Several attempts have been made for green synthesis of metallic nanoparticles, revealing the significance of plant extracts in reducing metal source to nanoparticles and applications in various domains of science. Psidium guajava (guava) is evergreen, edible fruit-bearing plant, belonging to family Myrtaceae. Its leaves are reported to contain several phytochemicals like tannins, glycosides, terpenes, and triterpenes. This article focus on applications of Psidium guajava leaves extract in fabrication of nanoparticles of various metals like silver, gold, titanium dioxide, zinc oxide, and copper oxide. In respective research attempts, these metallic nanoparticles were evaluated for one or more applications like anti-microbial activity and/or photocatalytic activity. Use of polar extract of guava leaves indicated involvement of its polar phyto-compounds in reducing the metal source and stabilizing the nanoparticles. In conclusion, it could be noted that metal nanoparticles have better anti-microbial activity and photocatalytic potential over aqueous leaves extract.

中文翻译：

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番石榴叶辅助金属纳米粒子的绿色合成：综述

已经对金属纳米颗粒的绿色合成进行了多次尝试，揭示了植物提取物在将金属源还原为纳米颗粒方面的重要性以及在各个科学领域的应用。Psidium guajava（番石榴）是常绿、可食用的果树植物，属于桃金娘科。据报道，它的叶子含有多种植物化学物质，如单宁、糖苷、萜烯和三萜。本文重点介绍番石榴叶提取物在制备银、金、二氧化钛、氧化锌和氧化铜等各种金属纳米粒子中的应用。在各自的研究尝试中，评估了这些金属纳米粒子的一种或多种应用，如抗微生物活性和/或光催化活性。番石榴叶极性提取物的使用表明其极性植物化合物参与减少金属源和稳定纳米颗粒。总之，可以注意到金属纳米颗粒比水叶提取物具有更好的抗微生物活性和光催化潜力。