7. Conclusion

In our opinion, step 3 represents the main lack of evidence in order to develop a natural sunscreen product. Despite an improving number of recent studies regarding the incorporation of antioxidants into sunscreen [25, 27, 28], none of the researches we reviewed include herbal products and more sophisticated formulations, as nanostructured lipid carrier, elastic niosomes, nanoparticles, microemulsion, etc. We recommend this way as an essential trend for

Scientific reports directed to the discovery of novel natural photoprotective ingredients often describe only the UV-filtering activity (step 1), which is a necessary but not sufficient condition to support the speculation of the effectiveness if inserted into a sunscreen tested on volunteers. The same issue can be referred to the in vitro bioactivity studies (step 2). The hardest challenge is to enhance the already approved findings as models, mentioned in step 3. An extract or natural compound needs to be fully characterized also for its effect in humans in the final product. Without this, it will remain restricted to a scientific investigation, which will be seen as useless to understand the potential of application in substitution of synthetic or mineral filters. Finally, in order to demonstrate real "green" claims, we recommend completing the product development with aquatic ecotoxicity assay. This step is becoming quite relevant [31,

Natural extracts have often been used as a source of inspiration in the development of new drugs rather than drugs themselves. Thus, while the discovery of synthetic ingredients is based on a rational systematic approach, which takes into account "step-by-step" modifications driven by chemical-physical parameter, the approach to the discovery of herbal ingredients, to be used as extracts, is "experience driven" and mainly based on traditional uses. A step-by-step procedure applied to natural extract would imply (I) the preparation of extracts and eventually phytochemicals from herbs, (II) the phytochemical study of extracts of herbal preparation or compound isolation, (III) the structure/composition elucidation, (IV) the in vitro biological activity evaluation, (V) the compound characterization and principal activity inves-

Furthermore, on the one hand, a central government agency of countries with high biodiversity should consider establishing research projects that involve ecological ethics, such as the managing, care, and preservation of the environment. However, on the other hand, the discovery of such ingredients could lead to improving agriculture or farming of these plants which may become an important job opportunity, especially in countries where the land is not favorable for the traditional farming. Finally, biotechnology in fields of plants is already a precious source of ingredients (i.e., secondary metabolites), which can be obtained from cell culture rather than traditional farming, thus saving biodiversity and land to be dedicated to plants for food. This has already been proven possible in the field of medicinal plants (i.e.,

6. Natural extracts as a source of active compounds: from ancient

32] and could be a significant benefit for a new sunscreen product.

tigation, (VI) and the in vivo proof of the in vitro elucidated activities.

"green" sunscreen research.

to modern times

54 Herbal Medicine

Artemisia annua) [33].

In this chapter, we presented a systematic approach based on our experiences and proposed it as a possible standard approach in this field. The steps mentioned in Figure 1 have to be considered as an initial set of guidelines needed for the development of herbal-based sunscreen. The end result is a complete and rational methodology for the research and development of herbal sunscreen. The authors consider it to be essential to match the initial in vitro studies about UV filter activities with synergic biological activities (antioxidant, anti-inflammatory, inhibitory UVinduced damage effect, etc.) and formulation strategies (boosters, encapsulation, etc.). A solid response in each step may be considered a complete strategy. Finally, regarding natural products and traditional knowledge, an eco-friendly and sustainable approach can complete the investigation process and the management of the industrial supply chains.

We believe that our contribution will be useful to expedite the discovery of sunfilters from herbs. With a solid discovery approach, chances of success will greatly increase.
