Restoration of camptothecine production in attenuated endophytic fungus on re-inoculation into host plant and treatment with DNA methyltransferase inhibitor

Fungal endophytes inhabit living tissues of plants without any apparent symptoms and in many cases are known to produce secondary metabolites similar to those produced by their respective host plants. However on sub-culture, the endophytic fungi gradually attenuate their ability to produce the metabolites. Attenuation has been a major constraint in realizing the potential of endophytic fungi as an alternative source of plant secondary metabolites. In this study, we report attempts to restore camptothecine (CPT) production in attenuated endophytic fungi isolated from CPT producing plants, Nothapodytes nimmoniana and Miquelia dentata when they are passed through their host plant or plants that produce CPT and when treated with a DNA methyl transferase inhibitor. Attenuated endophytic fungi that traversed through their host tissue or plants capable of synthesizing CPT, produced significantly higher CPT compared to the attenuated fungi. Attenuated fungus cultured in the presence of 5-azacytidine, a DNA methyltransferase inhibitor, had an enhanced CPT content compared to untreated attenuated fungus. These results indicate that the attenuation of CPT production in endophytic fungi could in principle be reversed by eliciting some signals from plant tissue, most likely that which prevents the methylation or silencing of the genes responsible for CPT biosynthesis.

Ambient ionization mass spectrometry imaging of rohitukine, a chromone anti-cancer alkaloid, during seed development in Dysoxylum binectariferum Hook.f (Meliaceae)

Rohitukine, a chromone alkaloid, possesses anti-inflammatory, anti-cancer and immuno-modulatory properties. It has been reported from four species, belonging to the families, Meliaceae and Rubiaceae. Stem bark of Dysoxylum binectariferum (Meliaceae) accumulates the highest amount of rohitukine (3-7% by dry weight). In this study, we examine the spatial and temporal distribution of rohitukine and related compounds during various stages of seed development in D. binectariferum using desorption electrospray ionization mass spectrometry imaging (DESI MSI). Rohitukine (m/z 306.2) accumulation increased from early seed development to seed maturity stage. The spatial distribution of rohitukine was largely restricted to the cotyledonary tissue followed by the embryo and least in the seed coat. Besides rohitukine, rohitukine acetate (m/z 348.2) and glycosylated rohitukine (m/z 468.2) were also detected, both through mass fragmentation and exact mass analysis through Orbitrap mass spectrometry. These results indicate a dynamic pattern of chromane alkaloid accumulation through seed development in D. binectariferum.

Mud-packing frog: a novel breeding behaviour and parental care in a stream dwelling new species of Nyctibatrachus (Amphibia, Anura, Nyctibatrachidae)

Reproductive modes are diverse and unique in anurans. Selective pressures of evolution, ecology and environment are attributed to such diverse reproductive modes. Globally forty different reproductive modes in anurans have been described to date. The genus Nyctibatrachus has been recently revised and belongs to an ancient lineage of frog families in the Western Ghats of India. Species of this genus are known to exhibit mountain associated clade endemism and novel breeding behaviours. The purpose of this study is to present unique reproductive behaviour, oviposition and parental care in a new species Nyctibatrachus kumbara sp. nov. which is described in the paper. Nyctibatrachus kumbara sp. nov. is a medium sized stream dwelling frog. It is distinct from the congeners based on a suite of morphological characters and substantially divergent in DNA sequences of the mitochondrial 16S rRNA gene. Males exhibit parental care by mud packing the egg clutch. Such parental care has so far not been described from any other frog species worldwide. Besides this, we emphasize that three co-occurring congeneric species of Nyctibatrachus, namely N. jog, N. kempholeyensis and Nyctibatrachus kumbara sp. nov. from the study site differ in breeding behaviour, which could represent a case of reproductive character displacement. These three species are distinct in their size, call pattern, reproductive behaviour, maximum number of eggs in a clutch, oviposition and parental care, which was evident from the statistical analysis. The study throws light on the reproductive behaviour of Nyctibatrachus kumbara sp. nov. and associated species to understand the evolution and adaptation of reproductive modes of anurans in general, and Nyctibatrachus in particular from the Western Ghats.

