## 1 Introduction  
Arthritis, derived from the old Greek term \"diseases of the joints\", refers to inflammation with co-existed pain or structural damage. There are more than 100 types of arthritis, characterized by pain, stiffness, swelling, loss of function, weakness, deformity, and instability of joints. Both osteoarthritis and rheumatoid arthritis are common types of arthritis [1]. The affected joints can be found in the knees, hips, shoulders, and hands. Different joints are often susceptible to different arthritis. The treatment strategies also vary. General treatments for osteoarthritis include exercises, physical therapy, topical or oral medications for pain control [2], and surgical intervention for joint replacement [3]. As for rheumatoid arthritis, anti-inflammatory are used for early disease remission and preventing radiographic progression [4]. In the United States, approximately 22.7% of adults have received a diagnosis of arthritis, with 43.5% of those individuals experiencing activity limitations as a result of the condition [5]. The average medical cost for an individual with arthritis was estimated at USD 9554 annually and patients with arthritis resulted in USD 460 billion in all-cause medical costs [6]. The high prevalence of arthritis takes a toll on the economy and the patient's life quality. Therefore, exploring effective and economical ways of treatment becomes a pressing issue. Willow bark, also known as _Salix_, has been historically used for medicinal purposes for over 3500 years [7]. In the ancient world, people in Egypt, South America, Classical Greece, and China used willow bark as medicine. Sumerians and Ancient Egyptians utilized it as a painkiller and antipyretic. The therapeutic benefits of willow bark were recognized by ancient Roman and Greek physicians, including [PERSON]. In the fourth century BC, [PERSON] used willow bark to treat inflammatory pain [8]. Over time, the use of willow bark became more widespread. In 1763, Reverend [PERSON] conducted the first clinical research study on willow bark, confirming its antipyretic effects [7]. In 1827, salicylic acid, which was the active component of willow bark, was extracted and isolated by [PERSON] [9]. In 1853, [PERSON] manufactured acetylsalicylic acid [10]. In 1869, the structure of acetylsalicylic acid was accurately reported [11]. In 1897, salicin was successfully refined into aspirin [7; 12]. In 1987, the chemists of Bayer synthesized a steady acetylated salicate from salicylic acid. Salicylic acid was named aspirin by combining the two words acetyl and Spirsaure [13]. Aspirin could inhibit cyclooxygenase (COX), which inhibited prostaglandin synthesis and resulted in antipyretic, analgesic, and anti-inflammatory effects [14]. Even though salicin in willow bark served as a precursor to aspirin, its medical effect could not be solely attributed to it. Willow bark extract is commonly employed as a complementary therapy for pain and inflammation management, such as those related to low back pain, osteoarthritis, tendinitis, bursitis, and headaches. Nonetheless, the safety and effectiveness of willow bark extract are still being scrutinized [15]. There are several mechanisms to explain the adverse impact of arthritis on individuals. Osteoarthritis, the most prevalent arthritis, is characterized by the degeneration of cartilage. Cartilage degeneration can be triggered by excessive body weight, joint injuries, or advanced age. The characteristics of osteoarthritis are the remodeling of subchondral bone, the formation of ectopic bone and osteophytes, the hypertrophy of the joint capsule, and the inflammation of the synovial lining [16]. Of the individuals with osteoarthritis, 25% cannot perform major activities of daily living, and 80% suffer from some movement limitation [17]. With reduced physical activity caused by osteoarthritis, patients experience 20% higher age-adjusted mortality [18].