Azra N. Kamili

Fungal endophytes as prolific source of phytochemicals and other bioactive natural products: A review

Endophytic fungi are those that live internally in apparently healthy and asymptomatic hosts. Endophytic fungi appear to be ubiquitous; indeed, no study has yet shown the existence of a plant species without endophytes. High species diversity is another characteristic of endophytic mycobiota which is depicted by the fact that it is quite common for endophyte surveys to find assemblages consisting of more than 30 fungal species per host plant species. Medicinal plants had been used to isolate and characterize directly the bioactive metabolites. However, the discovery of fungal endophytes inside these plants with capacity to produce the same compounds shifted the focus of new drug sources from plants to fungi. Bioactive natural products from endophytic fungi, isolated from different plant species, are attracting considerable attention from natural product chemists and biologists alike which is clearly depicted by the steady increase of publications devoted to this topic during the recent years. This review will highlight the chemical potential of endophytic fungi with focus on the detection of pharmaceutically valuable plant constituents as products of fungal biosynthesis. In addition, it will cover newly discovered endophytic fungi and also new bioactive metabolites reported in recent years from fungal endophytes. It summarizes the up-to-date and comprehensive information on bioactive compounds from endophytic fungi by having done a thorough survey of literature.

In vivo anticoccidial activity of berberine [18, 5,6-dihydro-9,10-dimethoxybenzo(g)-1,3-benzodioxolo(5,6-a) quinolizinium] – An isoquinoline alkaloid present in the root bark of Berberis lycium

Coccidiosis, caused by various Eimeria species, is a major parasitic disease in chicken. However the increasing resistance of these parasites to currently used anticoccidial drugs has stimulated the search for new methods of control. As part of this effort we investigated the root bark of Berberis lycium (barberry) as a potential source of compounds with anticoccidial activity. In the present study anticoccidial activity of different solvent extracts of the root bark of B. lycium and berberine was evaluated in vivo using broiler chicken. Results of the study demonstrated equipotent efficacy of pure berberine in comparison to that of standard drug amprolium on the basis of reduction in coccidian oocyst output, body weight gain of chicken and feed conversion ratio. Among the extracts crude methanolic extract showed highest anticoccidial activity tested at 300 mg/kg body weight which could be due to the presence of alcohol-soluble active ingredients in root bark of B. lycium. Toxicological studies revealed that B. lycium extracts as well as berberine were not lethal up to dosage of 2000 mg/kg body weight. LD(50) was not determined as mortalities were not recorded in any of the five groups of chicken. From the present study it can be concluded that root bark of B. lycium has the immense potential to contribute to the control of coccidian parasites of chicken. Our results corroborate the use of berberine for treatment of severe diarrhoea, amoebiasis and intestinal infections and could justify its use in folk medicine for treatment of haemorrhagic dysentery.

Current Perspectives on Plant Growth-Promoting Rhizobacteria

The rhizosphere of plant species is an inimitable ecosystem that harbors an extensive range of microbes. Research in the wide areas of rhizosphere biotechnology highlighting new bioinoculants has received ample attention during recent past, and suitable expertises have been developed. However, the global recognition of such technologies by farmers is still overwhelmed with doubts owing to limited shelf-life and efficiency of the products which demonstrate discrepancies. This review illustrates plant growth-promoting rhizobacteria with detailed emphasis on nutrient acquisition and potential roles in conferring tolerance against abiotic stresses. The review demonstrates the recent research in the field of genomic and proteomic analysis, where systematic characterization of potentially effective rhizobacteria is being carried out by screening the extensive bacterial gene pool based on modern molecular tools. The review concludes by emphasizing the efforts made in the proteomics field which could compensate for understanding of prompt evolution in microbe-derived and plant-derived protein and metabolite substitute that activates vulnerability or resistance.

