# Piper nigrum Extract as an Adjuvant in a Collagen System for Infected Wound Healing: Therapeutic Synergy and Biocompatibility

## TL;DR

This study shows that adding black pepper extract to a collagen system improves wound healing by boosting antibiotic effectiveness and offering antioxidant and antibacterial benefits.

## Contribution

The novel contribution is the development of a collagen-based composite with P. nigrum extract that synergizes with cefazolin for infected wound healing.

## Key findings

- Piper nigrum extract contains polyphenols with strong antioxidant and antibacterial properties.
- The collagen composite with the extract showed synergy with cefazolin against microbial strains.
- The material demonstrated biocompatibility and hemocompatibility in cell tests.

## Abstract

Background/Objectives: Natural plant-based compounds, especially black pepper extract, are known to have anti-inflammatory, antibacterial, and antioxidant qualities that promote procollagen formation and wound healing. This study focused on developing a collagen-based composite enriched with P. nigrum extract in powder form, designed to enhance the efficacy of the antibiotic cefazolin while promoting the healing of chronic wounds. Methods: The polyphenolic P. nigrum extract was obtained by ultrasound-assisted extraction and was characterised by UHPLC-MS/MS and spectrophotometry. Antimicrobial and antioxidant activities were assessed using conventional methods. Pharmacokinetic and pharmacodynamic parameters were evaluated for the specific taxon compounds using Deep-RK. P. nigrum extract was incorporated into a collagen hydrogel with arginine and freeze-dried. The powders were characterised by FTIR, SEM, TGA-DSC, and DLS. The antimicrobial activity and potential synergistic effects with cefazolin were evaluated on reference microbial strains and isolates from infected wounds. Biocompatibility and hemocompatibility were evaluated, as well as wound closure in vitro. Results: Polyphenols, including phenolic acids, stilbenes, anthocyanins, and flavonoids, which provide a potent antioxidant capacity through electron transfer mechanisms (FRAP, CUPRAC), were abundant in the P. nigrum extract. FTIR and SEM analyses confirmed the integration of phenolic compounds into the collagen–arginine matrix without protein denaturation. TGA–DSC data showed thermal stabilisation at moderate extract concentrations. The extract exhibited predominantly bacteriostatic antibacterial activity and antibiofilm effects, with synergy/additivity with cefazolin, especially at medium doses. Tests on keratinocytes confirmed biocompatibility, and hemocompatibility demonstrated an excellent safety profile, with protection against AAPH-induced oxidative stress. Conclusions: Overall, collagen powders with P. nigrum extract at moderate/low concentrations combine stability, antibiotic-enhanced activity, and cellular compatibility, making them promising adjuvants for the topical treatment of chronically infected wounds.