Rohitukine, a chromone alkaloid and a precursor of flavopiridol, is produced by endophytic fungi isolated from Dysoxylum binectariferum Hook.f and Amoora rohituka (Roxb).Wight & Arn

Rohitukine, a chromone alkaloid, has gained considerable international attention in recent years because of its novel semi-synthetic derivative, flavopiridol and P-276-00. Both these molecules are in advanced stages of clinical development and trial for cancer treatment. Recently, flavopiridol was approved as an orphan drug for treatment of chronic lymphocytic leukemia cancer. The natural occurrence of rohitukine is restricted to only four plant species, Amoora rohituka and Dysoxylum binectariferum (both from the Meliaceae family) and from Schumanniophyton magnificum and Schumanniophyton problematicum (both from the Rubiaceae family). Recently, an endophytic fungi isolated from D. binectariferum was reported to produce rohitukine in culture. In this study, we report the production of rohitukine and its subsequent attenuation by endophytic fungi, Fusarium oxysporum (MTCC-11383), Fusarium oxysporum (MTCC-11384) and Fusarium solani (MTCC-11385), all isolated from D. binectariferum and Gibberella fujikuroi (MTCC-11382) isolated from Amoora rohituka. The fungal rohitukine which was analyzed by HPLC, LC-MS and LC-MS/MS was identical to reference rohitukine and that produced by the plant. The rohitukine content in the mycelial samples ranged from 192.78μg to 359.55μg100g(-1) of dry weight of and in broth it ranged from 14.10 to 71.90μg100ml(-1). In all the fungal cultures, the production declined from first to fourth sub-culture. Studies are underway to unravel the mechanism by which the fungi produce the host metabolite in culture.

Isolation of endophytic bacteria producing the anti-cancer alkaloid camptothecine from Miquelia dentata Bedd. (Icacinaceae)

Camptothecine (CPT), a quinoline alkaloid, is a potent inhibitor of eukaryotic topoisomerase I. Because of this activity, several semi-synthetic derivatives of CPT are in clinical use against ovarian and small lung cancers. Together with its derivatives, CPT is the third largest anti-cancer drug in the world market. CPT is produced by several plant species belonging to the Asterid clade. In the recent past, several studies have reported the production of CPT by endophytic fungal associates of some of these plant species. In this paper, we report the production of CPT by endophytic bacteria isolated from Miquelia dentata Bedd. (Icacinaceae). Besides CPT, the bacteria also produced 9-methoxy CPT (9-MeO-CPT), in culture, independent of the host tissue. The chemical nature of CPT and 9-MeO-CPT was determined by LC-MS and ESI-MS/MS analysis, and was shown to be similar to that produced by the host tissue. One of the bacterial isolates examined, showed indications of attenuation of CPT production through sub-culture. This is the first report of production of CPT by endophytic bacteria. The identity of the bacteria was ascertained by Gram staining and 16s rRNA sequencing. We discuss the possible mechanisms that might be involved in the synthesis of CPT by endophytic bacteria.

New plant sources of the anti-cancer alkaloid, camptothecine from the Icacinaceae taxa, India

In this study, the production of camptothecine and its derivatives, in thirteen species of the family Icacinaceae, namely, Apodytes dimidiata, Codiocarpus andamanicus, Gomphandra comosa, Gomphandra coriacea, Gomphandra polymorpha, Gomphandra tetrandra, Iodes cirrhosa, Iodes hookeriana, Miquelia dentata, Miquelia kleinii, Natsiatum herpeticum, Pyrenacantha volubilis and Sarcostigma kleinii is reported. Seeds of M. dentata were found to produce the highest content of camptothecine (1.0-1.4% by dry weight of seeds). Full scan LC-MS and ESI-MS/MS analysis of M. dentata revealed, besides camptothecine, a number of other derivatives, namely, 10-hydroxycamptothecine, 9-methoxycamptothecine, 20-deoxycamptothecine. Crude extract preparations of the seeds of M. dentata were effective against a breast cancer cell line (IC50=3.82 μg/ml for MDA MB273 cell lines) and two ovarian cancer cell lines (IC50=2.8 μg/ml for NCI/ADR-RES and 4.5 μg/ml for SKOV). These results are the first reports of camptothecine and its derivatives in these species and offer rich alternative plant sources for the anticancer compound, camptothecine.

