Stevia: Pharmacology and toxicology of stevioside, rebaudioside A, and steviol

Of the three compounds to be discussed in this post, stevioside and rebaudioside A are major natural glycosides found in the leaves of S. rebaudiana (henceforth in this chapter expressed as Stevia), while the aglycone, steviol is a biosynthetic precursor in the leaves and a putative mammalian metabolite of stevioside. These compounds are structurally related to ent-kaurenoic acid. Stevia leaves contain naturally high levels of the glycosides, and selective breeding has increased these levels further. Typical concentrations range from 5 to 10% w/w of the dried leaf for stevioside, 2–4% for rebaudioside A, 1–2% for rebaudioside C, and 0.4–0.7% for dulcoside A. Newer, commercially developed strains may contain an excess of 14% diterpene glycosides. Stevioside, in the form of the pure compound or of Stevia leaf extracts, has been widely used as a food additive, particularly in Brazil, Korea and Japan. It has been estimated, e.g. that somewhere between 85 and 170 metric tons of stevioside were consumed in Japan in 1987. This is equivalent to approximately 1,700 tons of leaf. The absence of reports of adverse reactions from these countries is primafacie evidence of lack of gross toxicity. Safety concerns, therefore, Read more […]


Importance and Distribution of the Genus The genus Stephania (Menispermaceae) comprises approximately 50 species distributed from Africa through Asia to Australia. The importance of the genus in traditional medicine in Asia and Africa is well documented. The underground tubers of the vines are generally characterized by powerful pharmacological effects. Stephania abyssinica is a creeper indigenous to southern and eastern Africa. The leaves of this plant are used as a purgative and emetic, whereas the roots are employed in the treatment of roundworm, menorrhagia and boils. Stephania bancroftii is used by the aboriginal communities of Australia both as a treatment for diarrhea and as a fish poison. Stephania cepharantha (), a perennial plant native to mainland China known by the vernacular name “bei-yan-zi”, is commonly used as a folk medicinal herb. Decoctions from the tuber of Stephania cepharantha are traditionally used in China to treat a number of diseases including parotiditis, gastric ulcer, leukopenia, alopecia areata and alopecia androgenetica. The major components of this crude drug, known as Cepharanthin preparations, are the bisbenzylisoquinoline (BBI) alkaloids cepharanthine, isotetrandrine and cycleanine. Stephania Read more […]

Bioactivity of Basil: Other Activities

Plants belonging to the genus Ocimum exhibit a great deal of different pharmacological activities of which the most important, as concluded by the number of research reports, will be discussed below. The activities to be discussed in more detail are anti-inflammatory, immunomodulating and adaptogenic, anticarcinogenic, hypoglycemic and blood lipid lowering, radioprotective, effect on the CNS, antiulcerogenic, hepatoprotective and the effect on smooth muscle. In addition to these activities a number of other activities are also reported in the literature, such as antioxidant, angioprotective effect, effect on the reproductive behaviour and antiwormal activity. Anti-inflammatory Activity Ocimum sanctum L., popularly known as “Tulsi” in Hindi and “Holy Basil” in English, is a widely known sacred plant of Hindus. Different parts of the plant have been claimed to be valuable in a wide spectrum of diseases. For instance, it is used for the treatment of arthritis, rheumatism, pain and fever in the Ayurvedic system of medicine. Ocimum sanctum is now intensively studied in order to prove these activities by pharmacological evidence. A methanol extract and an aqueous suspension of Ocimum sanctum leaves inhibited Read more […]

Stevia rebaudiana (Bert.) Bertoni

Stevia rebaudiana (Bert.) Bertoni is a small perennial shrub of the Compositae family. Estimates of total number of species in the genus ranges from 150 to 300, all distributed in the New World, from the southwestern United States to the northern Argentina. The native occurrence of Stevia rebaudiana is between 22-24° S and 53-56° W, in Paraguay and Brazil. This species was known by the Guarany Indians under several names (Caa-jhe-he, Caa-hee, Ca-a-yupe, Azuca-caa, Eira-caa) related to its sweet leaf taste and to its use in sweet beverages and remedies, especially the cooked “mate” (Ilex paraguariensis). Stevia rebaudiana became known by the Europeans due to its discovery by Moises Bertoni in 1899; the chemist Rebaudi was the first to study its chemical characteristics. Stevia rebaudiana: Economic Importance and Uses The economic importance of this species is the consequence of the presence, in the leaves, of substances with high sweetening power, whose physical, chemical, pharmacological and toxicological characteristics allow its use in human diet as natural and diethetic sweetening, with no colateral effects. Several reviews about this plant have been published over the past 40 years, including topics like its Read more […]

Althaea officinalis L. (Marshmallow)

Habit and Distribution of the Plant The genus Althaea belongs to the family Malvaceae and includes 12 species, which are located mainly in Europe, with the exception of the Scandinavian countries, and the Near East (western and north Asia). They are cultivated mainly in Germany, France, Belgium, Spain, Italy, Hungary, and Russia, and have been introduced in North and South America. The most important species of the genus is Althaea officinalis L. (marshmallow), densely gray-pubescent perennial up to 1.5-2 m, with stellate hairs. Leaves triangularovate, acute, crenate-serrate, undivided or palmately 3-5-lobed, often somewhat plicate. Flowers solitary or clustered in axillary inflorescences shorter than the substanding leaf. Epicalix segments linear-lanceolate. Sepals ovate, acute, curved over the fruit. Petals, 15-20 mm, very pale, lilac-pink, rarely deeper pink. Anthers are purplish red. Mericarps more or less densely covered with stellate hairs. The chromosome number is 2n = 42. The plant has a woody rootstock from which numerous roots arise, up to 30 cm in length. The roots (Radix Althaea naturalis and mundata); the leaves (Folia Althaeae), and the flowers (Flores Althaeae) are used in medicine. Marshmallow Read more […]

