# State-of-the-Art and Opportunities for Bioactive Pentacyclic Triterpenes from Native Mexican Plants
## 3 Opportunities, Limitations, and Future of Pentacyclic Triterpene Research in Mexico  
In the present review and analysis of the existing research about PCTs in Mexico, several conclusions and reflections were obtained. Derived from Mexican biodiversity, PCTs belonging to the oleanane group are mainly found in Mexican flora. According to the analyzed information, the greatest area where this class of compounds has been found is the southwest of Mexico, which is related to the richness and diversity in this zone. In this sense, many reports agree with the potential of PCTs (both at national and international levels) as antimicrobial agents and as a therapeutic option to deal with metabolic disorders such as diabetes and hypertension [7] or severe diseases such as cancer [4]. In research matters, PCTs have mostly been assayed for their antimicrobial activity in in vitro studies, but some reports of in vivo studies for the detection of anti-inflammatory effects were also found. In the same way, identification, characterization, and elucidation structure studies have limited access but in a more minor grade than biological activity testing. These observed trends are associated with the infrastructure and resources available in Mexican research centers where experimentation was carried out. In general, national institutions lack the equipment and budget for bioassays or characterization because these activities require special facilities and maintenance. Since only a few academic institutions own some of these facilities, many collaborations with these universities can be identifiedin the reviewed works. This limited national infrastructure explains the scarcity of testing for anticancerogenic activity when compared to other observed international efforts. Drug delivery formulation of these compounds has practically been null in Mexico, as observed in the corresponding section, and international collaborations have made the generation of PCT emulsions possible. In the same way, this behavior is related in part to the equipment deficiencies mentioned previously but also with an abandonment of this research line at a national level and more closely to the current national pharmaceutical policy (regulation and centralization). This last aspect is exemplified with the reported 29% acceptance rate of new drug applications in 2018 by social security institutions [57]. An alternative for encouraging drug delivery development in the future may be the search for synergies with the local industry, public health institutions, and government. An area of opportunity in the extraction and purification field of PCTs in Mexico is the implementation of novel and current sustainable green techniques (i.e., supercritical fluid extraction, microwave-assisted extraction, ultrasound-assisted extraction, pressurized liquid extraction) coupled with the use of green solvents (i.e., deep eutectic, ionic, water, etc.) [58], with the goals of more environmentally friendly and sustainable processes, energy savings, and reduced formation of toxic effluents [59]. This \"green process vision\" not only would have an acceptable ecological impact but would also stimulate the interest of the private sector to increase investments and consequently the facilities in research centers. Some researchers have started to take this approach, as in pristimerin recovery with the use of green solvents [60] and the evaluation of process \"greenness\" [61]; however, the focus is incipient. Undoubtedly, as mentioned in the introduction, there are still a wide number of Mexican plants that have not been studied and may contain novel or already reported PCTs. Plants are a valuable natural resource for treating diseases that affect every person around the world, solving problems from a social perspective and, at the same time, reaffirming and highlighting part of the cultural heritage of our country.