology to disease diagnosis. Metabolomic analysis is shown to provide a unique snapshot of the functional genetic status of an organism by examining its biochemical profile, with relevance toward resolving phylogenetic associations involving horizontal gene transfer and distinguishing subgroups of genera possessing high genetic homology, as well as an increasing role in both elucidating biosynthetic transformations of natural products and detecting preclinical biomarkers of numerous disease states.

GENERAL SIGNIFICANCE

This review expands the interest in multiplatform combinatorial metabolomic analysis. The applications reviewed range from phylogenetic assignment, biosynthetic transformations of natural products, and the detection of preclinical biomarkers.

The lignan, (-)-sesamin reveals cytotoxicity toward cancer cells: pharmacogenomic determination of genes associated with sensitivity or resistance

(-)-Sesamin is a lignan present in sesam oil and a number of medicinal plants. It exerts various pharmacological effects, such as prevention of hyperlipidemia, hypertension, and carcinogenesis. Moreover, (-)-sesamin has chemopreventive and anticancer activity in vitro and in vivo. Multidrug resistance (MDR) of tumors leads to fatal treatment outcome in many patients and novel drugs able to kill multidrug-resistant cells are urgently needed. P-glycoprotein (MDR1/ABCB1) is the best known ATP-binding cassette (ABC) drug transporter mediating MDR. ABCB5 is a close relative to ABCB1, which also mediates MDR. We found that the mRNA expressions of ABCB1 and ABCB5 were not related to the 50% inhibition concentrations (IC50) for (-)-sesamin in a panel of 55 cell lines of the National Cancer Institute, USA. Furthermore, (-)-sesamin inhibited ABCB1- or ABCB5-overexpressing cells with similar efficacy than their drug-sensitive parental counterparts. In addition to ABC transporter-mediated MDR, we attempted to identify other molecular determinants of (-)-sesamin resistance. For this reason, we performed COMPARE and hierarchical cluster analyses of the transcriptome-wide microarray-based mRNA expression of the NCI cell panel. Twenty-three genes were identified, whose mRNA expression correlated with the IC50 values for (-)-sesamin. These genes code for proteins of different biological functions, i.e. ribosomal proteins, components of the mitochondrial respiratory chain, proteins involved in RNA metabolism, protein biosynthesis, or glucose and fatty acid metabolism. Subjecting this set of genes to cluster analysis showed that the cell lines were assembled in the resulting dendrogram according to their responsiveness to (-)-sesamin. In conclusion, (-)-sesamin is not involved in MDR mediated by ABCB1 or ABCB5 and may be valuable to bypass chemoresistance of refractory tumors. The microarray expression profile, which predicted sensitivity or resistance of tumor cells to (-)-sesamin consisted of genes, which do not belong to the classical resistance mechanisms to established anticancer drugs.

Antitumor Activity of Leaves from Hyptis mutabilis (A. Rich.) Briq. (Lamiaceae) in Mice Bearing Tumor

The Hyptis genus has more than 400 species, many of them being used in folk medicine to treat several conditions. Some anticancer compounds have been isolated from plants of this genus, and for that reason we decided to investigate the potential in vivo antitumor activity of extracts of leaves of Hyptis mutabilis with different polarities (hexane, methanol, water, and hot water) against two mice tumors: sarcoma 180 and Ehrlich solid tumor. Phytochemical analysis revealed strong presence of steroids, saponins, flavonoids (mainly dihydroflavanols), and catechins. Acute toxicity was perfomed according to the up-and-down method showing LD50 values ranging from 100 up to 2500 mg/kg. Antitumor activity was investigated using 10% of the LD50 for each extract. Methotrexate was used as positive control. Both aqueous extracts showed strong inhibition of tumor growth with values up to 70% of inhibition growth for sarcoma 180. Ehrlich solid tumor was only slight inhibited by hexane extract (38.6%). In conclusion, the aqueous extracts of H. mutabilis showed promising results against sarcoma 180 mice tumor.

