White mulberry (Morus alba) – between traditional use and analytical characterisation

The leaves of the white mulberry (Morus alba) have been used in traditional Chinese medicine (TCM) for a long time now. They also play an important role in the silk production process, as they are regarded as being an essential source of food for silkworm caterpillars (Bombyx mori). In recent years, the plant has attracted extra attention in the context of modern research – particularly with regard to the regulation of blood sugar levels and metabolic health.

This scientific interest and the latest research findings on its metabolic effects have led to intensified use of white mulberry as a functional food or dietary supplement and, with it, a growing awareness of the importance of precise analytical characterisation. Laboratories, manufacturers, and quality managers are now faced with a pivotal question:

How can the complex phytochemical profile of Morus alba be captured in a valid and reproducible manner?

Traditional use as a starting point for modern research

Morus alba originates from East Asia and is now cultivated worldwide. Silkworms feed almost exclusively on mulberry leaves and show a preference for the leaves of the white mulberry tree.

In traditional Chinese medicine (TCM), the leaves are predominantly used to treat respiratory or metabolic complaints. In TCM, they are known as Sang Yè and are primarily associated with the lung and liver meridians.

Modern research is concentrating on potential mechanisms involved in carbohydrate metabolism to an increasing extent. This is shifting the focus away from traditional applications in the direction of experimental investigations of constituent substances and analytically resilient profiles.

Why Morus alba is currently in focus

One of the reasons for the scientific interest in white mulberry can be found in the bioactive substances that it contains, which particularly include the piperidine alkaloid 1-Deoxynojirimycin (1-DNJ). In experimental studies, 1-DNJ has been found to exert an inhibitory effect on α-glucosidases, which are enzymes involved in breaking down complex carbohydrates. This retards the breakdown of carbohydrates in the intestine, resulting in a more even increase in blood sugar levels.

Morus alba also contains numerous other relevant phytochemicals, such as

• flavonoids: morin, mulberrin, rutin, quercetin-3-glucoside
• phenylpropanoids: morusin, trans-Oxyresveratrol, mulberroside A

These compounds are associated with antioxidant, anti-inflammatory, or neuroprotective properties in the reference literature. As far as an assessment of quality is concerned, this means:

The complete phytochemical profile is decisive for the characterisation of Morus alba raw materials, not its individual constituents.

Complex plant matrices pose analytical challenges

The composition of Morus alba extracts varies according to origin, harvesting time, processing and extraction method. The spectrum of constituent substance classes poses special challenges for suitable analytical procedures.

Chromatographic methods, such as HPLC or LC-MS, are therefore often used for characterisation, in order to map both individual substances and the complete profile. Important aspects include the following:

• Unambiguous identification of relevant compounds
• Quantitative determination of selected components

Evidence and regulatory aspects

Although preclinical studies give interesting insights, the data available for human applications is still limited. While many studies have been carried out on the basis of in vitro experiments or animal models, clinical data is less comprehensive.

In the context of long-term safety, the majority of studies performed so far have also been conducted over shorter periods of use. As far as dietary supplements, functional food, or traditional herbal medicines are concerned, this means that:

The assessment is currently based on a limited but growing body of evidence, without fully harmonized regulatory classification.

This being the case, transparent product characterisation and analytical validation is becoming increasingly important along the entire length of the value creation chain.

Conclusion

While Morus alba is entrenched in tradition and the subject of an increasing number of scientific studies, its regulatory classification continues to be dynamic.

The plant’s complex substance profile exemplifies the challenges that botanical raw materials pose for chemical analysis, standardisation and quality control. A comprehensive analytical characterisation is crucial in order to bring scientific findings, product specifications and regulatory requirements together in the long term.