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المنشورات البحثية

الجمعة 01/سبتمبر/2023

Design, Synthesis, and Toxicological Activities of Novel Insect Growth Regulators as Insecticidal Agents against Spodoptera littoralis (Boisd.)

Antar A. Abdelhamid, Safwat A. Aref, Nabila A. Ahmed, Ahmed M. M. Elsaghier, Fawy M. Abd El Latif, Sameera N. Al-Ghamdi, and Mohamed A. Gad

As a result of some major problems that come from using insecticides, the use of safe alternatives to these pesticides has become very necessary. Thus, a novel series of predicted toxicologically active urea, thiourea, thiosemicarbazide, oxadiazole, pyrazole, and triazine derivatives have been synthesized in a pure form to be lufenuron analogues as insect growth regulators which were screened and examined against Spodoptera littoralis (Boisd). The structure of synthesized compounds was established by means of spectroscopic and elemental analyses. Compounds b5, b2, b3, and a4 showed high insecticidal toxicity, and their LC50 values for the second larvae instar were found to be 26.63, 46.35, and 60.84 ppm, respectively, whereas the LC50 value for lufenuron as a reference insecticide was 17.01 ppm.

الجمعة 01/سبتمبر/2023

Toxicity of citronella essential oil and its nanoemulsion against the sawtoothed grain beetle Oryzaephilus surinamensis (Coleoptera: Silvanidae)

Fatehia Nasser Gharsan, Walaa Mohamed Kamel , Tariq Saeed Alghamdi , Azla Aedh Alghamdi , Abeer Olayana Althagafi , Fatima Jasim Aljassim , Sameera Nasser Al-Ghamdi

Sawtoothed grain beetles, Oryzaephilus surinamensis (Coleoptera: Silvanidae), cause severe damage to various stored products, reducing their quality and nutritional value. Several chemical pesticides have been introduced to control this pest and mitigate damage, but these pesticides also affect human health and the environment, enticing researchers to seek safer products and technology, such as plant-based products and nanotechnology. In this study, we compared the effectiveness of citronella essential oil and its nanoemulsion in controlling O. surinamensis adults. The citronella essential oil was obtained through hydrodistillation, and analyzed using gas chromatography (GC) and GC/mass spectrometry (MS based on the GC-MS analysis, the predominant compounds were citronellal (46.95%), citronellol (9.49%), linalool (9.46%), β-caryophyllene (8.39%). The particles size of the prepared nanoemulsion was 57.98 nm. The lethal concentration that causes 50% mortality (LC50) in O. surinamensis adults for the pure essential oil and its nanoemulsion was 10, 15, 20, and 25 µL/L. The nanoemulsion was more effective against both females (LC50 = 20.3 µL/L) and males (LC50 = 15.7 µL/L) than the pure essential oil (LC50 = 40.02 and 52.5 µL/L, respectively). There was a significant difference in toxicity between the pure essential oil and its nanoemulsion. In addition, there were statistically significant differences (P < 0.05) between males and females when using citronella nanoemulsion only. In conclusion, citronella nanoemulsion is effective in controlling O. surinamensis and represents a promising alternative to chemical pesticides for protecting stored products.

الجمعة 01/سبتمبر/2023

Synthesis of Novel Key Chromophoric Intermediates via C-C Coupling Reactions

Laila M. Nhari , Elham N. Bifari, Aisha R. Al-Marhabi, Huda A. Al-Ghamdi , Sameera N. Al-Ghamdi, Fatimah A. M. Al-Zahrani, Khalid O. Al-Footy and Reda M. El-Shishtawy

The fundamentals of Pd-catalyzed Csp2−Csp2 Miyaura borylation, Suzuki cross-coupling, and Stille cross-coupling reactions for a variety of borylated precursors based on phenothiazine (PTZ), phenoxazine (POZ), carbazole (Cz), and quinoxaline (QX) units have been explored. Three palladiumbased catalysts were chosen for this study: Pd(PPh3 )4 , Pd(PPh3 )2Cl2 , and Pd(dppf)Cl2 , applying different reaction conditions. Around 16 desired chromophores were successfully designed and synthesized using C-C cross-coupling reactions in moderate to excellent yields, including PTZ, POZ, and Cz units coupled with QX, indolinium iodide, thienyl, phenyl, or triphenylamine moieties. Additionally, PTZ, POZ, and Cz have been employed in synthesizing various pinacol boronate ester derivatives in good to moderate yields. Interestingly, Pd(dppf)Cl2 was found to be the best catalyst for borylation, and C-C cross-coupling reactions occurred in as little as 30 min, with an excellent yield exceeding 98%. Pd(PPh3 )4 and Pd(PPh3 )2Cl2 catalyzed the reaction to obtain the desired products in moderate to good yields after a long time (20–24 h). On the other hand, the Suzuki-Miyaura cross-coupling between N-(2-methyl)hexyl carbazole pinacol boronate ester derivative 10c and three halogenated quinoxaline derivatives—4-(3-(5-bromothiophen-2-yl)quinoxalin-2-yl)benzaldehyde (27), 4-(5-(3-(5- bromothiophen-2-yl)quinoxalin-2-yl)thiophen-2-yl)benzaldehyde (30), and 4-(3-chloroquinoxalin-2- yl)benzaldehyde (25) catalyzed by Pd(PPh3 )4—afforded three carbazole-quinoxaline chromophores (28, 30, and 31, respectively) in 2–3 h, with good to excellent yields reaching 86%. The electrondeficient QX couplers proved to be coupled efficiently using the Stille coupling reaction, which involves the coupling between electron-rich orgaostannane and electron-deficient halide. The synthesized precursors and desired chromophores were characterized by FTIR, 1H-NMR, 13C-NMR, and HRMS.

