Inhibition of the gastric H(+),K(+)/​ATPase by plectrinone A, a diterpenoid
isolated from Plectranthusbarbatus Andrews.

Schultz C, Bossolani MP, Torres LM, Lima/​Landman MT, Lapa AJ, Souccar C.

Universidade Federal de Sao Paulo, Escola Paulista de Medicina, Department of
Pharmacology, Natural Products Section, 04044/​020 Rua Tres de Maio 100, Sao
Paulo, SP, Brazil.

This work assessed the mechanism underlying the antisecretory gastric acid
effect of Plectranthus barbatus Andrews (Lamiaceae) and active constituents.
Popularly known as "false/​boldo", this plant is used in Brazilian folk medicine
to treat gastrointestinal and hepatic ailments. The plant aqueous extract (AE)
and isolated compounds were assayed in vivo in pylorus/​ligated mice, and in
vitro on acid secretion measured as [(14)C]/​aminopyrine ([(14)C]/​AP)
accumulation in rabbit gastric glands and gastric H(+),K(+)/​ATPase preparations.
Injected into the duodenal lumen, the AE of the plant leaves (0.5 and 1.0g/kg)
decreased the volume (62 and 76%) and total acidity (23 and 50%) of gastric acid
secretion in pylorus/​ligated mice. Bioguided purification of the AE yielded an
active fraction (IC(50)=24mug/ml) that inhibited acid secretion in rabbit
gastric glands with a potency 10 to 18 times greater than that of the
originating extract, on both the basal and stimulated acid secretion by
histamine (His) (1muM) or bethanechol (100muM). At the same concentrations the
gastric H(+),K(+)/​ATPase activity was also inhibited. The active constituent was
chemically identified as the abietanoid dienedione plectrinone A which reduced
the H(+),K(+)/​ATPase activity with IC(50)=171muM. The results indicate that
inhibition of the gastric proton pump by this diterpenoid may account for the
antisecretory acid effect and reputed antiulcer activity of Plectranthus
barbatus.

PMID: 17166678 [PubMed /​ as supplied by publisher]

2: BMC Complement Altern Med. 2006 Mar 30;6:11.

Screening of Tanzanian medicinal plants for anti/​Candida activity.

Runyoro DK, Matee MI, Ngassapa OD, Joseph CC, Mbwambo ZH.

Department of Pharmacognosy, School of Pharmacy, Muhimbili University College of
Health Sciences P,O Box 65013, Dar Es Salaam, Tanzania.

BACKGROUND: Candida albicans has become resistant to the already limited, toxic
and expensive anti/​Candida agents available in the market. These factors
necessitate the search for new anti/​fungal agents. METHODS: Sixty/​three plant
extracts, from 56 Tanzanian plant species obtained through the literature and
interviews with traditional healers, were evaluated for anti/​Candida activity.
Aqueous methanolic extracts were screened for anti/​Candida activity by
bioautography agar overlay method, using a standard strain of Candida albicans
(ATCC 90028). RESULTS: Twenty/​ seven (48%) out of the 56 plants were found to be
active. Extracts of the root barks of Albizia anthelmintica and Balanites
aegyptiaca, and roots of Plectranthus barbatus showed strong activity.
CONCLUSION: The extracts that showed strong anti/​Candida activity are worth of
further investigation in order to isolate and identify the active compounds.

Publication Types:
Research Support, Non/​U.S. Gov't

PMID: 16571139 [PubMed /​ indexed for MEDLINE]

3: J Ethnopharmacol. 2006 Jan 3;103(1):1/​24. Epub 2005 Nov 9.

Plectranthus: a review of ethnobotanical uses.

Lukhoba CW, Simmonds MS, Paton AJ.

University of Nairobi, Department of Botany, Kenya.

Plectranthus is a large and widespread genus with a diversity of ethnobotanical
uses. The genus is plagued with numerous nomenclatural disharmonies that make it
difficult to collate accurate data on the uses. The aim of this review is to
gather together all ethnobotanical information on Plectranthus and to map the
data onto the most up/​to/​date phylogenetic classification in order to see if
there are similar uses among related species and hence provide a framework for
the prediction and exploration of new uses of species. The uses of 62 species of
Plectranthus were mapped onto a current phylogeny based on DNA sequence data.
The phylogeny reveals two major Clades, 1 and 2. The members of Clade 1
(corresponding to the formally recognized genus Coleus) were richer in number
and diversity of uses than members of Clade 2 (comprising the remaining species
of Plectranthus). The high incidence of synonymy can lead to problems in
uncovering a species' ethnobotanical profile. About 30% of all citations of
Plectranthus use a synonym and most of the synonyms are attributed to 10 of the
most used species, 9 of which are in Clade 1. Members of the 'Coleus' Clade are
the most studied group both taxonomically and economically. The higher incidence
of study may be as a result of the higher diversity of uses and the fact that
species in Clade 1, such as Plectranthus barbatus, Plectranthus amboinicus and
Plectranthus mollis, are geographically more widespread than those in Clade 2.
Plectranthus species in Clade 1 are frequently used as medicines and are used to
treat a range of ailments, particularly digestive, skin, infective and
respiratory problems. Plectranthus used as foods, flavours, fodder and materials
are also mostly found in Clade 1. Monoterpenoids, sesquiterpenoids, diterpenoids
and phenolics have been reported in species of Plectranthus. The abietane
diterpenoids are the most diverse of the diterpenoids isolated from species of
Plectranthus. The labdane diterpenoid, forskolin, occurs in Plectranthus
barbatus and could explain some of the traditional uses of this species. This
review highlights the fact that not enough is known about the chemistry of other
species of Plectranthus to explain their traditional uses.

