Unpublished Work on Other Members of the Combretaceae
Two antibacterial flavonoids were isolated from Combretum apiculatum subsp.
apiculatum [61]. In his PhD study, Angeh isolated three antibacterial compounds,
a new oleanene-type triterpenoid glycoside and two known triterpenoids from
Combretum padoides [62]. He also isolated a new antibacterial pentacyclic triterpen-
oid and four antibacterial triterpenoids with known structures from the leaves of
Combretum imberbe [62].
Antifungal Activity
We have adapted our procedures to facilitate the investigation of antifungal activ-
ities of plant extracts. These methods were applied in the investigation of the anti-
112 5 Plant Extracts Used to Manage Bacterial, Fungal, and Parasitic Infections in Southern Africa
fungal activity of Combretum and Terminalia (another genus of the Combretaceae)
species [27]. The rising incidence of opportunistic mycotic infections associated
with AIDS, as well as those developing after treatment with immunosuppressive
drugs, has supplied impetus to the search for new antifungal drugs. There have
been several publications produced by diverse research groups on antifungal ef-
fects of South African plants [27, 53, 63, 64].
We concentrate on researching the antifungal properties of plants against fungi
implicated in causing opportunistic diseases in immunocompromised patients,
such as Candida albicans and Cryptococcus neoformans. The microplate method for
detecting antibacterial activity has been modified to result in a method appropriate
for the antifungal testing of extracts [27]. Using this method, significant antifungal
activity was found in several Terminalia species (Combretaceae) against a range of
fungal organisms [27]. The antifungal activity of acetone, hexane, dichlorome-
thane, and methanol leaf extracts of six Terminalia species (T. prunioides, T. brachystemma,
T. sericea, T. gazensis, T. mollis, and T. sambesiaca) was tested against
five fungal animal pathogens (Candida albicans, Cryptococcus neoformans, Aspergil-
lus fumigatus, Microsporum canis, and Sporothrix schenckii). Fungi cultured from
clinical cases of disease in animals were used in the screening procedure. These
fungi represent the different morphological forms of fungi, namely yeasts (Candi-
da albicans and Cryptococcus neoformans), thermally dimorphic fungi (Sporothrix
schenckii) and moulds (Aspergillus fumigatus) and are the most common and impor-
tant disease-causing fungi of animals. Methanol extracted the highest quantity, but
the acetone extracts had the highest antifungal activity. Some of the extracts had
antioxidant activity. Most of the antifungal extracts had MIC values of about
0.08 mg mL–1, some with MIC values as low as 0.02 mg mL–1. Microsporum canis
was the most susceptible microorganism and T. sericea extracts were the most ac-
tive against nearly all microorganisms tested.
Recent research being prepared for publication indicates that more than 30 spe-
cies from the family Combretaceae display antifungal MIC values of less than
20 μg mL–1 against fungal species in vitro. This work has been extended to include
an in vivo rat model, where plant extracts with good antifungal activity are applied
to fungally inoculated lesions on rat skin. The healing of the wound is compared
with nontreated infected controls, and this method is producing good results.
Currently, efforts are being directed at discovering extracts with activity against
a spectrum of plant pathogenic fungi. The aim is to develop plant extracts with the
ability to protect other plants (crops and ornamentals) from fungal attack, both be-
fore and after harvesting.
Two antibacterial flavonoids were isolated from Combretum apiculatum subsp.
apiculatum [61]. In his PhD study, Angeh isolated three antibacterial compounds,
a new oleanene-type triterpenoid glycoside and two known triterpenoids from
Combretum padoides [62]. He also isolated a new antibacterial pentacyclic triterpen-
oid and four antibacterial triterpenoids with known structures from the leaves of
Combretum imberbe [62].
Antifungal Activity
We have adapted our procedures to facilitate the investigation of antifungal activ-
ities of plant extracts. These methods were applied in the investigation of the anti-
112 5 Plant Extracts Used to Manage Bacterial, Fungal, and Parasitic Infections in Southern Africa
fungal activity of Combretum and Terminalia (another genus of the Combretaceae)
species [27]. The rising incidence of opportunistic mycotic infections associated
with AIDS, as well as those developing after treatment with immunosuppressive
drugs, has supplied impetus to the search for new antifungal drugs. There have
been several publications produced by diverse research groups on antifungal ef-
fects of South African plants [27, 53, 63, 64].
We concentrate on researching the antifungal properties of plants against fungi
implicated in causing opportunistic diseases in immunocompromised patients,
such as Candida albicans and Cryptococcus neoformans. The microplate method for
detecting antibacterial activity has been modified to result in a method appropriate
for the antifungal testing of extracts [27]. Using this method, significant antifungal
activity was found in several Terminalia species (Combretaceae) against a range of
fungal organisms [27]. The antifungal activity of acetone, hexane, dichlorome-
thane, and methanol leaf extracts of six Terminalia species (T. prunioides, T. brachystemma,
T. sericea, T. gazensis, T. mollis, and T. sambesiaca) was tested against
five fungal animal pathogens (Candida albicans, Cryptococcus neoformans, Aspergil-
lus fumigatus, Microsporum canis, and Sporothrix schenckii). Fungi cultured from
clinical cases of disease in animals were used in the screening procedure. These
fungi represent the different morphological forms of fungi, namely yeasts (Candi-
da albicans and Cryptococcus neoformans), thermally dimorphic fungi (Sporothrix
schenckii) and moulds (Aspergillus fumigatus) and are the most common and impor-
tant disease-causing fungi of animals. Methanol extracted the highest quantity, but
the acetone extracts had the highest antifungal activity. Some of the extracts had
antioxidant activity. Most of the antifungal extracts had MIC values of about
0.08 mg mL–1, some with MIC values as low as 0.02 mg mL–1. Microsporum canis
was the most susceptible microorganism and T. sericea extracts were the most ac-
tive against nearly all microorganisms tested.
Recent research being prepared for publication indicates that more than 30 spe-
cies from the family Combretaceae display antifungal MIC values of less than
20 μg mL–1 against fungal species in vitro. This work has been extended to include
an in vivo rat model, where plant extracts with good antifungal activity are applied
to fungally inoculated lesions on rat skin. The healing of the wound is compared
with nontreated infected controls, and this method is producing good results.
Currently, efforts are being directed at discovering extracts with activity against
a spectrum of plant pathogenic fungi. The aim is to develop plant extracts with the
ability to protect other plants (crops and ornamentals) from fungal attack, both be-
fore and after harvesting.
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