الجمعة 01/سبتمبر/2023

Synthesis of novel phenothiazine, phenoxazine and carbazole derivatives via Suzuki-Miyaura reaction

Laila M. Nhari , Elham N. Bifari, Aisha R. Al-Marhabi, Fatimah A.M. Al-Zahrani , Huda A. Al-Ghamdi , Sameera N. Al-Ghamdi, Abdullah M. Asiri , Reda M. El-Shishtawy

The Suzuki-Miyaura cross-coupling reaction was utilized for the synthesis of 15 new compounds containing phenothiazine (PTZ), phenoxazine (POZ), carbazole (Cz), and triphenylamine (TPA) as good electron donors. The synthesized compounds were furnished with active carbaldehyde groups and decorated with phenyl, thienyl, furyl, imidazolyl, or oxadiazolyl units linked to either one or two sides of the central cores (PTZ, POZ, and Cz). A simple catalytic systems based on Pd(PPh3)4 were tried and the results showed better C–C coupling efficiencies of the electron-rich phenothiazine halides over phenoxazine and carbazole analogues when coupled with either electron-rich or electron-deficient boronic acid precursors. Besides, the coupling process of substituted phenothiazine halides with different boronic acids precursors, based on phenyl (Ph), furyl (Fu) and thienyl (Th) units, was found to be dependent on the electronic nature of both PTZ-halide and boronic acid precursors. Coupling efficiency of Ph, Fu, and Th rings with the skeleton of imidazolyl-PTZ-Br coupler to bring up compounds 6a-c showed the order: Ph>Fu>Th (with the yield of 86, 85, and 80%, respectively), while coupling efficiency of the brominated PTZ-oxadiazolyl-phenyl coupler with different arylboronic acids showed the order of Th>Ph>Fu to obtain compounds 8a-c. Additionally, the TPA derivative 11b was obtained with an excellent yield of 96% using Pd(PPh3)4 . The successful activation of the synthesized derivatives with carbaldehyde groups and the integration of different spacers made them substantially suitable to be exploited as promising intermediates for the future synthesis of versatile π-conjugated systems.

الجمعة 01/سبتمبر/2023

Determination of metanil yellow dye in turmeric powder using a unique fluorescence Europium doped carbon dots

Mohamed A. Abdel-Lateef , Marzough Aziz Albalawi , Sameera N. Al-Ghamdi, Wael A. Mahdi , Sultan Alshehri , Mohamed A. El Hamd

Turmeric, a spice known for its therapeutic benefits, is a major source of curcumin which is a polyphenol with anti-inflammatory properties. It aids in treating arthritis, anxiety, metabolic syndrome, liver disease, hyperlipidemia, and inflammatory diseases. In this study, a novel fluorescence probe was designed to detect the adulteration of curcumin by metanil yellow (a harmful artificial dye). The probe was synthesized from the carbonization and conversion of the Tannic acid-Eu3+ complex to bright fluorescence Eu-carbon dots in the presence of orthophosphoric acid. The size, morphological, and optical features of the formed Eu-carbon dots were characterized by UV, SEM, TEM, and FTIR techniques. Furthermore, the formed Eu-carbon dots possess unique fluorescence excitation and emission features at 307.5 nm and 340.6 nm, respectively. These fluorescence features can be successfully quenched upon the addition of metanil yellow dye. The value of quenching in the fluorescence intensity of the Eu-C-dots was directly proportional to the dye’s concentration. The LOD value for the proposed method was 0.390 µg/mL with a linear range of 1.0–15.0 µg/mL. Furthermore, the methodology exhibited good recovery values for determining the studied dye without any interference from the presence of curcumin

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هذه الصفحة هي خدمة مقدمة من جامعة الباحة - عمادة التعلم الإلكتروني وتقنية المعلومات لمنسوبي الجامعة من أعضاء هيئة التدريس والموظفين. جميع الآراء والمدخلات الواردة في هذه الصفحات تعبر عن رأي كاتبها فقط، ولا تعبر بالضرورة عن رأي جامعة الباحة.