Publication Types:
Review

PMID: 16289602 [PubMed /​ indexed for MEDLINE]

4: Planta Med. 2003 Dec;69(12):1080/​5.

Antispasmodic effect of the essential oil of Plectranthus barbatus and some
major constituents on the guinea/​pig ileum.

Camara CC, Nascimento NR, Macedo/​Filho CL, Almeida FB, Fonteles MC.

Escola Superior de Agricultura de Mossoro, Departamento de Veterinaria, Mossoro,
Rio Grande do Norte, Brasil.

The effects of the Plectranthus barbatus essential oil (PBEO) at concentrations
ranging form 1 to 300 microg/mL and some major constituents, i. e.,
alpha/​pinene, myrcene and caryophyllene in the ratio and amount found in the
oil, were studied on the contractility of the guinea/​pig ileum. PBEO decreased
the basal tonus of the ileum with a maximal response (R (max); % of K
(+)/​contraction) of 62.7 +//​ 3.8 % compared with 36.6 +//​ 4.5 % inhibition
achieved with alpha/​pinene and 68 +//​ 2.6 % with papaverine. The other
constituents had only a slight effect. PBEO also blocked the phasic contractions
evoked by acetylcholine with an R (max) of 85 +//​ 3.6 % compared with 54.4 +//​
3.5 % inhibition induced by alpha/​pinene and 12.4 +//​ 5.6 % with caryophyllene.
The contractions induced by histamine or barium chloride were also decreased in
amplitude by PBEO with an R (max) of 94.3 +//​ 5.7 % and 100 %, respectively. In
addition, PBEO relaxed tissues pre/​contracted with 60 mM K (+) with an R (max)
of 89.7 +//​ 2.7 % compared with 55.4 +//​ 4.6 % relaxation induced by
alpha/​pinene. The other major constituents studied had no significant effect.
Furthermore, at the higher concentration used, i. e., 300 microg/mL, PBEO
decreased the maximal response of calcium chloride (10 ( /​ 7) to 10 ( /​ 3) M)
induced contraction in depolarized tissues by 29.1 +//​ 9.53 % (p < 0.05). In
addition, the component of the contraction elicited by a single dose of
carbachol (CCh; 100 microM) added on nifedipine (10 microM) treated tissues or
at very low extracellular calcium concentration were blocked by PBEO (300
microg/mL) in 85.7 +//​ 7.8 % (p < 0.05; n = 5) and 81.2 +//​ 6.4 % (p < 0.05; n =
4), respectively. These data show that PBEO has intestinal relaxant and
antispasmodic activity and suggest that this effect is not related to antagonism
in extracellular receptors for neurotransmitters or autacoids and it seems to
occur downstream of calcium entry or release from internal stores. The main
active principle for its relaxant and spasmolytic activity seems to be
alpha/​pinene.

PMID: 14750021 [PubMed /​ indexed for MEDLINE]

5: J Ethnopharmacol. 2003 Jul;87(1):35/​41.

Antibacterial and anti/​inflammatory activities of some plants used for medicinal
purposes in Kenya.

Matu EN, van Staden J.

Research Centre for Plant Growth and Development, School of Botany and Zoology,
University of Natal Pietermaritzburg, Private Bag X01, Scottsville 3209, South
Africa.

Aqueous, hexane and methanol extracts of 12 plant species, traditionally used in
Kenya for treatment of ailments of infectious and/or inflammatory nature were
screened for in vitro antibacterial and anti/​inflammatory activities.
Antibacterial activity was tested using the agar diffusion method while
anti/​inflammatory activity was tested using the cyclooxygenase (COX/​1) assay.
All the antibacterial activity was against Gram/​positive bacteria with nine
plant species showing some activity against Staphylococcus aureus. The highest
activity was found in the methanol extracts of Maytenus senegalensis,
Plectranthus barbatus, Zanthoxylum chalybeum, Zanthoxylum usambarense and hexane
extracts of Spiranthes mauritianum. All the plant species showed some
anti/​inflammatory activities. In most cases, methanol extracts caused higher
inhibition than aqueous and hexane extracts.

Publication Types:
Research Support, Non/​U.S. Gov't

PMID: 12787952 [PubMed /​ indexed for MEDLINE]

6: East Afr Med J. 1977 Oct;54(10):571/​3.

Perianal dermatitis in Kenya due to Plectranthus barbatus leaves (Maigoya
leaves).

Owili DM.

PMID: 608428 [PubMed /​ indexed for MEDLINE]