Artemisia: Plant Cultural Techniques

Plant Establishment Natural stands In China Artemisia annua traditionally has been harvested from wild natural self seeded stands. Although no specific crop production statistics are available, because of a confidentiality policy of Chinese authorities, it is believed that the bulk of Chinese production still comes from wild stands. These stands are the source of much of the artemisinin derived drugs used in China and probably the bulk of those drugs exported elsewhere (WHO, 1994) although some selected lines of Artemisia annua are cultivated as a row crop in Szechwan Province (). Ideally the harvesting of raw material for medicinal drug production from wild stands is not a good policy (). The plant material in wild stands is typically very variable in its content of the required medicinal constituents and this has an impact on the economics of drug extraction. Added to this the continual encroachment and elimination of wild stands will ultimately limit the source of genetic variability which is vital to the development of improved seed lines (). Another negative factor against utilisation of wild stands is that transport distances often become uneconomic with a crop such as Artemisia annua with a relatively low artemisinin Read more […]

Pharmacology of Poppy Alkaloids: Minor Opium Alkaloids

The pharmacology and biology of minor opium alkaloids have been surveyed previously in two comprehensive reviews (). Thebaine The pharmacology of thebaine was summarized by Reynolds and Randall in 1957 and studied comprehensively by a WHO Advisory Group in 1980. The pharmacological actions of thebaine in various isolated organs have been studied. Thebaine can induce a temporary decrease in blood pressure in anaesthetized dogs and this depressor effect showed a marked tachyphylaxis. In isolated guinea pig atrium, thebaine decreased the heart rate and contractions depending on the concentration. In isolated rabbit ileum it decreased the peristaltic movement and contractions (). The predominant effect of thebaine is stimulation of the central nervous system. In the mouse, rabbit, cat and dog increases in motor activity and reflex excitability were observed at doses around 2-10mg/kg s.c. or i.m. The Straub-tail response was noted only occasionally. The effects of thebaine on body temperature and respiration have also been studied. Convulsions were observed in almost all species of animals including the frog, pigeon, mouse, guinea pig, cat and dog. Transient tremors, restlessness and convulsions were observed in the Read more […]

Healing Powers of Aloes: Pharmacology and Therapeutic Applications

Constipation Aloe latex possesses laxative properties and has been used traditionally to treat constipation. The old practice of using aloe as a laxative drug is based on its content of anthraquinones like barbaloin, which is metabolised to the laxative aloe-emodin, isobarbaloin and chrysophanic acid. The term ‘aloe’ (or ‘aloin’) refers to a crystalline, concentrated form of the dried aloe latex. In addition, aloe latex contains large amounts of a resinous material. Following oral administration the stomach is quickly reached and the time required for passage into the intestine is determined by stomach content and gastric emptying rate. Glycosides are probably chemically stable in the stomach (pH 1–3) and the sugar moiety prevents their absorption into the upper part of the gastrointestinal tract and subsequent detoxification in the liver, which protects them from breakdown in the intestine before they reach their site of action in the colon and rectum. Once they have reached the large intestine the glycosides behave like pro-drugs, liberating the aglycones (aloe-emodin, rhein-emodin, chyrosophanol, etc.) that act as the laxatives. The metabolism takes place in the colon, where bacterial glycosidases are Read more […]

Mentha Species (Mints)

The Mentha comprise a genus of the Labiatae (Lamiaceae) that are widely distributed in the north and south temperate zones of Eurasia and Africa, and members of which have been extensively introduced into the Americas. Up to some 25 species have been characterised, but the genus is extremely complex taxonomically and much phenotypic plasticity and genetic variability occurs. Diversity in Europe appears to be at the species level whereas that in central Asia mainly involves variation within one species, i.e. M. sylvestris (). Most of the species can hybridise to yield numerous varieties that are widespread in nature and can be recognised by their intermediate appearance and general sterility – although fertile hybrid swarms are known. Consequently, the ancestry of several “species” and varieties is uncertain – especially so as several have been widely cultivated as culinary herbs and many cultivars have escaped into the environment. This variation may be responsible for differences in secondary metabolism that have often been recorded in nominally the same species. Thus it is essential that fully documented voucher specimens be deposited in herbaria when studies are carried out on the genus. Table Classification Read more […]

Mediterranean and the Near East

Alexandra senna Senna alexandrina and Tinnevelly senna S. angustifolia / Fabaceae Both species are of desert origin: Tinnevelly senna, Senna angustifolia, is native to Arabia, West Africa and Asia, as far as Punjab, while Alexandra senna, S. alexandrina, grows naturally in northeastern Africa and it is harvested and cultivated in Sudan, China, and India. About 1,000 years ago the Arabs introduced the use of dried leaves and especially fruits of senna into Western pharmacopoeias as a laxative. Senna was mentioned in detail by Ibn al-Baytar (1197-1248), one of the most important Arabian scholars of the Middle Ages and the author of the famous medical treatise Jami’ al-mufradat. Over the centuries senna has proved its worth as an herbal drug and today represents one of the most widely used herbal drugs in the classical pharmacy. Artichoke Cynara cardunculus / Asteraceae Formerly known as Cynara scolymus, the artichoke is the best example of a food-medicine in the whole of European phytotherapy. Artichokes originated in the Mediterranean region and numerous diverse cultivars were subsequently developed. Many Mediterraneans used artichokes by soaking them in wine, then drinking the liquid as a digestive and a reconstituent Read more […]

Honey: Chemical Components. Actions

Historical Note Honey has been used since ancient times as a healing agent for wounds and a treatment for gastric complaints. In ancient Greece, Hippocrates recommended honey and vinegar for pain and honey combinations for fever. It is also recommended by the Bible and Koran as a medicinal agent. Over the past few decades, scientific research has confirmed its role as a successful wound treatment. It is also known as honig and miel blanc. Chemical Components Caffeic acids, benzoic acid and its esters, phenolic acid and its esters, flavanoids, beeswax, inhibin, glucose oxidase and catalase, although other as yet unidentified constituents also exist. The composition of a particular honey greatly depends on the composition of the nectar it originated from, and therefore the plant species involved in its production. Main Actions ANTIBACTERIAL The type of plant species involved in honey production is significant, as some confer greater antibacterial properties than others. Currently, evidence suggests honey produced from the tea trees Leptospermum scoparium (New Zealand manuka) and Lipolygalifolium (Australian jelly bush) are the most effective, but batch testing is still required to verify the antibacterial activity Read more […]