Study on incidence of bleeding in hospitalized patients after antithrombotic therapy at a tertiary care hospital

OBJECTIVES

To monitor the different antithrombotic drug combinations, determine the incidence, magnitude of bleeding and the association of HAS-BLED risk scoring schema with the magnitude of bleeding as defined using TIMI bleeding criteria.

METHODS

A prospective observational study in a cohort of patients for a period of 8 months, at one of the tertiary care center-Krishna Institute of Medical Sciences, Hyderabad, was conducted. Consecutive patients were enrolled and followed from the date of admission till the adverse events are perceived/date of discharge. Pearson Correlation Statistics (Fisher's z Transformation) is applied to assess the association between HAS-BLED risk factors and the total risk score with bleeding criteria.

RESULTS

A total of 400 cases were collected during the 8-month study period, of which 372 satisfied the inclusion criteria. Among them 34 (9.1%) bleeding cases were reported with mean (+/- SD) age of 57.8 (+/- 14.19) years. Bleeding occurred mostly in males 79.4% and a HAS-BLED Score of > or = 3 has been observed in 67.6% (n = 23) patients out of 34 bled patients. Two antiplatelets + One anticoagulant is the most common combination which caused bleeding in 41.2% (n = 14). Stroke history, bleeding predisposition, labile INR's are the HAS-BLED risk factors which are significant (< 0.05) with the TIMI Bleeding Criteria.

CONCLUSION

There was a linear correlation between the HAS-BLED risk score and the TIMI bleeding criteria-higher the risk score the more frequent is the incidence of major bleeding. A HAS-BLED risk score of > or = 3 is associated with TIMI major bleeding.

Hepatoprotective activity of Indian Phyllanthus

CONTEXT

Phyllanthus (Euphorbiaceae) species are traditionally well-known for their medicinal properties including hepatoprotective activity.

OBJECTIVE

The study assessed the hepatoprotective and antioxidant activities of 11 Phyllanthus species, P. amarus Schumach., P. urinaria L., P. debilis Klein ex Willd, P. tenellus Roxb., P. virgatus G. Forst., P. maderaspatensis L., P. reticulatus Poir., P. polyphyllus Willd., P. emblica L., P. indofischerii Bennet. and P. acidus (L.) Skeels.

MATERIALS AND METHODS

The dried leaves and stems of each plant species were extracted in methanol and successively in water. The extracts were screened for hepatoprotective activity at a concentration of 50 µg/mL against tert-butyl hydroperoxide (t-BH) induced toxicity in HepG2 cells. Seven extracts from five species that showed hepatoprotective activity were assessed for their 50% effective concentration (EC₅₀) values and their antioxidant activity using a DPPH assay. Phyllanthin and hypophyllanthin contents were also determined in these Phyllanthus species.

RESULTS

The methanol extracts of P. polyphyllus, P. emblica and P. indofischeri showed high levels of hepatoprotective activity with EC₅₀ values of 12, 19 and 28 µg/mL and IC₅₀ of 3.77, 3.38 and 5.8 µg/mL for DPPH scavenging activity respectively against an IC₅₀ of 3.69 µg/mL for ascorbic acid. None of these activities could be attributed to phyllanthin and hypophyllanthin.

DISCUSSION AND CONCLUSION

The hepatoprotective and antioxidant activities of P. indofischeri are demonstrated for the first time in literature. The study also confirms the hepatoprotective and antioxidant activities of leaves of P. emblica and P. polyphyllus. The molecule(s) responsible for the activities is being investigated.

Biodiversity and chemodiversity: future perspectives in bioprospecting

Biological diversity and its constituent chemical diversity have served as one of the richest sources of bioprospecting leading to the discovery of some of the most important bioactive molecules for mankind. Despite this excellent record, in the recent past, however, bioprospecting of biological resources has met with little success; there has been a perceptible decline in the discovery of novel bioactive compounds. Several arguments have been proposed to explain the current poor success in bioprospecting. Among them, it has been argued that to bioprospect more biodiversity may not necessarily be productive, considering that chemical and functional diversity might not scale with biological diversity. In this paper, we offer a critique on the current perception of biodiversity and chemodiversity and ask to what extent it is relevant in the context of bioprospecting. First, using simple models, we analyze the relation among biodiversity, chemodiversity and functional redundancies in chemical plans of plants and argue that the biological space for exploration might still be wide open. Second, in the context of future bioprospecting, we argue that brute-force high throughput screening approaches alone are insufficient and cost ineffective in realizing bioprospecting success. Therefore, intelligent or non-random approaches to bioprospecting need to be adopted. We review here few examples of such approaches and show how these could be further developed and used in the future to accelerate the pace of discovery.