Antibacterial and antioxidant activity of methanol extracts of Crocus sativus L. c.v. Kashmirianus

In this study, we investigated the antibacterial and antioxidant activities of Crocus sativus L. Kashmirianus c.v. extracts (callus and stigmas). Profuse callus was obtained on MS medium enriched with BAP (20 μ M)+NAA (15 μ M) under in vitro conditions from corm slices. Four pathogenic bacterial strains (Staphylococcus aureus CD0001, Escherichia coli CD0006, Pseudomonas aeruginosa CD0023 and Shigella flexneri CD0033) were used for determining the antibacterial activity of extracts. The antioxidant activity was determined by DPPH assay, DNA protection assay, FTC method, TBA assay and lipid peroxidation assay. The methanol stigma extract of saffron was found to be more effective in inhibiting all the pathogenic strains. The stigma extract also showed significant radical scavenging or chelation capacities in four of the methods; however, callus extract exhibited maximum inhibition of peroxy- radicals in lipid peroxidation assay. The protocol for callus production is described. It was concluded that as well as the specific parts of plants displaying diverse pharmacological activities, callus produced under in vitro conditions will assist in enhancing the production of secondary metabolites, which will reduce the pressure on natural saffron.

In vitro cormlet production of saffron (Crocus sativus L. Kashmirianus) and their flowering response under greenhouse

A complete protocol for the saffron cormlet production under in vitro conditions and subsequent flowering under greenhouse conditions is described. Highest number of cormlets (70.0 ± 0.30) per corm slice (explant) could be regenerated on Murashige and Skoog (MS) half strength medium supplemented with thidiazuron (TDZ) (20 µM), Indole acetic acid (IAA) (10 µM), and sucrose (40 g/l). Maximum germination (90%) of these cormlets could be achieved on MS medium containing 6-benzyl amino purine (BAP) (20 µM) and α-naphthalene acetic acid (NAA) (15 µM). In order to increase the size of the in vitro raised cormlets, these were cultured on MS medium containing TDZ (15 µM) and IAA in the range of 1.5-30 µM. Maximum increase in cormlet size could be attained on TDZ (15 µM) + IAA (12.5 µM) + sucrose (30 g/l), and the average size of cormlets was 2.5g. In another experiment, apical vegetative buds of actively growing corms were cultured for cormlet development, and corms of size 2.5g could be developed on MS medium with NAA (15 µM), BAP (20 µM), and sucrose (30 g/l). The in vitro developed cormlets were dried under shade at 25 ± 2°C for 7 d. These were then planted in small cups containing clay loam soil and kept in green house at 20 ± 2°C. In vitro developed cormlets with mean weight 2.5 g showed maximum flowering (25%) as well as vegetative growth (55%), while only 19% cormlets of 2.0 g flowered. To our knowledge this is the first report on successful flowering from in vitro raised cormlets under greenhouse.

Antioxidant potential in callus culture of Artemisia amygdalina Decne.

This study was conducted to analyse the free radical scavenging potential of callus obtained from nodal segments and leaf explants of Artemisia amygdalina Decne. The explants were inoculated on MS medium augmented with various concentrations of BAP, Kn, NAA and 2,4-D for callus induction. In this study, 12.42 g of callus developed from the leaf explant on MS (NAA 10 + BAP 7.5 µM) and 8.81 g of callus developed from nodal explant on NAA 2 µM+BAP 2 µM. Callus raised from both explants on all treatments seemed non-regenerative but BAP 2 µM produced 7.33 shoots and BAP 15 µM produced callus and 5 shoots per nodal segment. Callus was analysed for antioxidant activity via DPPH, riboflavin photoxidation and DNA damage assays. Methanol and aqueous extracts show more scavenging in DPPH, deoxyribose assay and in contrast, petroleum ether and ethyl acetate extracts show higher activity in riboflavin photoxidation assay. Tocopherol, ascorbic acid and BHT were used as controls.

