371
The potential role of Aloe species’ with respect to bioactivity, availability and
safety makes it an interesting alternative as control agent especially used in preharvest and postharvest fungal diseases of vegetables and fruits. Ali et al. (1999)
reported that fresh leaves extracts of A. arborescens and A. barbadensis have antifungal potential against Fusarium moniliforme, Aspergillus niger and Cladosporium
herbarum. Research studies have shown that up to 20% of Alternaria, Penicillium
and Botrytis spores survival was reduced by A. vera and it also inhibits up to 38%
of Colleotrichum, Fusarium and Rhizoctonia mycelium growth (De Rodrýguez
et al. 2005; Castillo et al. 2010).
Ortega-Toro (2017) analyzed anti-fungal potential of A. vera gel against six
fungi causing plant diseases- Botryotinia fuckeliana, Fusarium oxysporum,
Colletotrichum gloeosporioides, Curvularia hawaiiensis, Alternaria alternate and
Bipolaris spicifera. Results showed that was most effective against F. oxysporum.
RP-HPLC fractionated methanolic extracts of inner leaf gel of A. barbadensis were
tested against nystatin resistant strain of the fungus Aspergillus niger and it was
found that A. barbadensis was capable of inhibiting the growth of this resistant
strain (Cock 2007). Research studies shows that fungal contamination were effectively controlled with highest A. vera ratio, treatment of A. vera gel with nectarine
alone or with thymol addition inhibits fungal growth of Penicillium digitatum,
Rhizopus stolonifer and Botrytis cinerea. Hence, application of Aloe significantly
lowers two to threefold fungal infection than in non-treated nectarines. It was
noticed that efficiency of Aloe gel to reduce infection was not improved by addition
of thymol (Navarro et al. 2011).
Eight Aloe species gels (A. vera L., A. arborescens Mill., A. claviflora
Strydenburg., A. mitriformis Mill., A. aristata Haw., A. ferox Mill., A. striata Haw.
and A. saponaria A.) were evaluated for anti-fungal activity against P. italicum,
P. italicum, P. expansum and P. digitatum. Results concluded that higher antifungal
activity was observed for A. saponaria, A. ferox and A. mitriformis than A. vera
which can be correlated with aloin content (Zapata et al. 2013).
18.7 Toxicological Profiling
It was observed that aloe vera gel or extract usually does not possess any toxicity
although different cases of people are found having sensitivity towards them and
suffered from liver problems. On using externally, many individuals have also experienced many skin problems like itching and swelling etc.
The adverse effects of aloe leaf and latex are:
• Oral ingestion of aloe spp. could be potentially toxic, and may cause abdominal
cramps and diarrhea .
• Ingestion of non-decolorized liquid aloe vera is a possible carcinogen, Under the
guidelines of California Proposition 65, orally ingested non-decolorized aloe
vera leaf extract has been listed by the OEHHA, along with goldenseal, among
18 Aloe Species as Valuable Sources of Functional Bioactives
The potential role of Aloe species’ with respect to bioactivity, availability and
safety makes it an interesting alternative as control agent especially used in preharvest and postharvest fungal diseases of vegetables and fruits. Ali et al. (1999)
reported that fresh leaves extracts of A. arborescens and A. barbadensis have antifungal potential against Fusarium moniliforme, Aspergillus niger and Cladosporium
herbarum. Research studies have shown that up to 20% of Alternaria, Penicillium
and Botrytis spores survival was reduced by A. vera and it also inhibits up to 38%
of Colleotrichum, Fusarium and Rhizoctonia mycelium growth (De Rodrýguez
et al. 2005; Castillo et al. 2010).
Ortega-Toro (2017) analyzed anti-fungal potential of A. vera gel against six
fungi causing plant diseases- Botryotinia fuckeliana, Fusarium oxysporum,
Colletotrichum gloeosporioides, Curvularia hawaiiensis, Alternaria alternate and
Bipolaris spicifera. Results showed that was most effective against F. oxysporum.
RP-HPLC fractionated methanolic extracts of inner leaf gel of A. barbadensis were
tested against nystatin resistant strain of the fungus Aspergillus niger and it was
found that A. barbadensis was capable of inhibiting the growth of this resistant
strain (Cock 2007). Research studies shows that fungal contamination were effectively controlled with highest A. vera ratio, treatment of A. vera gel with nectarine
alone or with thymol addition inhibits fungal growth of Penicillium digitatum,
Rhizopus stolonifer and Botrytis cinerea. Hence, application of Aloe significantly
lowers two to threefold fungal infection than in non-treated nectarines. It was
noticed that efficiency of Aloe gel to reduce infection was not improved by addition
of thymol (Navarro et al. 2011).
Eight Aloe species gels (A. vera L., A. arborescens Mill., A. claviflora
Strydenburg., A. mitriformis Mill., A. aristata Haw., A. ferox Mill., A. striata Haw.
and A. saponaria A.) were evaluated for anti-fungal activity against P. italicum,
P. italicum, P. expansum and P. digitatum. Results concluded that higher antifungal
activity was observed for A. saponaria, A. ferox and A. mitriformis than A. vera
which can be correlated with aloin content (Zapata et al. 2013).
18.7 Toxicological Profiling
It was observed that aloe vera gel or extract usually does not possess any toxicity
although different cases of people are found having sensitivity towards them and
suffered from liver problems. On using externally, many individuals have also experienced many skin problems like itching and swelling etc.
The adverse effects of aloe leaf and latex are:
• Oral ingestion of aloe spp. could be potentially toxic, and may cause abdominal
cramps and diarrhea .
• Ingestion of non-decolorized liquid aloe vera is a possible carcinogen, Under the
guidelines of California Proposition 65, orally ingested non-decolorized aloe
vera leaf extract has been listed by the OEHHA, along with goldenseal, among
18 Aloe Species as Valuable Sources of Functional Bioactives