AbstractIntroduction

The endemic species Nepeta cyrenaica Quézel & Zaffran, native to northeastern Libya, is valued as an important honey-bearing plant.

Objectives

This study was aimed to examine the micromorphology, phytochemistry, and bioactivity of in vitro-propagated N. cyrenaica for the first time.

Materials and Methods

The leaf indumentum was examined using light and scanning electron microscopy and further characterised for histochemistry. The chemical composition of essential oil (EO) was performed using GC-MS analysis, while dichloromethane (DCM), methanol (ME), ethanol (ET), and aqueous (AQ) extracts were analysed using qualitative and quantitative LC/MS analyses. The antioxidant activities of EO and extracts were assessed using three parallel assays, while enzyme-inhibiting effects were evaluated against four enzymes.

Results

The leaves bear various types of glandular trichomes, with lipophilic secretion predominating. The main EO component of EO was 1,8-cineole. A considerable number of phenolics and iridoids were tentatively identified in the ME extract. Quantitative LC/MS analysis confirmed that ferulic acid, rosmarinic acid, and epigallocatechin gallate were present in the highest amount in the extracts, in which three iridoids were also quantified. Although the ME extract contained the highest amount of polyphenolics and iridoids, the DCM extract showed the best overall biological potential. Additionally, EO exerted the strongest acetylcholinesterase and tyrosinase inhibition.

Conclusion

This study demonstrated that the endemic N. cyrenaica can be efficiently grown under in vitro conditions, where it develops various glandular trichomes that are thought to secrete and/or accumulate bioactive compounds with valuable medicinal potential.

Abstract:

Nepeta cyrenaica Quézel & Zaffran (Lamiaceae), an endemic species of Libyan flora, is here characterized for the first time for its phytochemical composition and biological activities. Phenolic composition, antioxidant and enzyme inhibiting effects of extracts, prepared from five-week-old in vitro propagated N. cyrenaica shoots, were evaluated. Extraction was performed using dichloromethane, methanol, 96% ethanol or hot distilled water. LC-MS analysis showed that the methanol extract contained the highest amount of phenolic components, especially ferulic and rosmarinic acids (1300.73 mg/kg and 528.88 mg/kg, respectively), and epigallocatechin gallate (719.05 mg/kg). The strongest antioxidant activity was recorded for aqueous extract in DPPH assay (66.91%) and dichloromethane extract in β-carotene bleaching assay (81.06%), both tested at the concentration of 2 mg/mL. Concerning α-glucosidase inhibition, dichloromethane extract was shown to possess a higher inhibition capacity than acarbose at the concentration of 2 mg/mL (95.33% vs. 88.29%). The aqueous extract exhibited higher acetylcholinesterase inhibition than the other tested extracts, which was lower compared to the positive control, galantamine. Although methanol extract contained the highest amount of polyphenolics, dichloromethane and aqueous extracts were shown to be more suitable for the extraction of bioactive components. In conclusion, endemic N. cyrenaica could be efficiently propagated through in vitro propagation protocols as a polyphenolic-rich plant with valuable medicinal potential.

Keywords: biological activities; extracts; in vitro propagation; Nepeta cyrenaica

Abstract

Abstract

Introduction:

Coronavirus Disease 2019 (COVID-19) is an infectious res-

piratory disease caused by SARS-CoV-2. The disease was first broke out in

Wuhan City, Hubei Province, China and subsequently spread to all countries

and was considered by WHO as a worldwide pandemic. This study is aimed

to determine the epidemiology of SARS-CoV-2 and the presence of UK va-

riants in Zintan city of Libya taking some risk factors into account. Me-

thods: In a cross-sectional retrospective study, a total of 15486 nasopha-

ryngeal swabs were collected from COVID-19 suspected patients, travelers

and people need disease-free certificates for hospital admission, etc. The

samples were collected during the period from August 2020 to June 2021

and tested using real-time RT -PCR (rRT-PCR) kits for SARS-CoV-2 and

UK variants. Age groups, sex, and monthly weather were considered as risk

factors. Results: The positivity rate of COVID-19 in Zintan city was esti-

mated to be (3891; 25.12%) for the period from August 2020 to June 2021.

Females showed significantly (p < 0.05) higher positivity rate (2100; 54%) as

compared to males (1791; 46%). Out of the 3891 positive cases, 52 were de-

ceased. The Case Fatality Rate (CFR) was 1.33 recorded significantly in cas-

es aged ≥ 65 years which was higher in males (56.66%) than females (43.33%).

The peak of the first wave of infection was recorded in October 2020 (590;

15.15%) whereas the peak of the second wave of infection was recorded in

April 2021 (727; 18.71%). The positivity rate was decreased as the tempera-

ture increased. UK variant is detected firstly in May 2021 with the percen-

tage of 6.2% of tested samples. Conclusions: Health Authorities are en-

crease phase of infection to stop transmission of the virus in the next wave.

Early detection of new variants and studying their genetic characteristics

play a valuable role in prevention and control.

Keywords

SARS

-

CoV

-

2, UK Variant, Epidemiology, Zintan,

Libya, rRT

-

PCR.

Abstract and figures

We performed a comprehensive study of trichomes considering the medicinal importance of the essential oils produced in glandular trichomes of Salvia aegyptiaca L. and lack of data about leaf trichome characteristics. Micromorphological and histochemical analyses of the trichomes of S. aegyptiaca were carried out using light and scanning electron microscopy. We report that the leaves contained abundant non-glandular unbranched trichomes and two types of glandular trichomes, peltate and capitate, on both leaf surfaces. The abaxial leaf side was covered with numerous peltate and capitate trichomes, while capitate trichomes were more abundant on the adaxial leaf side, where peltate trichomes were rarely observed. The non-glandular trichomes were unicellular papillae and multicellular, uniseriate, two-to-six-celled, erect or slightly leaning toward the epidermis. Peltate trichomes were composed of a basal cell, a short cylindrical stalk cell and a broad head of eight secretory cells arranged in a single circle. Capitate trichomes consisted of a one-celled glandular head, subtended by a stalk of variable length, and classified into two types: Capitate trichomes type I (or short-stalked glandular trichomes) and capitate trichomes type II (or long-stalked glandular trichomes). Histochemical tests showed that the secreted material in all types of S. aegyptiaca glandular trichomes was of a complex nature. Positive reactions to lipids for both types of glandular trichomes were obtained, with especially abundant secretion observed in peltate and capitate trichomes type II.

Abstract

Aims: In the present work, the Libyan wild-growing Thymus capitatus essential oil (EO) was evaluated for its biological properties.

Methods and results: Carvacrol (68.19%) and thymol (12.29%) were found to be the main compounds of the oil. Antioxidant properties, determined by 2,2-diphenylpicrylhydrazyl (DPPH) assay, revealed that IC50 values were 119, 403 and 105 μg ml(-1) for oil, thymol and carvacrol respectively. Microdilution method showed strong antibacterial and especially antifungal potential. Tetrazolium (MTT) colorimetric assay indicated moderate cytotoxicity towards human cell lines MRC-5, HCT 116 and HT-29 (IC50 = 30-150 μg ml(-1)). In adhesion-inhibition assay oil and main compounds reduced adhesion of Escherichia coli and Listeria monocytogenes on colon cells HT-29 (51 and 39% of inhibition against L. monocytogenes and E. coli respectively).

Conclusions: Essential oil of Th. capitatus showed moderate cytotoxic activity, together with excellent antimicrobial effect, in particular against fungi, and significant potential to reduce pathogen colonization in colon.