Comparative GC–FID and GC–MS analysis of the mono and sesquiterpene secondary metabolites produced by the field grown and micropropagated plants of Artemisia amygdalina Decne

The essential oil obtained by hydrodistillation from the leaves of micropropagated plants of Artemisia amygdalina was analyzed by capillary GC–FID and GC–MS and compared with that obtained from the leaves of field growing parent plants. The oil yield from the micropropagated plants was lower (0.05% v/w) than the oil yield obtained from field-grown plants (0.2% v/w). The major constituents of the field-grown plants were p-cymene (21.0%), 1,8-cineole (24.9%), α-terpineol (5.9%), β-caryophyllene (4.7%), germacrene D (4.0%), while as the major constituents from the micropropagated plants were p-cymene (11.3%),1,8-cineole (10.2%), borneol (7.9%), α-longipinene (5.5%), α-copaene (5.5%) and β-caryophyllene (17%). The essential oil from field-grown plant was dominated by the presence of oxygenated monoterpenes (41.5%), monoterpene hydrocarbons (35.9%) and sesquiterpene hydrocarbons (16.3%) while as the essential oil of micropropagated plants was characterized by sesquiterpene hydrocarbons (40.0%), oxygenated monoterpenes (25.2%) and monoterpene hydrocarbons (21.6%).

Differential response of terpenes and anthraquinones derivatives in Rumex dentatus and Lavandula officinalis to harsh winters across north-western Himalaya

Herbs adapted to diverse climates exhibit distinct variability to fluctuating temperatures and demonstrate various metabolic and physiological adaptations to harsh environments. In this research, Rumex dentatus L. and Lavandula officinalis L. were collected before snowfall in September–November to evaluate variability in major phytoconstituents to diverse seasonal regime. LC-MS was used for simultaneous determination of eight anthraquinone derivatives in R. dentatus, i.e. emodin, physcion, chrysophanol, physcion glucoside, endocrocin, emodin glucoside, chrysophanol glucoside and chromone derivatives and monoterpenes in L. officinalis i.e. (Z)-β-ocimene, (E)-β-ocimene, terpene alcohol, terpin-4-ol, acetate ester-linalyl acetate and bicyclic sesquiterpene (E)-caryophyllene. The correlation analysis confirmed significant variation in anthraquinone glucoside and terpene content within Rumex and Lavender, respectively, and altitude was established as the determinant factor in secondary metabolism of both herbs. The study concludes the propagation of herbs in bioclimatic belts which favour accumulation of major constituents and validate their greater pharmacological activity.

Variation in adaptation mechanisms of medicinal herbs to the extreme winter conditions across the North Western Himalaya

The North Western Himalaya region is characterized by extreme seasonal variability and local changes in microclimate. Plants adapted to this region demonstrate marked variability to the extreme winter conditions. This region, designated as a biodiversity hotspot, is rich in medicinal herbs, which exhibit diverse growth and adaptation mechanisms to the harsh environment. In the present study, physiological mechanisms of adaptation to the winter season conditions were compared in five medicinal herbs. Components of the photosynthetic machinery, and osmoregulation which are of importance for secondary metabolism is not well known in these alpine herbs and was studied. The medicinal herbs Rumex dentatus, Atropa accuminata, Lupinus polyphyllus, Hyoscyamus niger, and Lavandula officinalis were collected before snowfall in September–November to evaluate variability in metabolic and physiological responses to the varied seasonal regimes. Plants were followed over a period of 8 weeks (summer to early winter) in th...

Screening of beneficial properties of rhizobacteria isolated from Saffron (Crocus sativus L) rhizosphere

Plant growth promoting rhizobacterias (PGPRs) are free living soil bacteria that colonize root surfaces and have the capacity to enhance plant growth directly or indirectly. A total of 23 bacterial strains were isolated from saffron rhizoshere soil during the flowering stage of corms. All these isolates were screened for their plant growth promoting traits like production of IAA, phosphate solubilisation activity and siderophore production. The maximum percentage of the bacterial isolates was of Gram negative rod shaped type. A total of six isolates were capable of showing one or more than one of the activities like IAA production, Siderphore production and phosphate solubilisation activity. The Bacillus subtilis showed highest IAA production of 360 µg/ml while as Pseudomonas ssp., was found to be highly efficient in terms of phosphate solubilisation production (460 µg/ml) and siderophore production (62%). It was concluded from the results that these rhizobacterial strains isolated could be a promising source for plant growth promoting agent in increasing the growth of cormlets vis a vis enhancing the yield of saffron.