Streblus asper is a well-known plant used in the Indian System of Medicine. In Ayurveda, the use of S. asper stem bark is recommended against elephantiasis for which there is no effective cure in the modern system of medicine. Besides this, folklore medicine also claims its use in cancer, ulcer, diarrhea, dysentery, toothache, etc. Research carried out using different in vitro and in vivo techniques of biological evaluation support most of these claims.
Filariasis, a disease of considerable public health importance, is a vector-borne helminthic infection occurring in tropical and subtropical regions of the world. Diethylcarbamazine (DEC) and ivermectin, the drugs used commonly for filariasis are insufficient because of their inadequate effect on the adult parasites. The high antifilarial activity of asperoside derived from the stem bark of S. asper against L. carinii, Brugia malayi and A. viteae in their respective hosts is unique as for the first time a cardiac glycoside has exhibited antifilarial activity. However, since the active antifilarial compounds are cardiac glycosides, they are sure to produce cardiotoxicity and thus it is necessary to dissociate the two activities. Attempts in this direction were made by the authors (50) by subjecting strebloside and asperoside to hydrogenation so as to reduce the α–β unsaturated lactone ring. The results showed that at a dose of 50 mg kg−1 orally, although there was a decrease in the macrofilaricidal activity exhibited by dihydroasperoside as well as dihydrostrebloside, but there was a marked absence of cardiotonic activity as compared to the parent compounds. Also the dihydro derivatives affected the reproductive ability of the female worms as they were found to be sterilized. A fraction, ‘Streblofil’, containing these two dihydro compounds was also prepared which also exhibited macrofilaricidal action as well as sterilized the female worms (51,52). Asperoside and strebloside were also found to be effective against S. cervi, the bovine filarial parasite. These studies give credance to the ethnomedicinal claims of S. asper being an antifilarial agent.
The branch of S. asper has been used as a tooth brush for strengthening teeth and gums (53). Studies have also proven that it exhibits selective bactericidal activity towards Streptococcus, especially to S. mutans which has been shown to be strongly associated with dental caries. Streblus asper extract thus has the potential for being used as a natural product for controlling dental caries. The anticancer principles have been identified as strebloside and mansonin. Besides, the volatile oil from the fresh leaves has also shown significant anticancer activity. Studies have shown that S. asper possesses cardiotonic, antimalarial, anti-allergic antitrypanosomal as well as insecticidal properties. It is, therefore, in itself a very important ethnomedicinal plant whose potential is yet to be scientifically exploited.
Presently there is an increasing interest worldwide in herbal medicines accompanied by increased laboratory investigation into the pharmacological properties of the bioactive ingredients and their ability to treat various diseases (54–56). Numerous drugs have entered the international market through exploration of ethnopharmacology and traditional medicine. Although scientific studies have been done on a large number of Indian botanicals, a considerably smaller number of marketable drugs or phytochemical entities have entered the evidence-based therapeutics. Efforts are therefore needed to establish and validate evidence regarding safety and practice of Ayurvedic medicines (57).