The aim of this study was to determine the effect of different fertilizer doses and drying methods on total phenolic contents and antioxidant activity of organic white tea (Camellia sinensis (L.) Kuntze) obtained from Hemşin Valley, region of Rize/Turkey. The determination of phenolic constituents was done by the Folin-Ciocalteau method and the determination of antioxidant activity by the FRAP method. The results showed that the phenolic content of white tea was as follows: 443,7- 506,2 µg GAE/g DW in the drying oven, 421,4- 473,6 µg GAE/g DW in shadow and 434,4- 485,2 µg GAE/g DW in the liofilizator. According to the FRAP method the antioxidant activity was as follows: 1130,1-1176,9 mg FeSO4/gr DW in drying oven, 1141,2-1157,1 mg FeSO4/gr DW in shadow and 1005,3-1183,2 mg FeSO4/gr DW in lyophylizator. The results revealed that different fertilizer doses and drying methods had important effects on the total phenolic content and antioxidant activity of white tea.

In Vitro Multiplication of Stevia rebaudiana (Bertoni) Genotypes by Using Different Explants Fatih Seyis 1 , Emine Yurteri 1 , Aysel Özcan 1 1 Recep Tayyip Erdogan University, Faculty of Agronomy and Natural Sciences, Field Crops Department Stevia rebaudiana Bertoni that is a member of the Compositae family is one of the most valuable tropical medicinal plants. The origin of Stevia is South America, where it can be seen as a wild plant. Further it could be found in semi-arid habitat ranging from grassland to scrub forest to mountain terrain. Conventional cultivation or propagation methods of Stevia are as well known for time consuming, unpredictable, unreliable and less productive. Therefore, there is a crucial need to develop methods for rapid multiplication of this valuable plant. Plantlet produced through stem cutting has unstability, however the micropropagation of Stevia which may overcome some limitations associated with conventional method can be used for a rapid multiplication. Accordingly, the study results showed that different explants such as leaf, stem and root transferred to different tissue culture media for in vitro multiplication of two Stevia rebaudiana (Bertoni) genotypes could be reproduced by using different explants. Key words: Stevia rebaudiana, tissue culture, multiplication, in vitro , genotype, explant Corresponding author: fatih.seyis@erdogan.edu.tr

The development of antibiotic resistance has become a global health challenge, resulting in approximately 800,000 deaths per year. The rapid rise in multidrug-resistant (MDR) pathogens has prompted an urgent need for antimicrobial alternatives. Punica granatum L. peel has long been valued for its rich bioactive polyphenols with potent antimicrobial properties. In this study, P. granatum L. peel extract (PGPE) was integrated with chitosan nanoparticles (CH-PGPE) to enhance antimicrobial efficacy while minimizing potential cytotoxicity. The antimicrobial potential of PGPE and CH-PGPE was evaluated with agar well diffusion, disk diffusion, and minimum inhibitory concentration (MIC) analyses against standard ATCC and clinical MDR strains of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Staphylococcus aureus. MTT assay evaluated the biocompatibility and anti-proliferative potential of PGPE on ARPE-19 (normal retinal pigment epithelial), HeLa (human cervical cancer), and A549 (human lung carcinoma) cell lines. PGPE exhibited antibacterial activity, and CH-PGPE reduced MIC values by approximately two-fold. Both PGPE and CH-PGPE demonstrated comparable or superior inhibition compared to several conventional antibiotics, particularly against MDR strains. The MTT assay revealed that PGPE was non-cytotoxic to normal ARPE-19 cells, while exhibiting the highest antiproliferative potency against A549 cells and a moderate inhibitory response in HeLa cells. The nanoparticle-supported formulation enhanced the antimicrobial efficacy of PGPE and also exhibited selective anti-proliferative activity against cancer cells without affecting normal cells.

The genus Helichrysum contains many species displaying therapeutical effects and use in folk medicine. Helichrysum pallasii (Spreng.) Ledeb. is one of these species, used in the region for traditional medicine and ornamental purposes. Plants have been used in the treatment in folk medicines since the earliest times of human history. Chemical composition, antimicrobial and other medicinal properties of plants are being investigated in laboratories throughout the world using the extracts and essential oils derived from medicinal plants. Essential oils are usually complex mixtures of natural compounds of both polar and apolar structure. Essential oils consist mainly of terpenoids and their oxygenated derivatives. Essential oils, which have antioxidant and antimicrobial activities, have therapeutic properties and are the raw materials of cosmetics, as well as acting as natural additives in foods and food products. In this study, the volatile components of the H. pallasii plants were investigated which collected from its natural habitat in the Armutlu district of Bayburt province (Turkey) at the time of flowering. The proportion of essential oils of the plant harvested during the full flowering period and the aromatic components in the essential oil of the plant were determined using the SPME (Solid Phase Microextraction) method in a Gas Chromatography (GC-MS) device. Almost 37 different components were found as a result of the analysis. The main components were found as α-Springene (34.89%), (-)-Isoledene (7.11%), δ-Selinene (5.79%) and Aristolene (5.09).

Tea (Camellia sinensis) is the world's most popular beverage plant, as well as an important plantation crop with high commercial value. It has been maintained for centuries through conventional vegetative propagation. Tea clonal propagation in vitro has the advantage of producing a large number of elite plants. If an efficient in vitro regeneration technology is available, this technique could be exploited for selection of tea plants for desired trait. The selected plants could be later on multiplied through in vitro or ex vitro techniques. The study aimed to induced somatic embryogenesis from immature embryo explants to genetic variaton. Different concentrations of phenylboronic acid with benzyladenine and phenylboronic acid with kinetin were tested in MS medium with 30 g/L sucrose and 8 g/L agar. MS medium without any plant growth regulators was used as control group. Considering the embryo survival rate, 1.5 mg/ L-1 phenylboronic acid + 1 mg/ L-1 kinetin produced highest result as 87.3% while lowest was in control group as 36.7%. The highest plant regeneration rate was found in 1,5 mg/ L-1 phenylboronic acid + 1 mg/ L-1 kinetin and 1.5 mg/ L-1 phenylboronic acid + 1 mg/ L-1 benzyladenine medium respectively as 58.3% and 55.6%. Kinetin treatment with increasing phenylboronic acid concentrations gave the best results in terms of somatic embryo survival rate. Also, kinetin treatment produced better results when compared to benzyladenine concentrations.