# Cytotoxic Effects of Citrus Peels on Breast Tumor: Opportunities for Waste to Raw Material Conversion

## TL;DR

This study explores how citrus peels, usually discarded as waste, can be used as a source of cancer-fighting compounds, focusing on their potential in breast cancer treatment.

## Contribution

The study identifies specific bioactive compounds in citrus peels from Türkiye that exhibit cytotoxic effects against breast cancer cells.

## Key findings

- Peel extracts from four citrus species showed cytotoxic activity against MCF-7 breast cancer cells.
- Compounds like isomeranzin, 3-methoxy nobiletin, nobiletin, and tangeretin were isolated and linked to anticancer effects.
- Polymethoxy flavonoids (PMFs) in citrus peels show promise as natural anticancer agents and sustainable raw materials.

## Abstract

Citrus species have long
been known
for their rich nutritional value. Recent research has shed light on
their therapeutic potential, particularly in cancer treatment. Citrus peels, on the other hand, often discarded
as waste, contain a wealth of bioactive compounds, such as flavonoids,
coumarins, and essential oil components, which have proven medicinal
properties. Converting Citrus peels
from waste products to medicinal raw materials is a crucial approach
in both healthcare and sustainability. Therefore, the present study
aims to investigate the cytotoxic potential of the peels of Citrus aurantium L., Citrus maxima (Burm.) Merr. (syn. Citrus grandis), Citrus medica L. and Citrus paradisi Macfad. cultivated in Türkiye,
and to find out the compounds responsible for the cytotoxic activity.
The cytotoxic effects of the peel extracts were evaluated on MCF-7
cell lines according to bioactivity-guided fractionation and isolation
assay procedures. The compounds CAS-5 (isomeranzin), CAS-10 (3-methoxy nobiletin), CAS-11 (nobiletin),
and CAS-12 (tangeretin) were isolated. In silico analyses conducted on the isolated compounds provided supporting
information for the results obtained from in vitro experiments regarding their anticancer activity. Indeed, one of
the key components of Citrus fruits
is polymethoxy flavonoids (PMFs), a group of bioactive constituents
recognized for their anti-inflammatory, antioxidant, and anticancer
activities. As a valuable byproduct of Citrus waste, PMFs offer a dual benefit by reducing waste while providing
a natural source of bioactive compounds and making them an exciting
research area in cancer management. The therapeutic promise of PMFs
lies not only in their ability to combat cancer but also in their
potential to contribute to sustainable practices.