Changes in Phyto-Chemical Status upon Viral Infections in Plant:A Critical Review

Most damaging plant diseases have been caused by viruses in the entire world.In tropical and subtropical areas,the damage caused by plant virus leads to great economic and agricultural losses.Single stranded DNA viruses(geminiviruses)are the most perilous pathogens which are responsible for major diseases in agronomic and horticultural crops.Significantly begomoviruses and mastreviruses are the biggest genus of plant infecting viruses,transmitted though Bemisia tabaci and members of Cicadellidae respectively.Plants possesses some naturally existing chemicals term as phyto-chemicals which perform important functions in the plant.Some antioxidant enzymes are used by plants for selfdefense upon foreign invasion of infection.This review explains the present perceptive of influence of viral infections on phyto-chemicals,oxidative enzymes and biochemical changes occurring in the plant.Viral infection mediated phytochemical changes in plants mainly includes:up and down regulation of photosynthetic pigment,increase in the concentration of phenolic compounds,elevation of starch content in the leaf and up&down regulation of anti-oxidative enzymes including(GPX)guaiacol peroxidase,(PPO)polyphenol oxidase,(APX)ascorbate peroxidase,(SOD)superoxide dismutase and(CTA)catalase.These changes lead to initiation of hypersensitive response,by thicken of the leaf lamina,lignification under the leaf surface,blocking to stomatal openings,systematic cell death,generation of reactive oxidative species(ROS),activation of pathogen mediated resistance pathways i.e.,production of salicylic acid and jasmonic acid.Collectively all the physiological changes in the plant due to viral infection supports the activation of defense mechanism of the plant to combat against viral infection by limiting virus in specific area,followed with the production of barriers for pathogen,accumulation of starch in the leaf and excess production of(ROS).These strategies used by the plant to prevent the spread of virus in whole plant and to minimize the risk of severe yield loss.

Self-medication with nutritional supplements and herbal over-the-counter products

In recent years,the popularity increased for nutritional supplements and herbal products.Prescription drugs,but not herbal therapies are paid by health insurances.They are sold over-the-counter(OTC)on the patients’own expense.However,there are potential risks of self-medication,e.g.incorrect self-diagnosis,severe adverse reactions,dangerous drug interactions,risk of addiction etc.They are often used by patients at their own discretion without knowledge of and control by their physicians.Certain users are at risk of intoxication.Multiple medications taken by older patients increase the risk for adverse drug reactions,drug-drug interactions,and compliance problems for this age group(polypharmacy).Herbals should be discontinued prior to operations to avoid interactions with anesthetics or anticoagulants.Herbal preparations may also be carcinogenic or interfere with cancer treatments.Pregnant women use various OTC preparations.However,in many cases,it is unclear whether their use is safe for mother or baby.Self-medication with herbals is also largely distributed among anxious and depressive patients,and patients with other conditions and symptoms.The popularity of herbal products has also brought concerns on quality,efficacy and safety.Cases of botanical misidentification,contaminations with heavy metals,pesticides,radioactivity,organic solvents,microbials as well as adulteration with chemical drugs necessitate the establishment of international quality control standards.Hepatotoxic effects have been reported for more than 300 plant species,and some commonly used herbs have been demonstrated to interact with Western medication.Health care professionals have a critical responsibility assessing the self-care ability of their patients.Databases are available for pharmacists with information on action,side effects and toxicities as well as herbdrug interactions.There is a need for established guidelines regarding the correct use of nutritional supplements and herbal OTC preparations(phytovigilance).Physicians,pharmacists,and other health care professionals have to counsel patients and the general public on the benefits and risks associated with herbal drugs.Information centers for consumers and general practitioners are needed,and convincing evidence on safety and efficacy of herbal products has to be demonstrated in placebo-controlled,double blind and randomized clinical trials.

Anti-cancer potential of South Asian plants

Phyto-chemicals are increasingly being used in the treatment of cancer because of their availability,potential anti-cancer activity with less adverse effects when compared with chemotherapy.The variation of climate and geography in South Asian countries provides a nursing environment for the growth of versatile plant species,that are repeatedly drawing attention of the scientific community.In this review,we have focused on the anti-cancer potential of thirty plants,which are commonly found in Bangladesh,India,Nepal,Pakistan and Sri Lanka,with their mechanisms of action.In particular,we have discussed the bio-active components that display anti-cancer activity,which have been identified in these plants.This review may help researchers to profile plants with known anti-cancer effect of this region and further investigations of anti-cancer agents in medicinal plants from South Asia.

Evaluation of <i>In-Vitro</i>Anti-Tuberculosis Activity of <i>Tetrapleura tetraptera</i>Crude and Fractions on Multidrug Resistant <i>Mycobacterium tuberculosis</i>

The management, control and elimination of tuberculosis (TB) have been difficult with the advent of HIV and cases of multidrug resistant (MDR-TB) tuberculosis. The cases of multidrug resistance to rifampicin and isoniazid pose greater challenges on first line and second line drugs to eliminate TB. The study is aimed at establishing anti-tuberculosis activity of Tetrapleura tetraptera against Mycobacterium tuberculosis and MDR-TB and the phytochemical present. The leaves of Tetrapleura tetraptera were collected, weighed, dried and pulverized to powder. The pulverized leaves of Tetrapleura tetraptera were subjected to 70% methanol extraction and screened for phytochemical. The crude extract was further purified into fractions using silica gel and thin layer chromatography techniques. M. tuberculosis and MDR-TB were obtained from positive acid fast bacilli sputa of TB patients and confirmed using GeneXpert to differentiate genotypic drug susceptible M. tuberculosis and MDR-TB. The sputa were digested using sodium hydroxide-cysteine technique and cultured in Middlebrook 7H9. The crude extract and fractions were screened for anti-tuberculosis activity using tetrazolium microtitre plate assay. The results showed that Tetrapleura tetraptera crude had activities against M. tuberculosis at 7.4 ± 0 mg/ml and 27.5 ± 0 mg/ml for MDR-TB. One of the fractions inhibited the growth of M. tuberculosis at 0.24 ± 0 mg/ml and MDR-TB at 0.89 ± 0 mg/ml. The phytochemical screened includes tannins, alkaloids, saponins, flavonoids, phenols and resins. T. tetraptra possesses anti-tuberculosis potential at low concentration on MDR-TB and can be a lead compound in drug development for the treatment of tuberculosis and multidrug resistant tuberculosis.