Background: Citrus sinensis (L.) Osbeck peels are usually discarded as wastes; however, they are rich sources of Vitamin C, fibre, and many nutrients including phenolics and flavonoids which are also good antioxidant agents. This study aimed to examine phytochemical composition, antioxidant capabilities, cytotoxicity of C. sinensis (L.) Osbeck peel extract and and to compare the antibacterial activity with zinc nanoparticles of Citrus sinensis (L.) Osbeck peels with its extract. GC-MS analysis of the compounds present in the peels extract of Citrus sinensis (L.) Osbeck was also done. Methods: C. sinensis (L.) Osbeck fruits were collected from Sindhuli district and were taken to National Herbarium and Plant Laboratory, Godawari, Lalitpur for its identification. Extraction was done by maceration in aqueous solvent. Extract was subjected to Phytochemical screening done by color reactions with different reagents, Antioxidant activities of the peel extracts were examined via the 2,2-diphenylpicrylhydrazyl (DPPH) free radical scavenging activity. Total phenolic content and total flavonoid content of the extracts were measured via the Folin-Ciocalteau method and the aluminium chloride colorimetric method, respectively. Cytotoxic activities of the peel extracts were determined by Brine Shrimp Lethality Bioassay. Comparison of antibacterial activity of extract and zinc oxide nanoparticles prepared via green synthesis using C. sinensis (L.) Osbeck peel extracts as reducing agents. Antibacterial activity was tested by Bore well diffusion method. Result: The extractive value of C. sinensis (L.) Osbeck was found to be 8.64% in aqueous solvent. GC-MS analysis of peel extract of C. sinensis (L.) Osbeck showed the presence of 2-Methoxy-4-vinylphenol, 4H-Pyran-4-one, 2,3-dihydro-3,5-dihydroxy-6-methyl, Benzoic acid, 3-Deoxy-d-mannoic lactone and 5-Hydroxymethyl-furfuralas major compounds. The qualitative phytochemical test showed the presence of tannin, alkaloid, carbohydrate, flavonoid, cardiac glycoside, terpinoid. The DPPH radical scavenging activity of C. sinensis (L.) Osbeck peel extract was 35.56 microgram/ml. TPC of C. sinensis (L.) Osbeck peel extracts was 46.07 mg GAE/g. TFC was 1.29 mg QE/g. The LD50 value of Brine Shrimp Lethality assay of the extract showed 312.5 microgram/ml which is indicative. The antibacterial activity of zinc oxide nanoparticles was found to be greater than that of the extract, but the antibacterial activity of Zn-NPs was less than that of the standard. Conclusion: Hence, the GC-MS analysis of aqueous extracts of leaves of C. sinensis (L.) Osbeck showed the presence of 20 different compounds. Phytochemicals including phenolics and flavonoids in C. sinensis (L.) Osbeck peel extracts exhibited good antioxidant properties. The extract also exhibited antibacterial activity which was 4 times less than that of the standard. The antibacterial activity of standard was 2 times greater than that of Zn-NPs. The extract also exhibited cytotoxic activity. This study indicated that C. sinensis (L.) Osbeck peels contained potential antioxidant, cytotoxic and antibacterial compounds which could be exploited as value added products.

中文翻译：

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柑桔奥斯贝克果皮提取物合成的氧化锌纳米粒子的表征与抗菌性能

背景：柑桔（O.beck）的奥斯贝克果皮通常作为废物丢弃；但是，它们富含维生素C，纤维和许多营养物质，包括酚类和类黄酮，它们也是很好的抗氧化剂。这项研究的目的是检查中华绒螯蟹（O.beck）果皮提取物的植物化学组成，抗氧化能力，细胞毒性，并比较柑橘（Osbeck）果皮及其提取物与锌纳米颗粒的抗菌活性。还进行了柑桔皮提取物中存在的化合物的GC-MS分析。方法：从信德利区采集中华绒螯蟹（Osbeck）的果实，并送往拉利特布尔戈多瓦里国家植物标本室和植物实验室进行鉴定。通过在水性溶剂中浸渍进行萃取。通过与不同试剂的显色反应，对提取物进行植物化学筛选，通过2,2-二苯基吡啶甲基肼基（DPPH）清除自由基的活性检查果皮提取物的抗氧化活性。提取物的总酚含量和总黄酮含量分别通过Folin-Ciocalteau法和氯化铝比色法测量。果皮提取物的细胞毒性活性通过盐水虾致死率生物测定法确定。提取物和氧化锌纳米颗粒的抗菌活性比较，这些纳米颗粒通过绿色合成使用中华C（O.beck）奥斯贝克果皮提取物作为还原剂进行制备。通过孔扩散法检测抗菌活性。结果：在含水溶剂中，中华。的提取率为8.64％。中华绒螯蟹皮提取物的GC-MS分析表明，存在2-甲氧基-4-乙烯基苯酚，4H-吡喃-4-酮，2,3-二氢-3,5-二羟基-6-甲基，苯甲酸，3-脱氧-d-甘露糖内酯和5-羟甲基-糠醛主要化合物。定性植物化学测试显示单宁，生物碱，碳水化合物，类黄酮，强心苷，萜品醇的存在。C. sinensis（L.）Osbeck果皮提取物的DPPH自由基清除活性为35.56微克/毫升。C. sinensis（L.）奥斯贝克果皮提取物的TPC为46.07 mg GAE / g。TFC为1.29 mg QE / g。提取物的盐水虾致死率测定的LD50值显示为312.5微克/毫升，这是指示性的。发现氧化锌纳米颗粒的抗菌活性大于提取物的抗菌活性，但Zn-NPs的抗菌活性低于标准品。结论：因此，对中华C（C。sinensis（L.）Osbeck）叶片水提物的GC-MS分析表明存在20种不同的化合物。C. sinensis（L.）奥斯贝克果皮提取物中的酚类和类黄酮等植物化学物质具有良好的抗氧化性能。提取物还显示出比标准品低4倍的抗菌活性。标准品的抗菌活性是Zn-NPs的2倍。提取物还表现出细胞毒性活性。这项研究表明，中华绒螯蟹（Osbeck）果皮中含有潜在的抗氧化剂，细胞毒性和抗菌化合物，可作为增值产品加以利用。C. sinensis（L.）奥斯贝克果皮提取物中的酚类和类黄酮等植物化学物质具有良好的抗氧化性能。提取物还显示出比标准品低4倍的抗菌活性。标准品的抗菌活性是Zn-NPs的2倍。提取物还表现出细胞毒性活性。这项研究表明，中华绒螯蟹（Osbeck）果皮中含有潜在的抗氧化剂，细胞毒性和抗菌化合物，可作为增值产品加以利用。C. sinensis（L.）奥斯贝克果皮提取物中的酚类和类黄酮等植物化学物质具有良好的抗氧化性能。提取物还显示出比标准品低4倍的抗菌活性。标准品的抗菌活性是Zn-NPs的2倍。提取物还表现出细胞毒性活性。这项研究表明，中华绒螯蟹（Osbeck）果皮中含有潜在的抗氧化剂，细胞毒性和抗菌化合物，可作为增值产品加以利用。