**1. Introduction**

Ever since our ancestors, humanity has been dependent on the consumption of plants as a source of food, health, and for construction/ornamental. In addition, plants have developed a complex defense system against biotic and antibiotic stress: therefore, they can produce diverse secondary metabolites (SMt). The stress to which plants are submitted under natural conditions is caused by different factors, among

which stand out: attack by diverse insects and/or microorganisms (viruses, bacteria, and fungi) competition for soil, light, and nutrients, and exposure to sunlight [1].

SMt are compounds that do not play a fundamental role in the vital processes of plants, but they are important as mechanisms of defense. They are responsible for organoleptic and protective properties, such as odor, flavor, color, and consistency. These SMt also act as chemoattractants or chemorepellents. In addition, they are of great interest in industry for the preparation of food additives, agrochemicals, essences, biodiesel, narcotics, insecticides, cosmetics, and aromatics, and one of the most important of these is for the production of substances with pharmaceutical interest. Frequently, the production of SMt wild-collected plant is very low (less than 1% of the plant's Dry Weight -DW-), and this depends specifically on the plant's physiological state, the geographic location, the climate, among other factors [2].

Due to the low yield of SMt in wild plants and considering its important biological activity, alternatives or tools are currently being sought to increase its yield. One of these alternatives is the application of several biotechnology processes, a discipline that is oriented toward the development and innovation of technologies that involve the management of biological material for the production of a good or service [3].

One of the advantages in the use of biotechnological processes is to increase the production of bioactive SMt and also reduce the production time, which favors their availability [4]. The purpose of this paper is to summarize all the information that exists on the use of biotechnological processes for the production of bioactive compounds from Mexican medicinal plants.

### **2. Products with pharmaceutical importance**

Plants constitute a huge reservoir of chemical structures, the most economically important are medicinal plants, due to their diverse biological activities; which over the years have favored human survival thanks to their use in Traditional Medicine (TM) [5–7]. TM is widely used in some developing countries, where their health system is still growing and is of great economic importance. In Africa, up to 80% of the population employs TM to help satisfy its health needs. In Asia and in Latin America, the populations continue to use TM because of historical circumstances and cultural beliefs. In China, TM is of great importance due to the large percentage of population that utilizes it, being higher than 60%. In some developed countries, the percentage of the population that uses TM is 48% in Australia, 70% in Canada, 42% in the USA, 38% in Belgium and 75% in France [8].

Currently, Medicinal Plants (MP) are employed by 80% of the world population; therefore, these are overexploited not only because are source of active ingredients, also due to the high nutritional, wood, cosmetic, agricultural, and/or medicinal value that many of these have. For example, it is estimate that China exports 120,000 tons of MP and India, some 32,000 tons while Europe imports 400,000 tons of MP. This leads to overexploitation of the species and many of them are in danger of extinction [9, 10].

The World Conservation Union and the World Nature Fund report that there are between 350,000 and 550,000 species of MP in the world, of which only approximately 20% possess documented investigation of their biological potential, and nearly 15,000 species are in danger of extinction due to the overexploitation and destruction of habitats [10, 11].

#### *Modulation of Secondary Metabolites among Mexican Medicinal Plants by Using Elicitors… DOI: http://dx.doi.org/10.5772/intechopen.99888*

Nowadays, scientific interest in MP has increased due to the high costs and adverse effects that allopathic drugs cause, in addition to the increasing appearance of strains of microorganisms that are resistant to current treatments [12–14]. It is noteworthy that almost 25% of the active principles of allopathic drugs currently used were isolated and/or semisynthesized from plants [9]. In modern medicine, digoxin is use as a cardiotonic and was isolated from *Digitalis purpurea* (purpura, its common name); escin is use as an anti-inflammatory and venotonic and was isolated from *Aesculus hippocastanum* (its common name, horse chestnut). Another compound utilized is ajmalicin, employed for circulatory disorders, and was isolated from *Rauwolfia serpentina*; paclitaxel (an anticancer drug) has been semisynthesized by Bristol-Myers Squibb since 2002, and was obtained from the compound 10-deacetylbacatin III, it was obtained from the cell suspension of the *Taxus baccata.* While diosgenin, a steroidal sapogenin, was obtained from the tubercules of several *Dioscorea* species, which was the raw material for the semisynthesis of progesterone [15].

