Antioxidant Activity, Polyphenolic Content, and FT-NIR Analysis of Different Aspilia africana Medicinal Plant Tissues

Abstract

Aspilia africana has been used for generations to treat many diseases in Africa. Its biological activities, including antioxidant and anti-inflammatory potential, are attributed to a number of secondary metabolites, including alkaloids and polyphenolics. The antioxidant activities of A. africana callus (CA), juvenile in vitro leaf (IL) and root (IR), ex vitro root (SR) and leaf (SL), and wild leaf (WL) dried samples were assessed based on their diphenylpicrylhydrazyl (DPPH) free radical scavenging abilities. The total phenolic and flavonoid content of different plant samples was compared. Further, high-pressure liquid chromatography (HPLC) was used to quantitatively determine chlorogenic acid content in the A. africana plant samples. Fourier transform near-infrared (FT-NIR) analysis was also carried out to compare the antioxidant phytochemical content in the A. africana plant tissues. Among the samples, IR, with the highest total phenolic content (167.84 ± 1.057 mg GAE/g), total flavonoid content (135.06 ± 0.786 mg RUE/g), and chlorogenic acid (5.23 ± 0.298 mg/g) content, had the most potent antioxidant activity (IC50 = 27.25 ± 5.028 μg/mL), followed by WL. The lowest polyphenolic content and antioxidant activity were observed in SR. The antioxidant activities of A. africana tissues were positively correlated with the total phenolic and flavonoid content in the samples. The differences in antioxidant activities of A. africana tissues could be attributed to the difference in their polyphenolic content. Our study reports, for the first time, the antioxidant activities of A. africana callus and roots (in vitro and ex vitro). The A. africana samples IR, CA, and WL could be valuable natural sources of antioxidants that could be further exploited for the development of useful pharmaceutical products.

Indirect in vitro Regeneration of the Medicinal Plant, Aspilia africana, and Histological Assessment at Different Developmental Stages

“…The biological activities of medicinal plants, such as antioxidant, antimicrobial, and anti-inflammatory activities, largely depend on these phytochemicals. We found that the in vitro regenerated tissues had high antioxidant activity (Okello et al, 2021a). These in vitro regenerated plant tissues could be a valuable natural source of antioxidants and could be further exploited for the development of useful pharmaceutical products (Okello et al, 2021a).…”

“…We found that the in vitro regenerated tissues had high antioxidant activity (Okello et al, 2021a). These in vitro regenerated plant tissues could be a valuable natural source of antioxidants and could be further exploited for the development of useful pharmaceutical products (Okello et al, 2021a).…”

“…Interestingly, a study of the total phenolic, flavonoid, and chlorogenic acid contents of the in vitro regenerated callus and juvenile plant tissues showed high quantities of these pharmacologically important phytochemicals (Okello et al, 2021a). The biological activities of medicinal plants, such as antioxidant, antimicrobial, and anti-inflammatory activities, largely depend on these phytochemicals.…”

“…The leaf tissues of the micropropagated plants differentiated fully during acclimatization (Shekhawat and Manokari, 2018;Okello et al, 2021c). The in vitro regenerated tissues were shown to contain high total flavonoids, phenolics, and chlorogenic acids; had good antioxidant potential; and could be used as a sustainable source of raw materials in the development of important pharmaceutical products (Okello et al, 2021a). Our study presents an efficient reproducible protocol for the indirect regeneration of A. africana, which offers a basis for its large-scale multiplication, domestication, and germplasm preservation.…”

“…Due to the economic and medicinal values of the plant, developing a micropropagation protocol for A. africana would greatly offset pressures on the natural populations, thus making a vital contribution to its conservation. With the proven biological efficacy of the in vitro regenerated A. africana tissues such as the callus and juvenile roots (Okello et al, 2021a), these in vitro regenerated tissues could offer an alternative sustainable source of raw materials to the pharmaceutical industry. Furthermore, in this study, we performed a histological assessment of the tissues during different stages of development from callus through shoot organogenesis to fully developed plantlets.…”