**13. Success stories**

**10. Enhanced activity**

360 Application of Nanotechnology in Drug Delivery

activity [71].

**11. Release profile**

production is increased [58].

**12. Enhanced stability**

Encapsulation of active compounds into nanocarriers improves their activity. This might be attributed to several factors such as enhanced solubility, better stability for both *in vivo* and *in vitro*, and better formulation. However, the better penetration of the introduced nano systems through cellular membrane via unique interaction mechanism is an additional factor that participate in enhancing the bioactivity of drugs encapsulated in nanocarriers. For example, *Origanum dictamnus* extracts are known to have antimicrobial and antioxidant properties due to the presence of considerable concentrations of pehnolic compounds like flavones and cumarines. Research showed that encapsulating this extract into liposomes improved its

Obtaining constant drug release is considered an urgent necessity to obtain sustained drug level in tumor tissue which can lead to a lower dose requirement. For example, paclitaxel gelatin nanoparticles are highly effective in the treatment of bladder cancer because the rate of paclitaxel release from paclitaxel gelatin nanoparticles is limited by the drug solubility in aqueous medium. So the drug concentration remains constant and does not dilute when urine

Sometimes, a fast release rate is desired, accompanied with enhanced solubility and penetra‐ tion of non polar drugs. For example, *Hibiscus rosa-sinensis* and *Murraya koenigii* extracts are acclaimed to prevent hair loss and promoting its growth. However, proving such claims scientifically was hindered by many limitations, especially the poor solubility of the extracts in water. Since the desired formulation is intended to be used as a topical treatment with fast release rate to study its effectiveness, microemulsions were the ideal choice for improving the

The instability of most phytochemicals in bio environments results in quick degradation and reduced activity. Encapsulation of such phytochemicals in carriers shields them from harsh conditions that lead to their decomposition. Quercetin has a life time of only five minutes in plasma whereas; quercetin loaded in liposomes modified with polyethylene glycol (PEG) has a life time of more than five hours in plasma [73]. Quercetin was also encapsulated in polymeric nanoparticles. Its antioxidant activity was maintained while its stability was highly enhanced when encapsulated in eudragit nanoparticles (polymeric nanoparticles). This polymeric nanoparticle protected quercetin and improved its stability in in acidic medium. However, the polymeric nanoparticles released the antioxidant under neutral to basic conditions, making

solubility and systemically study the extracts of these plants [72].

Nanotechnology is one of the most powerful tools in the modern life, as it has made a revo‐ lutionary impact in every aspect of human life. The speed by which nanomedicine has advanced-particularly through the utilization of the various types of nanoparticles in the prevention, diagnosis and treatment of many complex diseases like cancer-is fascinating. The world is starting to witness the benefits of the application of nanotechnology in the field of herbal/natural products' drug delivery. One such benefit is Abraxane®. This drug is consid‐ ered as a major success story of the nanomedicine approach to treat cancer [3]. Abraxane, an approved FDA drug, is a solvent free nano-version of the natural alkaloid, Taxol. Abraxane is both more effective and less toxic and has been successful in addressing the solubility problem associated with Paclitaxel (Taxol). Other examples of successful stories in the field of herbal drug delivery are the two companies Cosmetochem and Indena. Cosmetochem launched Herbasec® technology in the market. This product consists basically of liposomal encapsulat‐ ed, standardized botanical extracts that are used in cosmetics for their antioxidant effects for the prevention of aging. Examples also include liposomal preparations of various herbal constituents like extracts of White tea, Green tea, white hibiscus, Gurana and *Aloe vera*. Indena commercializes the plant constituents/extracts of liquorice (18ß-glycyrrhetinic acid), *Ammi visnaga* (visnadin), *Centella asiatica* (triterpenes), *Ginkgo biloba* (ginkgoflavonglucosides, ginkgolides, bilobalide), Hawthorn flower (vitexin-2″-O-rhamnoside), milk thistle (silymarin and Silybin), horse chestnut (escin ß-sitosterol), *Terminalia sericea* (sericoside), *Panax ginseng* (ginsenosides), grape seed (polyphenols) and Green tea (polyphenols) [75]. Moreover, a long list of recent patents on controlled release novel herbal formulations is becoming even longer [76] proving that nanotechnology for drug delivery is becoming the future of phytochemicals and opening the era for re-exploring and investigation the full potential power of traditional herbal medicine represented either by the herbal extracts and/or their pure isolated phyto‐ chemicals.
