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Title: In vitro wound healing effects of single and combined African herbal medicines
Author: Krishnan, P. R.
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 2005
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Impaired and aberrant wound healing imposes a huge financial burden in the developed world and is an insurmountable problem in the undeveloped one. Many new approaches, such as gene therapy and tissue engineered skin have met with limited success. The application of plant-based medicines provides, in principle, a cost effective therapy; a major criticism of herbal medicines, however, is that they are not subjected to the rigours of their pharmaceutical counterparts. This work scientifically investigates the effects of four African herbal medicines used generally in the treatment of wounds; the behaviour of normal human dermal fibroblasts (NHDF) is known to be crucial to the onset of wound healing disorders and culture of this cell type was the means by which effects were gauged. The herbs are Cissus rotundifolia leaf extract (C. rotundifolia(L)), Cassia abbreviate bark extract (C. abbreviata(B)) Zanthoxylum chalybeum bark extract (z chalybeum(B)) and Zanthoxylem chalybeum leaf extract (Z chalybeumQS)).Aqueous extractions of herbal medicines were used in all experiments. Single and paired combinations of the herbal medicines were assessed. The effects of combinations were compared to a theoretical additive (obtained by the summation of individual herbal extract effects); thus, combination behaviour was defined in terms of being additive, greater than additive or less than additive The effects of single and combined herbal extracts on cultured NHDF were assessed with respect to the following wound healing parameters:1. Growth of NHDF in basal media (to unequivocally establish the extent of effects) and basal media /2%FBS (to simulate impaired healing).2. Growth of NHDF in basal media /10% FBS + 70 μg / ml of insulin-like growth factor (to simulate fíbrotic healing)3. NHDF exposed to H2O21 FeSOa oxidant environment (to simulate impaired healing). NHDF were either pre-incubated with herbal extracts for 12 һ (to assess protective effects) or exposed to oxidants and extracts simultaneously (to assess the ability of extracts to neutralise oxidants) 4. NHDF production of pro-collagen type I carboxypeptide (PICP) and keratinocyte growth factor (KGF)For growth related effects and the extent to which NHDF were damaged by exposure to oxidants, the MTS assay was used as an indirect determination of viable cell number. The production of biomolecules (PICP and KGF), was measured by enzyme linked immunosorbent assay (ELISA).С. rotmdifolia(L) and c. abbreviate(B) enhanced the growth of NHDF in basal media and basal media /2% FBS.Combinations of these herbal extracts, when applied in basal media, produced less than additive effects when the c. rotundifolia(L) proportion exceeded 1:1 but greater than additive effects at с rotundifolia(L) proportions of 1:1 or less.In the case of c. rotundifolia(L) I c. abbreviata(B) combinations applied in basalmedia / 2% FBS, the effects were greater than additive at all proportions.Ζ chalybeum(B) had antiproliferative effects on the NHDF fibrotic model. When combined with Z chalybeum{B) in proportions greater than 1:1, с rotundifoliaQS) reduced the extent to which z chalybeum(B) was able to inhibit growth; when present in proportions of 1:1 or less, c. rotundifolia(L) was not able to influence the effects of Z chalybeum(s).Neither single nor combined herbal extracts had any effect on the production of biomolecules such as PICP and KGF. The apparent changes corresponding to the application of с rotundifoliaÇL), с. abbreviata(B) and z chalybeum(B) were due entirely to their growth-related effects. In terms of antioxidant effects, none of the herbal extracts (single or combined), when incubated with NHDF prior to oxidant addition, were able to protect cells from damage. C. rotundifoliai(L), z. chalybeum(L) and z chalybeum(B), in descending order of potency, demonstrated an ability to neutralise the effects of oxidants when oxidant and herbal extracts were added simultaneously. Combinations of c. rotundifolia(L) and z chalybeum(L) produced effects which were additive at all proportions. Combinations of c. rotundifolia(L) and z chalybeum(L) produced effects which were additive at z chalybeum(L) proportions greater than 1:1 but super-additive at X. chalybeum(L) proportions of 1:1 or less. Combinations of z chalybeum(B) and z chalybeum(L) were less than additive at all proportions. The work has provided an appropriate platform for the broader study of the four herbal medicines and it is reasonable to conclude that there is a scientific basis for the application of these herbal extracts to the treatment of wounds and wound healing disorders. All of the herbal extracts have influenced at least one of the selected wound healing aspects, whether singly or in combination; in particular, c. rotundifolia(L) and Z chalybeum(L) have demonstrated growth related and antioxidant properties. The further investigation of effective herbs, in terms of other skin cell types (keratinocytes or endothelial cells) or more involved study (organ culture, human trials) would be of merit.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available