Asteraceae: Drug Interactions, Contraindications, And Precautions

Patient survey data from Canada, the U.S., and Australia show that one in five patients use prescription drugs concurrently with CAM. The inherent polypharmaceutical nature of complementary and alternative medicine increases the risk of adverse events if these complementary and alternative medicine either have pharmacological activity or interfere with drug metabolism. Since confirmed interactions are sporadic and based largely on case reports, advice to avoid certain drug-CAM combinations is based on known pharmacological and in vitro properties. Known Hypersensitivity to Asteraceae Cross-reactive sesquiterpene lactones are present in many, if not all, Asteraceae. Patients with known CAD from one plant may develop similar type IV reactions following contact with others. Affected patients are often advised to avoid contact with all Asteraceae, yet this advice is based on limited knowledge of cross-reactivity between relatively few members of this large family. Some authorities recommend avoiding Asteraceae-derived complementary and alternative medicine if, for example, the patient is known to have IgE-mediated inhalant allergy to ragweed. While a reasonable approach, this ignores a number of important facts: (1) Read more […]

Fenugreek (Trigonella Foenum-Graecum)

Medical Uses Fenugreek has been used to lower blood glucose levels in diabetics and to lower high cholesterol and blood lipid levels. It has also been used to increase fiber in the diet, to reduce inflammation, and to aid digestion. And it has been used for bronchitis and loss of appetite. Historical Uses In folklore, fenugreek was said to stimulate milk production and increase appetite. It has been used traditionally to lower blood glucose levels in diabetic patients. In India it has been used as a condiment. Growth This annual plant grows in the Mediterranean region. Fenugreek: Part Used • Seeds Major chemical compounds • Steroidal saponins • Mucilage • Alkaloid trigonelline • Flavonoids Fenugreek: Clinical Uses Fenugreek has been used to lower blood glucose levels in diabetics, to increase fiber in the diet, to reduce inflammation, and to aid digestion. It has also been used for hypercholesterolemia, hyperlipidemia, bronchitis, and loss of appetite. It is approved by the German Commission E for “loss of appetite and external use as a poultice for inflammation”. Mechanism of Action Fenugreek contains soluble fiber that indirectly decreases blood glucose. Its anti-inflammatory and Read more […]

Horehound, White (Marrubium vulgare)

Horehound: Medical Uses Traditional use has been for bronchitis and respiratory illness with a nonproductive cough. Historical Uses In folk medicine, horehound has been used primarily for expelling worms; stimulating menses; and treating cough (horehound drops), dog bites, and fevers. In Egypt, horehound was known as “Eye of the Star”. Growth A member of the mint family, horehound has hairy leaves and stems. It grows in the United States and Europe and likes sandy soil, warmth, and sun. It can be planted by seed or cuttings. Harvest horehound leaves to about 4 inches above the ground before flowering. Parts Used • Dried leaves • Flowering tops Major Chemical Compounds • Marrubin • Bitters • Mucilage • Tannins Horehound: Clinical Uses Traditional use has been for bronchitis and respiratory illness with a nonproductive cough. Horehound also may have a hypoglycemic effect. It has been approved by the German Commission E for “loss of appetite, bloating and flatulence”. Mechanism of Action This herb’s bitterness aids digestion. It also exerts expectorant, antispasmodic, and antinociceptive (decreasing painful stimuli) effects by an unknown mechanism, but it is not known if horehound Read more […]

Maitake Mushroom (Grifola frondosa)

Maitake Mushroom: Medical Uses Maitake mushroom is used for anticancer effects, stimulation of the immune system in cancer patients, and as supportive therapy for patients undergoing chemotherapy or patients with HIV or AIDS, high blood pressure, hyperlipidemia, weight loss, or diabetes. Historical Uses The maitake is known as the “hen of the woods” and is valued for “maintaining health and promoting longevity”. Growth This mushroom is cultivated in Japan and native to the northeastern part of that country. Part Used • Edible mushroom Major Chemical Compound • D-fraction, a polysaccharide Maitake Mushroom: Clinical Uses Maitake mushroom is used for anticancer effects, immune stimulation in cancer patients, and adjunct therapy for patients undergoing chemotherapy. It is also used for patients with HIV and AIDS, high blood pressure, hyperlipidemia, weight loss, or diabetes (Natural Medicine, 2000). Mechanism of Action The D-fraction of beta-glucan has been shown to possess antitumor activity. It also lowers blood glucose and reduces weight in rats. It has immunostimulant effects (Natural Medicine, 2000). The most recent maitake extract is the MD-fraction, which, combined with the D-fraction, is helpful Read more […]


Very little information about plant use in Africa has been written down. In African thought, all living things are believed to be connected to each other, to the gods, and to ancestral spirits. If harmony exists between all of these, then good health is enjoyed, but if not, misfortune or ill health will result. Forces can be directed at humans by displeased gods, ancestors, and witches, resulting in disharmony which must be resolved before good health can be restored. Treatment may also involve much more than medicine. Practices such as divination and incantation maybe carried out to help with diagnosis, and sacrifices may need to be made in order to placate the supernatural entity. The traditional healer is also likely to be a religious leader, since health and spirituality are closely intertwined in Africa. Traditional healers have existed throughout Africa since prehistoric times, for example, the ifas and juju men of West Africa or the inyanga (sangoma is the term used for diviners) of South Africa. Various methods have been used to identify “healing plants,” such as trying to find a plant that possesses a stronger spirit than the one causing the disease, or by using the “law of signatures.” This system existed Read more […]