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(a) (b) (c)
Figure 1. (a) Normal cells MDBK; (b) infected cells with SuHV-1; (c) infected cells with BoHV-1; (×200).
The appearance of normal cells MDBK is as shown in
Figure 1a. Figure 1b and c shows the cytopathic effect of
suid and bovine herpesviruses type 1, respectively. It is
characterized by cell rounding and ballooning. The
cytotoxic and antiviral activities of these plant extracts
against BoHV-1 and SuHV-1 are as shown in Table 2.
Most of them showed low cytotoxicity to cells with MNCC
ranging from 1.000 to 125 µg/ml, but some of them were
more cytotoxic with MNCC between 62.5 and 7.8 µg/ml.
The extracts of Bumelia sertorum, C. arabica, Endopleura
uchi, Leandra purpurescens, Psidium cattleianum and
Uncaria tomentosa presented VII greater or equal to 1.5
for both viruses. The extracts of Prunus myrtifolia and
Symphyopappus compressus were positive for BoHV-1,
while the extracts of Bauhinia blakeana, Origanum
vulgare, R. communis and Tibouchina mutabilis were
positive for SuHV-1.
DISCUSSION
Although, the collect of the plants was based on random
study of natural flora of the region/country; majority of the
plants after identification were found to be medicinal and
some of them are also part of human feeding (Cordeiro et
al., 2002). Considering the plants with antiviral effect for
at least one of the viruses, all of them have use in
Brazilian folk medicine except S. compressus. There is
no information about it in literature. These data
corroborated the importance of ethnopharmacology as an
efficient strategy for selecting a plant for drug
development and antiviral studies (Vlietinck and Vanden
Berghe, 1991; Rates, 2001; Jassim and Naji, 2003; Cos
et al., 2006).
Plant extracts should be firstly assayed for toxicity
evaluation since the safety of a therapeutic agent is of
paramount importance (Harbell et al., 1997; Rates, 2001;
Veiga et al., 2005). Cytotoxicity tests based on the cell
Fernandes et al. 2263
morphological alterations, although qualitative and more
subjective can initially be used in in vitro antiviral
screening programs when evaluating many plants.
Furthermore, with the use of the extracts in their
respective MNCC in the antiviral tests can distinguish the
antiviral effects of the possible toxic effects of the
extracts.
Studies with some of these extracts have already
demonstrated their antiviral activity as E. uchi
(Plantamed, 2009). Simões et al. (1999) reported the
antiviral effect of P. cattleianum against herpes simplex
(HSV) type 1 and 2, but using hydroalcoholic extracts
from leaves. Our extract is aqueous and then probably
the active compound could probably be a polar chemical
substance since both preparations presented activity.
Barks and roots of U. tomentosa have a broad
therapeutic potential including treatment of viral infections
(Aquino et al., 1989; Willians, 2001). Otherwise, among
the diverse properties and uses of C. arabica, L.
purpurescens and P. cattleianum, an antibacterial activity
is also included (Almeida et al., 2006; Coelho de Souza
et al., 2004; Plantamed, 2009). However, in the studies of
Mccutcheon et al. (1995), P. myrtifolia did not present
antiviral activity against other viruses including HSV type
1. Kudi and Myint (1999) showed the antiviral activity of
B. blakeana against other viruses as equine herpesvirus;
the essential oils from O, vulgare presented antibacterial
and antifungicidal activities among others (Bozin et al.,
2006). Semple et al. (1998) and Kudi and Myint (1999)
described the antiviral activities of Pittosporum undulatum
and Cassia ferruginea, respectively, against a range of
viruses, although these plants were not active in this
study for the two herpesviruses.
Researches for antiviral effects of plant extracts against
these two herpesviruses have continuously been made
(Ahmad et al., 1996; Simoni et al., 1996; Summerfield et
al., 1997; Barrio and Parra, 2000; Felipe et al., 2006;
Simoni et al., 2007). The positive plants for the BoHV-1