Guanidine is a natural product with good hypoglycemic activity that was isolated from *Galega officinalis* (L); however, this compound has been reported to be toxic for human consumption. Therefore, this compound was semi-synthesized obtaining metformin (dimethylbiguanide), which is less toxic and has a pharmacologic effect similar to the original molecule and is widely used for the treatment of type II diabetes mellitus. It is worth noting, due to the high demand for SMt on the market; several companies have seen the need to discover novel sources of raw material from MP [16].

On the other hand, at present, the use of medicinal plants and/or phytodrugs is very frequent. The phytodrugs are elaborate with plant material and some derivatives of this. The main ingredient is the aerial or subterranean plant's part; as well as extracts, tinctures, juices, resins, fatty acids, and essential oils presented in pharmaceutical form. The therapeutic effectiveness and safety have been confirmed scientifically [17]. Some examples of these include ginseng, it is obtained from Panax genus (*Panax ginseng* and *P. quinquefolium*) native from Asia and America, respectively. The main biological effect of ginseng "tonic" phytodrug is that it possesses the ability to increase the capacity to tolerate tensions, which leads to increased mental and physical yield. Another phytodrug obtained from St. John's wort (*Hypericum perforatum*) is Hiperikan, which is standardized based on its content of hypericin; its principal pharmaceutical use is against depression. *Ginkgo biloba* (Ginkgo) belongs to the Ginkgoaceae family, the active compounds in the leaf's extracts are gingolides (gingolides A-C, J, and M), along with a mix of sesquiterpene lactones and flavonoids which is used against depression. The majority of commercial preparations from Ginkgo are standardize with approximately 5–7% of terpenic lactones and 22–27% of flavonoids and they are employed mainly for the treatment of the cognitive deterioration associated with alterations in blood circulation in the brain, such as dementia. The phytodrug elaborated with *Echinacea purpurea* is commercially known as EchinaCold (Schwabe Pharma) or Immulone (ATOS Pharma). These are standardized on based of the echinacosides (caffeic acid derivative) content, whose main biological effect is as an immunostimulant [18]. In Oceania region, the extract from *Piper methysticum* (from root and rhizome) has the commercial name Kava-kava (with 30% of kava lactones), and is utilized for their neurotransmitter activity [19]. Another phytodrug is Vitango, obtained from *Rhodiola rosea* (with 3.5% rosavins and 1% salidrosides), and it is employed for reducing the stress associated with physical and mental tasks [20]. Plantival has extract mixture from *Valeriana officinalis* (160 mg) and *Melissa officinalis* (80 mg) and is use in the treatment of nervousness, restlessness and insomnia as an anxiolytic and antidepressive [21]. Another phytodrug, known as

Prostasan, is the extract of *Serenoa repens*, standardized at 25% of fatty acids; the dose employed is 160 mg, and its principal effect is antiandrogenic and against benign prostatic hyperplasia [22].

Due to the acceptance and growing use of phytodrugs around the world, PM are raw materials of great attention due to high consumption. In addition, MP biosynthesize several bioactive compounds, which are classified as terpenoids, alkaloids, lactones, flavonoids, coumarin, lignans and phenols, among others; many of these have restrictive taxonomical distribution. Although the SMt functions are not directly associated with the plant's basic function, these compounds carry out some interaction roles in the plant and its environments such as: protection against pathogens, protection against abiotic tensions (ultraviolet radiation radiation), they possess the function of attracting pollinating insects, and they are signaling molecules and active ingredients for drugs [23–25].

It is estimated that around 50% of the drugs approved by the Federal Drug Administration are products derived from natural sources or analogs deriving from plants or microorganisms [26]. However, raw material can be limited, and its exploitation is one of the main ecological concerns. One of the key objectives of plant biotechnology is the development of large-scale production methods of pharmacologically active products. Additionally, the massive biosynthetic potential of plants has not been completely exploited yet and biotechnology can be employed to generate new chemical compounds that possess unknown biological activities and/or with a different mechanism of action, or a better one, than those in existence [23].