Constituents of Calamintha ashei: Effects on Florida Sandhill Species

Chemical constituents of the perennial shrub Calamintha ashei have been characterized as part of our investigation of the allelopathic properties of this plant. Besides the known monoterpenes, (+)-evodone, (-)-calaminthone and (+)-desacetylcalaminthone, fresh aerial parts of C. ashei provided six new menthofurans, two new germacrane sesquiterpenes, and the six, known flavonoids: 5-desmethoxynobiletin, 5-hydroxy-6,7,8,4′-tetramethoxyflavone, 5,4′-dihydroxy-6,7,8,3′-tetra-methoxyflavone, thymonin, 5,4′-dihydroxy-6,7-dimethoxyflavone and 6-hydroxy-7,3′-dimethoxyluteolin. The structures of the new compounds were elucidated by spectroscopic methods and comparison of their 1H NMR spectra with those of structurally related compounds. The molecular structures of (+)-evodone, 5-desmethoxynobiletin (5-hydroxy-6,7,8,3′,4′-pentamethoxyflavone) and the triacetate of thymonin (7,8,3′-trimethoxy-5,6,4′-triacetoxyflavone), were determined by single crystal X-ray diffraction. Saturated aqueous solutions of menthofuran, (+)-evodone, (-)-calaminthone, (+)-desacetylcalaminthone, 4α,5β–diacetoxymenthofuran, as well as mixtures of (+)-evodone and (+)-desacetylcalaminthone inhibited the germination and root growth of Schizachyrium scoparium and Leptochloa dubia, two native Florida sandhill grasses, as well as Lactuca sativa. (+)-Evodone and (+)-desacetylcalaminthone were the most active. 5-Hydroxy-6,7,8,3′,4′-pentamethoxyflavone and 5,4′-dihydroxy-6,7,8,3′-tetramethoxyflavone and mixtures of the two flavonoids in aqueous as well as in saturated aqueous solutions of ursolic acid were tested on the same species, but showed no significant activity.

Selection methodology with scoring system: application to Mexican plants producing podophyllotoxin related lignans

As most anticancer drugs are derived from natural sources, the screening of local medicinal flora should be considered a primary step in the search for new sources for antineoplastic agents. In Mexico, more than 6000 medicinal plant species are used for the treatment of various diseases, including cancer. A multifactorial plant selection method, employing various criteria was designed and applied in order to select alternative sources of podophyllotoxin lignan analogues. For each criterion (chemotaxonomy, traditional medical uses and published scientific data), an arbitrary score system was ascribed to the species and the sum of these enabled us to compare potential candidates. The resulting selected plants were tested for cytotoxic activity and the compounds responsible for this activity were evaluated by liquid chromatography-mass spectroscopy (LC-MS). Around 50 species from the Mexican flora were initially considered. From these, six species were selected by referring to the results from the scoring system and these were then collected. Three extracts were evaluated as being highly cytotoxic against three different cancer cell lines. Finally, podophyllotoxin-like lignans could be identified by observing the fragmentation pattern on mass spectra, obtained from the LC-MS in two species: Linum scabrellum and Hyptis suaveolens.

Biological activities of crude plant extracts from Vitex trifolia L. (Verbenaceae)

Biological assays of Vitex trifolia L. organic extracts have shown relevant activities. Hexanic and dichloromethanic (DCM) extracts, when prepared from stems and foliage, have proved to be very toxic against several cancer cell lines in culture (SQC-1 UISO, OVCAR-5, HCT-15 COLADCAR, and KB). Also, an important antifeeding activity against the insect pest Spodoptera frugiperda (Lepidoptera: Noctuidae) was recorded. The hexanic extract from leaves completely inhibited the growth of the fungal plant pathogen Fusarium sp. within the first 2 days of the experiment, but dropped significantly at day 6 (15% inhibition). The potential of V. trifolia for several uses is discussed.

Excretion of the lignans enterolactone and enterodiol and of equol in omnivorous and vegetarian postmenopausal women and in women with breast cancer

Dietary studies and assays of urinary lignans in postmenopausal women showed that lignan excretion is significantly lower in urine of women with breast cancer than in normal omnivorous and vegetarian women and confirmed that there is a significant correlation between fibre intake and lignan excretion. It is suggested that the precursors of the human lignans enterolactone and enterodiol formed by the intestinal microflora are to be found in fibre-rich foods such as grains, nuts, and legumes. Excretion of equol, which has antioestrogenic properties, was similar in all groups studied and did not correlate with fibre intake, but occasional high values were found in some subjects.