Stylish lengths: mate choice in flowers

The styles of flowers may represent an arena for pollen competition in the race to fertilize ovules. Accordingly, selection should favour a longer 'race' to better discriminate among variable pollen by increasing style length. Sampling across a taxonomically diverse range of wild and outcrossed species, we found that the distribution of style lengths within plants were skewed towards longer styles, as predicted. In self-pollinated domesticated species, where discrimination among pollen is less important, we found no such pattern. We conclude that style length is under directional selection towards longer styles as a mechanism for mate choice among pollen of variable quality.

Assessing species admixtures in raw drug trade of Phyllanthus, a hepato-protective plant using molecular tools

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus (Euphorbiaceae) species are well known for their hepato-protective activity and are used in several ethno-medicines in indigenous health care systems in India.

AIM OF THE STUDY

To assess species admixtures in raw drug trade of Phyllanthus using morphological and DNA barcoding tools.

MATERIALS AND METHODS

Samples of Phyllanthus used in raw drug trade were obtained from 25 shops in southern India. Species admixtures in the samples were assessed by identifying species using morpho-taxonomic keys. These identities were further validated by developing species specific DNA barcode signatures using the chloroplast DNA region, psbA-trnH. DNA from the market samples were extracted and amplified using the forward (psbAF - GTTATGCATGAACGTAATGCTC) and reverse primer (trnHR - CGCGCATGGTGGATTCACAAATC). The amplified products were sequenced at Chromous Biotech India, Bangalore. The sequences were manually edited using Chromas Lite. Species identities were established by constructing a neighbor-joining tree using MEGA V 4.0.

RESULTS

Morphological analysis of market samples revealed six different species of Phyllanthus in the trade samples. Seventy-six percent of the market samples contained Phyllanthus amarus as the predominant species (>95%) and thus were devoid of admixtures. The remaining 24% of the shops had five different species of Phyllanthus namely Phyllanthus debilis, Phyllanthus fraternus, Phyllanthus urinaria, Phyllanthus maderaspatensis, and Phyllanthus kozhikodianus. All identities, except those for Phyllanthus fraternus, were further confirmed by the species specific DNA barcode using chloroplast region psbA-trnH.

CONCLUSION

Our results show that market samples of Phyllanthus sold in southern India contain at least six different species, though among them, Phyllanthus amarus is predominant. DNA barcode, psbA-trnH region of the chloroplast can effectively discriminate Phyllanthus species and hence can be used to resolve species admixtures in the raw drug trade of Phyllanthus.

Endophytic fungal strains of Fusarium solani, from Apodytes dimidiata E. Mey. ex Arn (Icacinaceae) produce camptothecin, 10-hydroxycamptothecin and 9-methoxycamptothecin

Camptothecin and 10-hydroxycamptothecin are two important precursors for the synthesis of the clinically useful anticancer drugs, topotecan and irinotecan. In recent years, efforts have been made to identify novel plant and endophytic fungal sources of camptothecin and 10-hydroxycamptothecin. In this study we have isolated endophytic fungi strains from Apodytes dimidiata (Icacinaceae), a medium sized tree from the Western Ghats, India. The fungi were identified as Fusarium solani using both ITS rDNA sequencing and spore morphology. Two strains, MTCC 9667 and MTCC 9668 were isolated, both of which produced camptothecin and 9-methoxycamptothecin in their mycelia; one of the strains, MTCC 9668 also produced 10-hydroxycamptothecin, though in small amounts. The yields of camptothecin in MTCC 9667 and MTCC 9668 were 37 and 53 microg/100g, respectively, after 4 days of incubation in broth culture. The yields of 10-hydroxycamptothecin and 9-methoxycamptothecin in MTCC 9668 were 8.2 and 44.9 microg/100g, respectively. Further research in optimizing the culture conditions of these fungal strains might permit their application for the production of camptothecin and 10-hydroxycamptothecin.