Silver Nanoparticles from Achillea fragrantissima: A Potent Weapon Against Cancer and Bacteria

The researchers found that these green-synthesized AgNPs exhibit strong cytotoxic effects, selectively targeting and killing human breast cancer (MCF-7) and liver cancer (HepG2) cells. Interestingly, the AgNPs were even more potent than the crude extract of the A. fragrantissima plant, with lower IC50 values (the concentration needed to kill 50% of the cells). The team also discovered that the AgNPs induce apoptosis, or programmed cell death, in the cancer cells by activating key genes like caspase-3, 8, and 9, while suppressing anti-apoptotic genes like Bcl-xL and Bcl-2.

But the benefits of these AgNPs don’t stop there. The researchers also found that they exhibit strong antibacterial activity against a range of Gram-positive and Gram-negative bacteria, including the notorious Achillea genus, belonging to the Asteraceae family, is a treasure trove of medicinal plants that have been used for centuries to treat a wide range of ailments. One particularly remarkable species is Achillea fragrantissima, a desert plant native to the Arabian Peninsula. This hardy plant has long been revered in traditional Arabic medicine for its potent anti-inflammatory, antispasmodic, and hepatoprotective properties.

The Green Synthesis of Silver Nanoparticles

In the latest study, researchers from King Saud University in Saudi Arabia harnessed the natural abilities of A. fragrantissima to synthesize a remarkable class of nanomaterials: silver nanoparticles (AgNPs). Unlike conventional chemical synthesis methods, the team employed a “green” approach, using the aqueous extract of the plant’s aerial parts as the reducing and stabilizing agent.

The process of AgNP synthesis was elegantly simple. When the A. fragrantissima extract was mixed with a silver nitrate solution, a striking color change from light yellow to dark brown was observed, indicating the successful reduction of silver ions (Ag+) to metallic silver (Ag0) nanoparticles. A series of advanced characterization techniques, including UV-Vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, and transmission electron microscopy (TEM), confirmed the formation of spherical AgNPs with an average size range of 16-22 nanometers.

Uncovering the Bioactive Compounds

The researchers delved deeper into the chemical composition of the A. fragrantissima extract, employing gas chromatography-mass spectrometry (GC-MS) analysis. Their findings revealed a diverse array of 20 different bioactive compounds, including the macrocyclic lactone (3E,10Z)-Oxacyclotrideca-3,10-diene-2,7-dione, the monoterpene alcohol (methylbuta-1,3-dienyl)-7-oxabicyclo [4.1.0] heptan-3-ol, and the sesquiterpene alcohol isolongifolol.

These phytochemicals likely play a crucial role in the synthesis and stabilization of the AgNPs, endowing them with their remarkable biological activities. The researchers also determined that the A. fragrantissima extract has a high content of phenolic compounds and flavonoids, which are known for their potent antioxidant and medicinal properties.

Potent Anticancer and Antibacterial Capabilities

The real standout feature of these green-synthesized AgNPs, however, lies in their impressive anticancer and antibacterial properties. When tested against human breast cancer (MCF-7) and liver cancer (HepG2) cell lines, the AgNPs exhibited a dose-dependent cytotoxic effect, with IC50 values (the concentration needed to kill 50% of the cells) as low as 17.2 and 14 μg/mL, respectively.

Further analysis revealed that the AgNPs induce apoptosis, or programmed cell death, in the cancer cells. They achieved this by activating key apoptotic genes like caspase-3, 8, and 9, while simultaneously suppressing anti-apoptotic genes such as Bcl-xL and Bcl-2. This selective targeting of cancer cells, while leaving healthy cells unharmed, is a crucial feature for the development of effective and safe cancer treatments.

But the benefits of these AgNPs don’t stop there. The researchers also evaluated their antibacterial activity against both Gram-positive and Gram-negative bacteria, including the notorious nanomedicine, this research stands as a shining example of the transformative potential of nature-inspired innovation. The discovery of these remarkable AgNPs from A. fragrantissima could pave the way for the development of new, highly effective cancer treatments and antimicrobial agents, ultimately improving human health and well-being.

Author credit: This article is based on research by Mashail Fahad Alsayed, Hissah Abdulrahman Alodaini, Ibrahim M. Aziz, Rawan M. Alshalan, Humaira Rizwana, Fetoon Alkhelaiwi, Sara Mohammed ALSaigh, Noorah A. Alkubaisi.

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