The aim of this study was to investigate the properties of di-rhamnolipid [α-L-rhamnopyranosyl-(1-2)-α-L-rhamnopyranosyl-3-hydroxydecanoyl-3-hydroxydecanoic acid, also referred to as dirhamnolipid BAC-3] relating to the process of cutaneous wound healing. Di-rhamnolipid was prepared in a eucerin ointment and applied topically on full-thickness burn wounds in normal Sprague-Dawley rats covering 5% of the total body surface area. The rate of wound closure was measured over the period of 45 days. The collagen content was evaluated microscopically, by performing densitometric analysis on Verhoeff's stained histopathological slides of wound biopsies taken at the end of 45th day of di-rhamnolipid treatment. Di-rhamnolipid toxicity was assessed with the subcutaneous multi-dose study in Swiss-Webster mice. The treatment of full-thickness-burn wounds with topical 0.1% di-rhamnolipid accelerated the closure of wounds on day 21 of the treatment by 32% compared to the control ( p < 0.05). On day 35, the wounds closed in all animalstreated with 0.1% di-rhamnolipid ointment while some rats in the control group had open wounds on days 35 and even 45. Histologic comparisons have shown that di-rhamnolipid significantly decreased collagen content in burn wounds (47.5%, p < 0.05) as compared to the vehicle-treated (control) wounds. Di-rhamnolipid was well-tolerated. The results of this study raise the possibility of potential efficacy of di-rhamnolipid in accelerating normal wound healing and perhaps in overcoming defects associated with healing failure in chronic wounds.

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In this study, we discovered that flavonoids belonging to the subclasses: (flavanone, flavone, and flavonol) display differential effects on the synthesis of collagen in human dermal fibroblasts. At 80 microg/ml flavonoids quercetin-3,3',4', 5,7-pentahydroxyflavone, 3-methyl quercetin, and 7-hydroxyflavone significantly decreased the total protein concentration which was a direct consequence of their cytotoxic effect, while naringenin exhibited no effect on total collagen and total protein concentration. Quercetin-3,3'4',7-tetramethyl ether, 4'-hydroxyflavanone, flavanone, and fisetin significantly decreased collagen concentration while morin, rutin, and chrysin increased collagen concentration without changing the overall protein concentration. The initial screening performed in this study enables the identification of compounds that exert significant effects on fibroblast function and show potential as starting material for pharmaceutical preparations targeted against various disorders centered around disturbed collagen metabolism.

This case demonstrates that application of dirhamnolipid resulted in the healing of a chronic decubitus ulcer in an elderly, debilitated patient and might be a useful therapy to improve healing of decubitus ulcers.