Distribution and Importance of the Plant
Solanum chrysotrichum (Schldl.) of the Solanaceae family belongs to a group of plants commonly known as “sosas” throughout the highlands of Chiapas, Mexico. These plants are used for the treatment of dermatological infections and other skin ailments. Among this group, and as a result of extensive ethnobotanical investigations, two species, Solanum chrysotrichum and S. lanceolatumy are particularly noted, as revealed by the highest index of citation. The two species are described by traditional healers as the most effective herbal remedies for the treatment of skin infections. According to popular nosologies considered as “skin infections”, water extracts from the leaves of S. chrysotrichum constitute the specific treatment for tinae (tirlapedis), scabies and other mycosis.
S. chrysotrichum is distributed in the states of Chiapas, Hidalgo and Michoacan, in Mexico, where names such as sosa, berenjena and cuxpeal are given to this plant respectively. Among the highland Mayas of Chiapas, it is known as “kitxpeul” in tzotzil, “k ‘uxbal chix” in tzeltal, and “pajutiek” in chol. It is an erect perennial herb which may grow up to 2 m in height, with spiny stems. The leaves are rough to the touch, 20-30 cm long and 10 cm wide, covered with reddish, rigid, large hairs, and deeply divided margins. The flowers are white with a star appearance. This plant normally grows at roadsides in temperate weather.
Data given from the healers of Chiapas on the herbal medication of S. chrysotrichum, indicated that the fresh leaves from the plant are boiled in water, and administered topically as plasters or poultices. However, sometimes the infusions are given orally, or as douches.
Initial pharmacological investigations with S. chrysotrichum leaves were performed using organic solvent extracts from the plants collected in Chiapas. The extracts were evaluated for their ability to inhibit the in vitro growth of several Gram positive and Gram negative bacteria, as well as the yeast Candida albicanSy and the dermatophyte Microsporum gypseum. The MIC (minimal inhibitory concentration) values from the plant extracts against the last two microorganisms were promising, since these pathogens show some resistance to actual prescribed drugs. In another series of studies, the activity of the extracts was specifically evaluated against the main causative agents of athlete’s foot: Tricophyton mentagrophytes, Tricophyton rubrum and Microsporum gypseum, exhibiting important antifungal actions against the three dermato-phytes in culture.
A pilot clinical study using organic extracts from the leaves of S. chrysotrichum was conducted at the Mexican Social Security Institute (Regional Hospital of Cuernavaca Morelos, Mexico). A group of 18 ambulatory patients with diagnosis of tina pedis (mainly produced by Tricophyton mentagrophytes) was selected and treated with a cream containing 5% of the methanolic extract of the leaves, which was applied topically twice a day during 4 weeks of treatment. A similar number of infected patients were considered as a control group, and treated with miconazole that was applied in the same way. The results showed that after 1 week of treatment, 42% of the patients receiving the plant extract recovered, while no cure was observed with miconazole during the same period. Remission of the symptoms was observed in both groups at the end of each complete treatment.
Solanum chrysotrichum (Schldl.): Conclusion and Prospect
From traditional medicine knowledge, it was possible to select a plant species used to treat skin mycosis. The pharmacological value of this plant was demonstrated, and we were able to purify and isolate an antifungal spirostanol saponin named SC-1, which represents a new molecule. The in vitro-presented experiments demonstrate that the establishment of cell suspension cultures from Solanum chrysotrichum is able to produce SC-1 with higher yields than those obtained for wild plants. Even though S. chrysotrichum is widely used as a popular medicine and grows in a very limited region in Mexico, the plant has never been cultivated, and the biotechnological approaches described herein, could allow the permanent and controlled production of the antifungal medicine. The cell suspension cultures of this plant were scaled to 101, demonstrating that the airlift bioreactors, that were used for this purpose, were adequate. The productivities were higher at a 10-1 volume, and increased by 60% when using a draw-fill mode in the bioreactor. The obtained productivity values in bioreactors are within those that had been considered promising for other plant species. The results with the in vitro culture systems of S. chrysotrichum are feasible alternatives for the bioproduction of SC-1. These procedures demonstrate, for the first time, the production of an antimycotic chemical for human use in bioreactors, from an important popular plant remedy.
Selections from the book: “Medicinal and Aromatic Plants XII” (2002).