Effect of altitude and solvent on Psidium guajava Linn. leaves extracts: phytochemical analysis, antioxidant, cytotoxicity and antimicrobial activity against food spoilage microbes

BACKGROUND

Guava (Psidium guajava Linn.) has been traditionally used in the treatment of a wide range of diseases due to its rich content of secondary metabolites.

AIM

This study was aimed to evaluate the effect of altitude and solvent systems on guava leaves crude extract's phenolics and flavonoid content, antioxidant, antimicrobial, and toxicity nature.

METHODS

Guava leaves were collected from three different geographical locations in Nepal while solvents with an increasing polarity index were used for extraction. The yield percentage of extracts was calculated. Total Phenolic Content, Total Flavonoid Content, and antioxidant activity were determined by the Folin-Ciocalteu method, Aluminium chloride colorimetric method, and DPPH (2,2'-Diphenyl-1-picrylhydrazyl) assay respectively. The quantification of fisetin and quercetin was performed using the HPLC with method validation. The antimicrobial activity of the extracts was tested against bacteria and fungus isolated from spoiled fruits and vegetables and identified through 16s and 18s rRNA sequencing. Finally, Brine Shrimp Lethality Assay (BSLA) was used for testing the toxicity of the extracts.

RESULTS

The phenolic and total flavonoid content was found to be higher in ethanol extract (331.84 mg GAE/g dry extract) and methanol extract (95.53 mg QE/g dry extract) from Kuleshwor respectively. Water extract of guava leaves from Kuleshwor (WGK) did not show significantly different antioxidant activity when compared to methanol and ethanol extracts. Fisetin and quercetin were higher in WGK (1.176 mg/100 g) and (10.967 mg/100 g) dry extract weight respectively. Antibacterial activity against food spoilage bacteria was dose-dependent and found to be highest for all the extracts from different solvents and altitudes at higher concentrations (80 mg/ml). Similarly, methanol and ethanol guava extracts from all locations showed antifungal activity against Geotrichum candidum RIBB-SCM43 and Geotrichum candidum RIBB-SCM44. WGK was found to be non-toxic.

CONCLUSION

Our study concludes that the antioxidant and antimicrobial activity of WGK was found to be similar statistically to that of methanol and ethanol extracts of Bishnupur Katti and Mahajidiya. These results suggest the possibility of using water as a sustainable solvent to extract natural antioxidant and antimicrobial compounds which can further be used as natural preservatives to extend the shelf life of fruits and vegetables.

SARS-CoV-2 vaccine development: where are we?

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has proved to be one of the most challenging infectious diseases in the modern era, and despite several countermeasures to lessen its impact, the spread of the virus is still affecting most countries. This renders the goal of active immunization of the population through vaccination a worldwide public health priority. In fact, only when efficient vaccination programs will be successfully implemented, a return to pre-pandemic normality can be considered. The scientific community has made a tremendous effort to blow the lid off the pathogenesis of the disease, and unprecedented efforts are ongoing with governments, private organizations, and academics working together to expeditiously develop safe and efficacious vaccines. Previous research efforts in the development of vaccines for other coronaviruses (Severe Acute Respiratory Syndrome Coronavirus 1 and Middle East Respiratory Syndrome Coronavirus) as well other emerging viruses have opened the door for exploiting several strategies to design a new vaccine against the pandemic virus. Indeed, in a few months, a stunning number of vaccines have been proposed, and almost 50 putative vaccine candidates have entered clinical trials. The different vaccine candidates use different vaccine development platforms, from inactivated whole virus vaccine to subunit vaccine, nucleic acid, and vectored vaccines. In this review, we describe strengths, flaws, and potential pitfalls of each approach to understand their chances of success.

Understanding of tobacco and lung cancer among medical students in Kathmandu University School of Medical Sciences (KUSMS)

BACKGROUND

Often, lung cancer is diagnosed at terminal stages. Poor awareness about the symptoms or risk factors of lung cancer among medics may be one of the factors for delayed diagnosis.

OBJECTIVE

We explored the knowledge of medical students and their behavior with the patients of lung cancer.

METHOD

Qualitative and quantitative approaches were used for data collection from 153 medical student of Kathmandu University School of Medical Sciences from December 2011 to May 2012.

RESULTS

Among the results, eighty-nine students had over 80% knowledge of the 14 cancer warning signs, among them 83% knew the nine risk factors for lung cancer. Twenty-three students told lung cancer can be hereditary. Sixty five percent of all participants believed that lung cancer can be detected at early stage; of them 81% told that it can be treated. About 24% of the total students were current or exsmokers and about half of them believed that lung cancer does not occur in light smokers. Only 10% have heard of Framework Convention on Tobacco Control in Nepal.

CONCLUSION

Study finds that all medical students who know about any cancers may not necessarily have knowledge about lung cancers. Their perception about the cause of lung cancer may be influenced by their smoking behavior and there was little knowledge of public health measures for smoking control. Awareness about national policies needs to be increased.

[Preliminary results concerning the effectiveness of early intervention from the STEEP practice research project "WiEge"]

Preliminary results of the attachment-based STEEP(TM) (Steps toward effective and enjoyable parenting) research practice project "WiEge" are presented. Within a multisite, longitudinal intervention study, young high-risk mothers enrolled in the 2-year STEEP(TM) program have developed significantly more secure attachment relationships with their 1-year old children compared to mothers of the control group, who received the standard support as usual in the German welfare system. Age of mothers at birth of their children, educational level, single motherhood status, and mental health diagnoses indicate that both groups are comparable. A global measure of risk status indicates that mothers of the STEEP(TM) group confront even more risks than control group mothers. Additional data on depression (Edinburgh postnatal depression scale, EPDS), parenting stress (PSI), or risky parental attitudes (Adult-Adolescent Parenting Interview®, AAPI) are being presented and discussed with regard to the differences found being an effect of the STEEP(TM) program. Since the focus of the STEEP(TM) program is on empirically validated mechanisms in attachment development, it is also important that the results are in line with attachment theory. At the same time, we did not find significant group differences with regard to attachment disorganization. Supporting mothers in being more sensitive and to improve on reflective functioning--as being done in STEEP(TM)--does not seem to be sufficient to prevent attachment disorganization, as others studies have also shown. Although based on small sample sizes, the results are informative for improving intervention strategies, which need to focus more on the developmental process underlying attachment disorganization, i.e., unusual parental behavior.

[Placenta accreta with placenta previa after previous cesarean sections--a growing danger in modern obstetrics]

The increased rate of cesarean sections in recent decades has brought with it an increase in the frequency of placenta accreta. There are direct correlations between previous cesarean deliveries and also maternal age, with the risk of placenta accreta. There is also a direct correlation between placenta accreta and placenta previa. The risk of placenta accreta in women who have had placenta previa is 2% for those younger than 35 years and with no history of uterine surgery. The risk increases to 39% for those over 35 who have had 2 or more cesarean sections. We present 3 cases of placenta accreta admitted in 15 months, all of whom had a history of cesarean sections. The frequency of placenta accreta in our hospital is 1:1,579 deliveries, in line with the 1:1,420 in the literature. We consider hysterectomy the treatment of choice for this serious complication. When performing a cesarean in cases of placenta previa with a history of cesarean sections, the possibility of placenta accreta should be considered.