Manley E West

The past and present use of plants for medicines

Evidence of the use of plants for medicinal purposes dates as far back as 60 000 years ago (1) in both western and eastern cultures; in both developed and undeveloped countries. For example, the pharmacopoeia of Emperor Shen Nung of China, around 2730–3000 BC, describes the medicinal use of plants such as Hemp, Aconite, Opium. The Egyptian Pharmacopoeia of Ebers Papyrus, written about 1500 BC, documents the medicinal use of plant extracts such as the poppy of Opium and oil of Castor beans (2, 3). Some of the plants commonly used today, such as peppermint (Mentha piperita), poppy (Papaver somniferum), mugwort (Artemisia vulgaris), sage (Horminum pyrenaicum), rosemary (Hyssopus officinalis), rue (Ruta graveolens) and verbena (Verbena officinalis) are well documented in the “Materia medica” of the great physician Hippocrates (about 460–370 BC) and in the several manuscripts written (around 160 AD) by Galen, a surgeon from Asia Minor. In early civilizations, illness was usually believed to be due to divine punishment. The Aztecs Indian of South America, for example, believed that particular diseases were linked to specific gods; thus their god Tlaloc was associated with diseases caused by water, such as oedema (4). Similarly, Greek physicians, such as Theoprastus, were generally followers of Asclepius, the god of Medicine. Thus the use of plants for healing became strongly associated with the gods. With the fall of the Roman Empire and the advancement of Christianity in western cultures, the use of plants for healing was discouraged. Ironically, although early Christians also saw disease and illness as divine (heaven-sent) punishment, they believed it could only be cured through repentance and prayer, not through the use of medicinal plants. Additionally, as Christianity only recognizes the power of one God, the strong association of many gods and plant medicines led to the value of plant medicines becoming clouded in myths. By the 1500s AD, the use of plants as medicine in western society became further mystified by the “Doctrine of Signatures”. Supporters of the doctrine believed that the physical attributes of plants were indications of their medicinal value. Thus, the holes in the leaves of St John’s wort (Hypericum perforatum) signified

Isolation of a muscarinic alkaloid with ocular hypotensive action from Trophis racemosa

A muscarinic alkaloid with a quaternary nitrogen was isolated from Trophis racemosa. Aqueous solutions (0.5%–2%) of the chloride salt of the alkaloid produced dose‐dependent reductions of intra‐ocular pressure ranging from 6.6 ± 0.7 mmHg to 15.7 ± 0.3 mmHg, (p < 0.001, n = 5) in dogs. Atropine (0.1 mL of a 1% solution) and pirenzepine at a non selective antagonist dose (0.1 mL of 0.5% solution) for M1 and M3 receptors blocked the reduction of intra‐ocular pressure, but alpha‐adrenoceptor blockade with phenoxybenzamine (0.1 mL of a 1% solution) did not block the reduction of intra‐ocular pressure. On the isolated guinea‐pig ileum and trachea, the alkaloid produced contractions which were inhibited by atropine (6 × 10−7M or 0.4 µg/mL) and by pirenzepine at a non‐selective antagonist dose (3.1 × 10−6M or 1.3 µg/mL) for M1 and M3 receptors. But neither selective blockade of M2 receptors with gallamine (1.7 × 10−6M or 1.5 µg/mL) nor selective blockade of M1 receptors with pirenzepine (7 × 10−9M or 3 ng/mL) inhibited the alkaloid‐induced contractions. There was also no inhibition of the alkaloid‐induced contractions in the presence of ganglionic nicotinic receptor blockade with pentolinium (5.6 × 10−7M or 0.3 µg/mL) and hexamethonium (1.7 × 10−6M or 0.6 µg/mL), but nicotine‐induced contractions were inhibited by these ganglionic blockers. These results suggest that a muscarinic alkaloid from Trophis racemosa produced ocular hypotension via M3 receptor stimulation in dogs. Copyright

An alkaloidal extract (ALKS1) from Trophis racemosa lowers intraocular pressure in dogs

A 1.0% solution of ALKS1, an alkaloidal extract obtained from Trophis racemosa, produced a significant fall in intraocular pressure in the dogs eye (p <0.001). The fall was antagonized by atropine (p <0.0025), suggesting ALKS1 is acting through a muscarinic mode of action. Further purifcation of the extract is required to determine the actual compound producing this effect on the eye.

Choline Supplementation Facilitates Short-term Memory Consolidation into Intermediate Long-term Memory of Young Sprague-Dawley Rats

Choline is important for the synthesis of acetylcholine, an integral neurotransmitter involved in memory formation. In order to investigate the effect of choline supplementation on memory consolidation, the study utilized a T-maze to facilitate passive avoidance learning and memory in young female Sprague-Dawley rats. Rats were placed in two groups; choline-supplemented that received choline chloride daily for two weeks, and control that received vehicle daily for two weeks. Rats were evaluated to determine their ability to avoid an aversive electric foot-shock (0.1 mA at 60V) when they characteristically entered the preferred dark area (DA) of the T-maze. Both groups of rats showed preference, without significant difference, for entry into DA of the T-maze. However, fifteen minutes after passive avoidance both choline supplemented and control rats avoided entry into DA. This display of DA avoidance 15 minutes after training, suggests that both groups of rats had acquired short-term memory of the aversive stimulus. However, when the test was repeated 24 hours after training, the control group did not avoid entry into DA, whereas the choline-supplemented group either avoided entry or entered after a significantly longer latency period (p < 0.01). These results suggest that supplementation with choline facilitated the consolidation of short-term memory of the avoidance learning into intermediate long-term memory in young rats.

Acute toxicity of seeds of the sapodilla (Achras sapota L.)

An aqueous extract of the sapodilla seed (Achras sapota L.) was acutely toxic to mice and rats (i.p. LD50 = 190 and 250 mg/kg, respectively) with symptoms of dyspnoea, apnoea and convulsions. Soxhlet extraction and chromatographic separation of the seed constituents yielded a brown amorphous solid containing saponin. This was heat-stable and toxic by the i.p. route (LD50 = 30-50 mg/kg) but non-toxic by the oral route in mice and rats. It is proposed that the toxicity of the sapodilla seed is due mainly to the saponin content.