Cloning and expression analysis of chalcone synthase gene from Coleus forskohlii.

Flavonoids are an important class of secondary metabolites that play various roles in plants such as mediating defense, floral pigmentation and plant-microbe interaction. Flavonoids are also known to possess antioxidant and antimicrobial activities. Coleus forskohlii (Willd.) Briq. (Lamiaceae) is an important medicinal herb with a diverse metabolic profile, including production of a flavonoid, genkwanin. However, components of the flavonoid pathway have not yet been studied in this plant. Chalcone synthase (CHS) catalyses the first committed step of flavonoid biosynthetic pathway. Full-length cDNA, showing homology with plant CHS gene was isolated from leaves of C. forskohlii and named CfCHS (GenBank accession no. KF643243). Theoretical translation of CfCHS nucleotide sequence shows that it encodes a protein of 391 amino acids with a molecular weight of 42.75 kDa and pI 6.57. Expression analysis of CfCHS in different tissues and elicitor treatments showed that methyl jasmonate (MeJA) strongly induced its expression. Total flavonoids content and antioxidant activity of C. forskohlii also got enhanced in response to MeJA, which correlated with increased CfCHS expression. Induction of CfCHS by MeJA suggest its involvement in production of flavonoids, providing protection from microbes during herbivory or mechanical wounding. Further, our in silico predictions and experimental data suggested that CfCHS may be posttranscriptionally regulated by miR34.

Microclimatic variation in UV perception and related disparity in tropane and quinolizidine alkaloid composition of Atropa acuminata, Lupinus polyphyllus and Hyoscyamus niger.

The aim of current research was to evaluate the physiological adjustment in three medicinal herbs viz., Atropa acuminata, Lupinus polyphyllus and Hyoscyamus niger to the winter period characterised by intense UV flux in Kashmir valley across the North Western Himalaya. Quinolizidine (QA) and tropane alkaloid (TA) concentrations were analysed in these herbs thriving at two different altitudes via GC-MS and correlated by PCA analysis. This study investigated the hypothesis that UV reflectance and absorbance at low temperatures are directly related to disparity in alkaloid accumulation. Among QAs in L. polyphyllus, ammodendrine and lupanine accumulated at higher concentration and exhibited significant variation of 186.36% and 95.91% in ammodendrine and lupanine respectively in both sites. Tetrahydrohombifoline displayed non-significant variation of about 9.60% irrespective of sites. Among tropane alkaloid (TA), hyoscyamine was recorded as the most abundant constituent irrespective of the plant and site while apotropine accumulated in lesser quantity in A. acuminata than H. niger. However, apotropine demonstrated significant variation of 175% among both sites. The final concentration of quinolizidine (QA) and tropane alkaloid (TA) reflects the interplay between reflectance and absorbance of UV radiation response field. These findings suggest that spectral response of UV light contributes directly to alkaloid biosynthesis.

Changing trends in biotechnology of secondary metabolism in medicinal and aromatic plants.

MAIN CONCLUSION: Medicinal and aromatic plants are known to produce secondary metabolites that find uses as flavoring agents, fragrances, insecticides, dyes and drugs. Biotechnology offers several choices through which secondary metabolism in medicinal plants can be altered in innovative ways, to overproduce phytochemicals of interest, to reduce the content of toxic compounds or even to produce novel chemicals. Detailed investigation of chromatin organization and microRNAs affecting biosynthesis of secondary metabolites as well as exploring cryptic biosynthetic clusters and synthetic biology options, may provide additional ways to harness this resource. Plant secondary metabolites are a fascinating class of phytochemicals exhibiting immense chemical diversity. Considerable enigma regarding their natural biological functions and the vast array of pharmacological activities, amongst other uses, make secondary metabolites interesting and important candidates for research. Here, we present an update on changing trends in the biotechnological approaches that are used to understand and exploit the secondary metabolism in medicinal and aromatic plants. Bioprocessing in the form of suspension culture, organ culture or transformed hairy roots has been successful in scaling up secondary metabolite production in many cases. Pathway elucidation and metabolic engineering have been useful to get enhanced yield of the metabolite of interest; or, for producing novel metabolites. Heterologous expression of putative plant secondary metabolite biosynthesis genes in a microbe is useful to validate their functions, and in some cases, also, to produce plant metabolites in microbes. Endophytes, the microbes that normally colonize plant tissues, may also produce the phytochemicals produced by the host plant. The review also provides perspectives on future research in the field.

Pharmacological review of Caralluma R.Br. with special reference to appetite suppression and anti-obesity.

Caralluma fimbriata extract has received Generally Recognized As Safe (GRAS) status for use as a nutraceutical to combat the most serious public health concern (i.e., obesity). More than 260 species grouped under the genus Caralluma (Family Apocynaceae) are distributed in tropical Asia and Mediterranean regions of the globe. Ethnobotanically, some species have been used as traditional and modern dietary ingredients to suppress appetite. Many species of Caralluma are commonly used as traditional medicine for the treatment of rheumatism, diabetes, leprosy, paralysis, and inflammation and have antimalarial, antitrypanosomal, anti-ulcer, antioxidant, antinociceptive, and antiproliferative activities. The genus is known for compounds like pregnane glycosides, flavonoid glycoside, flavones, magastigmane glycosides, pregnane steroids, steroidal glycosides, saturated and unsaturated hydrocarbons, aromatic and nonaromatic volatile compounds, and ß-sitosterol. An extract of C. fimbriata (Slimaluna(®), Gencor Nutrients, Anaheim, CA, USA) is used as an anti-obesity agent and appetite suppressor. It is also seen that the pregnane glycosides isolated and identified from African Hoodia are reported as anti-obesity and appetite-suppressant compounds. On reviewing the studies undertaken on the chemistry, pharmacology, and therapeutic potential of Caralluma, it is concluded that the genus is also composed of pregnane glycosides as one of the major constituents. Availability of pregnane glycosides in Caralluma is an indication of the appetite-suppressant property of this genus. This coupled with the GRAS status of the extract of C. fimbriata has opened the possibility of developing an anti-obesity/appetite-suppressant product from other species of Caralluma. The main objective of this article is to review the studies undertaken on the plant in light of further research for anti-obesity drugs and nutraceuticals from species of Caralluma.

Medicinal plants and cancer chemoprevention.

Cancer is the second leading cause of death worldwide. Although great advancements have been made in the treatment and control of cancer progression, significant deficiencies and room for improvement remain. A number of undesired side effects sometimes occur during chemotherapy. Natural therapies, such as the use of plant-derived products in cancer treatment, may reduce adverse side effects. Currently, a few plant products are being used to treat cancer. However, a myriad of many plant products exist that have shown very promising anti-cancer properties in vitro, but have yet to be evaluated in humans. Further study is required to determine the efficacy of these plant products in treating cancers in humans. This review will focus on the various plant-derived chemical compounds that have, in recent years, shown promise as anticancer agents and will outline their potential mechanism of action.